From 8ba2766b83aea8e21509ae02e8b55b81be7c5751 Mon Sep 17 00:00:00 2001
From: daikiumehara <daikiumehara3@gmail.com>
Date: Fri, 26 Apr 2024 19:43:33 +0900
Subject: [PATCH 01/24] edit: rename callbackFetchWeatherList to fetchWeather

---
 Sources/YumemiWeather/YumemiWeather.swift         | 4 ++--
 Sources/YumemiWeather/YumemiWeatherList.swift     | 4 ++--
 Tests/YumemiWeatherTests/YumemiWeatherTests.swift | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index e14c735..9dd8f33 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -183,7 +183,7 @@ final public class YumemiWeather {
     /// - Parameters:
     ///   - jsonString: 地域と日付を含む JSON 文字列
     ///   - completion: 完了コールバック
-    public static func callbackFetchWeather(_ jsonString: String, completion: @escaping (Result<String, YumemiWeatherError>) -> Void) {
+    public static func fetchWeather(_ jsonString: String, completion: @escaping (Result<String, YumemiWeatherError>) -> Void) {
         DispatchQueue.global().asyncAfter(deadline: .now() + apiDuration) {
             do {
                 let response = try fetchWeather(jsonString)
@@ -222,7 +222,7 @@ final public class YumemiWeather {
     @available(iOS 13, macOS 10.15, *)
     public static func asyncFetchWeather(_ jsonString: String) async throws -> String {
         return try await withCheckedThrowingContinuation { continuation in
-            callbackFetchWeather(jsonString) { result in
+            fetchWeather(jsonString) { result in
                 continuation.resume(with: result)
             }
         }
diff --git a/Sources/YumemiWeather/YumemiWeatherList.swift b/Sources/YumemiWeather/YumemiWeatherList.swift
index 0c7f87e..cd4b9a7 100644
--- a/Sources/YumemiWeather/YumemiWeatherList.swift
+++ b/Sources/YumemiWeather/YumemiWeatherList.swift
@@ -136,7 +136,7 @@ public extension YumemiWeather {
     /// - Parameters:
     ///   - jsonString: 地域と日付を含む JSON 文字列
     ///   - completion: 完了コールバック
-    static func callbackFetchWeatherList(_ jsonString: String, completion: @escaping (Result<String, YumemiWeatherError>) -> Void) {
+    static func fetchWeatherList(_ jsonString: String, completion: @escaping (Result<String, YumemiWeatherError>) -> Void) {
         DispatchQueue.global().asyncAfter(deadline: .now() + apiDuration) {
             do {
                 let response = try fetchWeatherList(jsonString)
@@ -178,7 +178,7 @@ public extension YumemiWeather {
     @available(iOS 13, macOS 10.15, *)
     static func asyncFetchWeatherList(_ jsonString: String) async throws -> String {
         return try await withCheckedThrowingContinuation { continuation in
-            callbackFetchWeatherList(jsonString) { result in
+            fetchWeatherList(jsonString) { result in
                 continuation.resume(with: result)
             }
         }
diff --git a/Tests/YumemiWeatherTests/YumemiWeatherTests.swift b/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
index 0392a4d..a826e77 100644
--- a/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
+++ b/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
@@ -80,7 +80,7 @@ final class YumemiWeatherTests: XCTestCase {
 }
 """
         let exp = expectation(description: #function)
-        YumemiWeather.callbackFetchWeather(parameter) { result in
+        YumemiWeather.fetchWeather(parameter) { result in
             exp.fulfill()
             switch result {
             case .success(let jsonString):

From 9520e85b9a53f9de92e048ba444400628252c1f2 Mon Sep 17 00:00:00 2001
From: daikiumehara <daikiumehara3@gmail.com>
Date: Fri, 26 Apr 2024 19:59:48 +0900
Subject: [PATCH 02/24] edit: remove unnecessary makeResponse code

---
 Sources/YumemiWeather/YumemiWeather.swift | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index 9dd8f33..e4529a5 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -55,12 +55,14 @@ final public class YumemiWeather {
     ///   - seed: シード値
     /// - Returns: Response構造体
 
-    static func makeRandomResponse(weatherCondition: WeatherCondition? = nil, maxTemperature: Int? = nil, minTemperature: Int? = nil, date: Date? = nil, seed: Int? = nil) -> Response {
-        return makeRandomResponse(weatherCondition: weatherCondition, maxTemperature: maxTemperature, minTemperature: minTemperature, date: date, seed: seed ?? Int.random(in: Int.min...Int.max))
-    }
-
-    private static func makeRandomResponse(weatherCondition: WeatherCondition?, maxTemperature: Int?, minTemperature: Int?, date: Date?, seed seedValue: Int) -> Response {
-        var generator = SeedRandomNumberGenerator(seed: seedValue)
+    static func makeRandomResponse(
+        weatherCondition: WeatherCondition? = nil,
+        maxTemperature: Int? = nil,
+        minTemperature: Int? = nil,
+        date: Date? = nil, 
+        seed: Int? = nil
+    ) -> Response {
+        var generator = SeedRandomNumberGenerator(seed: seed ?? Int.random(in: Int.min...Int.max))
         let weatherCondition = weatherCondition ?? WeatherCondition.allCases.randomElement(using: &generator)!
         let maxTemperature = maxTemperature ?? Int.random(in: 10...40, using: &generator)
         let minTemperature = minTemperature ?? Int.random(in: -40..<maxTemperature, using: &generator)

From d385448db1719883becea8097d85ca4a9084db7b Mon Sep 17 00:00:00 2001
From: daikiumehara <daikiumehara3@gmail.com>
Date: Tue, 30 Apr 2024 11:16:19 +0900
Subject: [PATCH 03/24] edit: refactor casting process

---
 Sources/YumemiWeather/YumemiWeather.swift     | 6 +++---
 Sources/YumemiWeather/YumemiWeatherList.swift | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index e4529a5..31a5a9a 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -189,10 +189,10 @@ final public class YumemiWeather {
         DispatchQueue.global().asyncAfter(deadline: .now() + apiDuration) {
             do {
                 let response = try fetchWeather(jsonString)
-                completion(Result.success(response))
+                completion(.success(response))
             }
-            catch let error where error is YumemiWeatherError {
-                completion(Result.failure(error as! YumemiWeatherError))
+            catch let error as YumemiWeatherError {
+                completion(.failure(error))
             }
             catch {
                 fatalError()
diff --git a/Sources/YumemiWeather/YumemiWeatherList.swift b/Sources/YumemiWeather/YumemiWeatherList.swift
index cd4b9a7..44ced8c 100644
--- a/Sources/YumemiWeather/YumemiWeatherList.swift
+++ b/Sources/YumemiWeather/YumemiWeatherList.swift
@@ -140,10 +140,10 @@ public extension YumemiWeather {
         DispatchQueue.global().asyncAfter(deadline: .now() + apiDuration) {
             do {
                 let response = try fetchWeatherList(jsonString)
-                completion(Result.success(response))
+                completion(.success(response))
             }
-            catch let error where error is YumemiWeatherError {
-                completion(Result.failure(error as! YumemiWeatherError))
+            catch let error as YumemiWeatherError {
+                completion(.failure(error))
             }
             catch {
                 fatalError()

From ebd0419d1675d17fcf3d4bb8ed824e66fd29070c Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Tue, 30 Apr 2024 23:12:05 +0900
Subject: [PATCH 04/24] =?UTF-8?q?Example=20=E3=81=AE=E3=83=86=E3=82=B9?=
 =?UTF-8?q?=E3=83=88=E3=82=B3=E3=83=BC=E3=83=89=E3=81=A7=20WeatherModel=20?=
 =?UTF-8?q?=E3=83=97=E3=83=AD=E3=83=88=E3=82=B3=E3=83=AB=E3=81=AE=E8=A6=81?=
 =?UTF-8?q?=E6=B1=82=E3=82=92=E6=BA=80=E3=81=9F=E3=81=9B=E3=81=A6=E3=81=84?=
 =?UTF-8?q?=E3=81=AA=E3=81=8B=E3=81=A3=E3=81=9F=E3=81=AE=E3=82=92=E4=BF=AE?=
 =?UTF-8?q?=E6=AD=A3=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../WeatherViewControllerTests.swift           | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/Example/ExampleTests/WeatherViewControllerTests.swift b/Example/ExampleTests/WeatherViewControllerTests.swift
index 402273d..498c9c5 100644
--- a/Example/ExampleTests/WeatherViewControllerTests.swift
+++ b/Example/ExampleTests/WeatherViewControllerTests.swift
@@ -28,7 +28,8 @@ class WeatherViewControllerTests: XCTestCase {
 
     func test_天気予報がsunnyだったらImageViewのImageにsunnyが設定されること_TintColorがredに設定されること() throws {
         weahterModel.fetchWeatherImpl = { _ in
-            Response(weather: .sunny, maxTemp: 0, minTemp: 0, date: Date())
+            let response = Response(weather: .sunny, maxTemp: 0, minTemp: 0, date: Date())
+            return Result.success(response)
         }
         
         weahterViewController.loadWeather()
@@ -38,7 +39,8 @@ class WeatherViewControllerTests: XCTestCase {
     
     func test_天気予報がcloudyだったらImageViewのImageにcloudyが設定されること_TintColorがgrayに設定されること() throws {
         weahterModel.fetchWeatherImpl = { _ in
-            Response(weather: .cloudy, maxTemp: 0, minTemp: 0, date: Date())
+            let response = Response(weather: .cloudy, maxTemp: 0, minTemp: 0, date: Date())
+            return Result.success(response)
         }
         
         weahterViewController.loadWeather()
@@ -48,7 +50,8 @@ class WeatherViewControllerTests: XCTestCase {
     
     func test_天気予報がrainyだったらImageViewのImageにrainyが設定されること_TintColorがblueに設定されること() throws {
         weahterModel.fetchWeatherImpl = { _ in
-            Response(weather: .rainy, maxTemp: 0, minTemp: 0, date: Date())
+            let response = Response(weather: .rainy, maxTemp: 0, minTemp: 0, date: Date())
+            return Result.success(response)
         }
         
         weahterViewController.loadWeather()
@@ -58,7 +61,8 @@ class WeatherViewControllerTests: XCTestCase {
     
     func test_最高気温_最低気温がUILabelに設定されること() throws {
         weahterModel.fetchWeatherImpl = { _ in
-            Response(weather: .rainy, maxTemp: 100, minTemp: -100, date: Date())
+            let response = Response(weather: .rainy, maxTemp: 100, minTemp: -100, date: Date())
+            return Result.success(response)
         }
         
         weahterViewController.loadWeather()
@@ -69,9 +73,9 @@ class WeatherViewControllerTests: XCTestCase {
 
 class WeatherModelMock: WeatherModel {
     
-    var fetchWeatherImpl: ((Request) throws -> Response)!
+    var fetchWeatherImpl: ((Request) -> Result<Response, WeatherError>)!
     
-    func fetchWeather(_ request: Request) throws -> Response {
-        return try fetchWeatherImpl(request)
+    func fetchWeather(at area: String, date: Date, completion: @escaping (Result<Response, WeatherError>) -> Void) {
+        completion(fetchWeatherImpl(Request(area: area, date: date)))
     }
 }

From 50276c9dbb0d4f2260bbf5bb7d2386babec5ab6d Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Tue, 30 Apr 2024 23:23:07 +0900
Subject: [PATCH 05/24] =?UTF-8?q?Example=20=E3=83=86=E3=82=B9=E3=83=88?=
 =?UTF-8?q?=E3=82=B3=E3=83=BC=E3=83=89=E5=86=85=E3=81=A7=E3=80=81loadWeath?=
 =?UTF-8?q?er=20=E3=83=A1=E3=82=BD=E3=83=83=E3=83=89=E3=81=AB=E3=81=9D?=
 =?UTF-8?q?=E3=81=AE=E5=91=BC=E3=81=B3=E5=87=BA=E3=81=97=E4=B8=BB=E3=81=8C?=
 =?UTF-8?q?=E6=B8=A1=E3=81=95=E3=82=8C=E3=81=A6=E3=81=84=E3=81=AA=E3=81=84?=
 =?UTF-8?q?=E3=81=AE=E3=82=92=E4=BF=AE=E6=AD=A3=E3=81=97=E3=81=BE=E3=81=97?=
 =?UTF-8?q?=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Example/ExampleTests/WeatherViewControllerTests.swift | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Example/ExampleTests/WeatherViewControllerTests.swift b/Example/ExampleTests/WeatherViewControllerTests.swift
index 498c9c5..ba737ca 100644
--- a/Example/ExampleTests/WeatherViewControllerTests.swift
+++ b/Example/ExampleTests/WeatherViewControllerTests.swift
@@ -32,7 +32,7 @@ class WeatherViewControllerTests: XCTestCase {
             return Result.success(response)
         }
         
-        weahterViewController.loadWeather()
+        weahterViewController.loadWeather(self)
         XCTAssertEqual(weahterViewController.weatherImageView.tintColor, R.color.red())
         XCTAssertEqual(weahterViewController.weatherImageView.image, R.image.sunny())
     }
@@ -43,7 +43,7 @@ class WeatherViewControllerTests: XCTestCase {
             return Result.success(response)
         }
         
-        weahterViewController.loadWeather()
+        weahterViewController.loadWeather(self)
         XCTAssertEqual(weahterViewController.weatherImageView.tintColor, R.color.gray())
         XCTAssertEqual(weahterViewController.weatherImageView.image, R.image.cloudy())
     }
@@ -54,7 +54,7 @@ class WeatherViewControllerTests: XCTestCase {
             return Result.success(response)
         }
         
-        weahterViewController.loadWeather()
+        weahterViewController.loadWeather(self)
         XCTAssertEqual(weahterViewController.weatherImageView.tintColor, R.color.blue())
         XCTAssertEqual(weahterViewController.weatherImageView.image, R.image.rainy())
     }
@@ -65,7 +65,7 @@ class WeatherViewControllerTests: XCTestCase {
             return Result.success(response)
         }
         
-        weahterViewController.loadWeather()
+        weahterViewController.loadWeather(self)
         XCTAssertEqual(weahterViewController.minTempLabel.text, "-100")
         XCTAssertEqual(weahterViewController.maxTempLabel.text, "100")
     }

From 70f228f8c246e2e2c071aacc9e156f9243de690b Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Tue, 30 Apr 2024 23:38:05 +0900
Subject: [PATCH 06/24] =?UTF-8?q?WeatherViewController=20=E3=81=AB=20Disas?=
 =?UTF-8?q?terModelMock=20=E3=81=8C=E8=A8=AD=E5=AE=9A=E3=81=95=E3=82=8C?=
 =?UTF-8?q?=E3=81=A6=E3=81=84=E3=81=AA=E3=81=84=E3=81=93=E3=81=A8=E3=81=8C?=
 =?UTF-8?q?=E5=8E=9F=E5=9B=A0=E3=81=A7=E3=80=81=E3=83=86=E3=82=B9=E3=83=88?=
 =?UTF-8?q?=E3=81=8C=E5=BC=B7=E5=88=B6=E7=B5=82=E4=BA=86=E3=81=99=E3=82=8B?=
 =?UTF-8?q?=E3=81=AE=E3=82=92=E4=BF=AE=E6=AD=A3=E3=81=97=E3=81=BE=E3=81=97?=
 =?UTF-8?q?=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Example/ExampleTests/WeatherViewControllerTests.swift | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Example/ExampleTests/WeatherViewControllerTests.swift b/Example/ExampleTests/WeatherViewControllerTests.swift
index ba737ca..1839910 100644
--- a/Example/ExampleTests/WeatherViewControllerTests.swift
+++ b/Example/ExampleTests/WeatherViewControllerTests.swift
@@ -19,6 +19,8 @@ class WeatherViewControllerTests: XCTestCase {
         weahterModel = WeatherModelMock()
         weahterViewController = R.storyboard.weather.instantiateInitialViewController()!
         weahterViewController.weatherModel = weahterModel
+        weahterViewController.disasterModel = DisasterModelMock()
+        
         _ = weahterViewController.view
     }
 
@@ -79,3 +81,10 @@ class WeatherModelMock: WeatherModel {
         completion(fetchWeatherImpl(Request(area: area, date: date)))
     }
 }
+
+final class DisasterModelMock: DisasterModel {
+
+    func fetchDisaster(completion: ((String) -> Void)?) {
+        completion?("只今、災害情報はありません。")
+    }
+}

From 2d2da356e78adf5a0a18de5d246f991faa20d08f Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Wed, 1 May 2024 00:01:37 +0900
Subject: [PATCH 07/24] =?UTF-8?q?WeatherImageView=20=E3=81=B8=E3=81=AE?=
 =?UTF-8?q?=E5=8F=8D=E6=98=A0=E3=82=92=E5=BE=85=E3=81=9F=E3=81=9A=E3=81=AB?=
 =?UTF-8?q?=20XCTAssertEqual=20=E3=81=A7=E7=B5=90=E6=9E=9C=E5=88=A4?=
 =?UTF-8?q?=E5=AE=9A=E3=82=92=E3=81=97=E3=81=A6=E5=A4=B1=E6=95=97=E3=81=97?=
 =?UTF-8?q?=E3=81=A6=E3=81=84=E3=81=9F=E7=AE=87=E6=89=80=E3=82=92=E4=BF=AE?=
 =?UTF-8?q?=E6=AD=A3=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

現状の WeatherViewController には反映完了を検出する術がなさそうだったため、やや強引かつ不確実なテストコードになりました。
---
 .../WeatherViewControllerTests.swift          | 20 +++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/Example/ExampleTests/WeatherViewControllerTests.swift b/Example/ExampleTests/WeatherViewControllerTests.swift
index 1839910..15ee7a3 100644
--- a/Example/ExampleTests/WeatherViewControllerTests.swift
+++ b/Example/ExampleTests/WeatherViewControllerTests.swift
@@ -28,46 +28,58 @@ class WeatherViewControllerTests: XCTestCase {
         // Put teardown code here. This method is called after the invocation of each test method in the class.
     }
 
-    func test_天気予報がsunnyだったらImageViewのImageにsunnyが設定されること_TintColorがredに設定されること() throws {
+    @MainActor
+    func test_天気予報がsunnyだったらImageViewのImageにsunnyが設定されること_TintColorがredに設定されること() async throws {
         weahterModel.fetchWeatherImpl = { _ in
             let response = Response(weather: .sunny, maxTemp: 0, minTemp: 0, date: Date())
             return Result.success(response)
         }
         
         weahterViewController.loadWeather(self)
+        await Task.yield()
+
         XCTAssertEqual(weahterViewController.weatherImageView.tintColor, R.color.red())
         XCTAssertEqual(weahterViewController.weatherImageView.image, R.image.sunny())
     }
     
-    func test_天気予報がcloudyだったらImageViewのImageにcloudyが設定されること_TintColorがgrayに設定されること() throws {
+    @MainActor
+    func test_天気予報がcloudyだったらImageViewのImageにcloudyが設定されること_TintColorがgrayに設定されること() async throws {
         weahterModel.fetchWeatherImpl = { _ in
             let response = Response(weather: .cloudy, maxTemp: 0, minTemp: 0, date: Date())
             return Result.success(response)
         }
         
         weahterViewController.loadWeather(self)
+        await Task.yield()
+        
         XCTAssertEqual(weahterViewController.weatherImageView.tintColor, R.color.gray())
         XCTAssertEqual(weahterViewController.weatherImageView.image, R.image.cloudy())
     }
     
-    func test_天気予報がrainyだったらImageViewのImageにrainyが設定されること_TintColorがblueに設定されること() throws {
+    @MainActor
+    func test_天気予報がrainyだったらImageViewのImageにrainyが設定されること_TintColorがblueに設定されること() async throws {
         weahterModel.fetchWeatherImpl = { _ in
             let response = Response(weather: .rainy, maxTemp: 0, minTemp: 0, date: Date())
             return Result.success(response)
         }
         
         weahterViewController.loadWeather(self)
+        await Task.yield()
+        
         XCTAssertEqual(weahterViewController.weatherImageView.tintColor, R.color.blue())
         XCTAssertEqual(weahterViewController.weatherImageView.image, R.image.rainy())
     }
     
-    func test_最高気温_最低気温がUILabelに設定されること() throws {
+    @MainActor
+    func test_最高気温_最低気温がUILabelに設定されること() async throws {
         weahterModel.fetchWeatherImpl = { _ in
             let response = Response(weather: .rainy, maxTemp: 100, minTemp: -100, date: Date())
             return Result.success(response)
         }
         
         weahterViewController.loadWeather(self)
+        await Task.yield()
+        
         XCTAssertEqual(weahterViewController.minTempLabel.text, "-100")
         XCTAssertEqual(weahterViewController.maxTempLabel.text, "100")
     }

From f8d13aee5cc6eda642324deb89ae2229e35d0d74 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Wed, 1 May 2024 00:06:28 +0900
Subject: [PATCH 08/24] =?UTF-8?q?=E3=83=86=E3=82=B9=E3=83=88=E3=82=B3?=
 =?UTF-8?q?=E3=83=BC=E3=83=89=E5=86=85=E3=81=AE=20typo=20=E3=82=92?=
 =?UTF-8?q?=E4=BF=AE=E6=AD=A3=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../WeatherViewControllerTests.swift          | 46 +++++++++----------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/Example/ExampleTests/WeatherViewControllerTests.swift b/Example/ExampleTests/WeatherViewControllerTests.swift
index 15ee7a3..fe40aa3 100644
--- a/Example/ExampleTests/WeatherViewControllerTests.swift
+++ b/Example/ExampleTests/WeatherViewControllerTests.swift
@@ -12,16 +12,16 @@ import YumemiWeather
 
 class WeatherViewControllerTests: XCTestCase {
 
-    var weahterViewController: WeatherViewController!
-    var weahterModel: WeatherModelMock!
+    var weatherViewController: WeatherViewController!
+    var weatherModel: WeatherModelMock!
     
     override func setUpWithError() throws {
-        weahterModel = WeatherModelMock()
-        weahterViewController = R.storyboard.weather.instantiateInitialViewController()!
-        weahterViewController.weatherModel = weahterModel
-        weahterViewController.disasterModel = DisasterModelMock()
+        weatherModel = WeatherModelMock()
+        weatherViewController = R.storyboard.weather.instantiateInitialViewController()!
+        weatherViewController.weatherModel = weatherModel
+        weatherViewController.disasterModel = DisasterModelMock()
         
-        _ = weahterViewController.view
+        _ = weatherViewController.view
     }
 
     override func tearDownWithError() throws {
@@ -30,58 +30,58 @@ class WeatherViewControllerTests: XCTestCase {
 
     @MainActor
     func test_天気予報がsunnyだったらImageViewのImageにsunnyが設定されること_TintColorがredに設定されること() async throws {
-        weahterModel.fetchWeatherImpl = { _ in
+        weatherModel.fetchWeatherImpl = { _ in
             let response = Response(weather: .sunny, maxTemp: 0, minTemp: 0, date: Date())
             return Result.success(response)
         }
         
-        weahterViewController.loadWeather(self)
+        weatherViewController.loadWeather(self)
         await Task.yield()
 
-        XCTAssertEqual(weahterViewController.weatherImageView.tintColor, R.color.red())
-        XCTAssertEqual(weahterViewController.weatherImageView.image, R.image.sunny())
+        XCTAssertEqual(weatherViewController.weatherImageView.tintColor, R.color.red())
+        XCTAssertEqual(weatherViewController.weatherImageView.image, R.image.sunny())
     }
     
     @MainActor
     func test_天気予報がcloudyだったらImageViewのImageにcloudyが設定されること_TintColorがgrayに設定されること() async throws {
-        weahterModel.fetchWeatherImpl = { _ in
+        weatherModel.fetchWeatherImpl = { _ in
             let response = Response(weather: .cloudy, maxTemp: 0, minTemp: 0, date: Date())
             return Result.success(response)
         }
         
-        weahterViewController.loadWeather(self)
+        weatherViewController.loadWeather(self)
         await Task.yield()
         
-        XCTAssertEqual(weahterViewController.weatherImageView.tintColor, R.color.gray())
-        XCTAssertEqual(weahterViewController.weatherImageView.image, R.image.cloudy())
+        XCTAssertEqual(weatherViewController.weatherImageView.tintColor, R.color.gray())
+        XCTAssertEqual(weatherViewController.weatherImageView.image, R.image.cloudy())
     }
     
     @MainActor
     func test_天気予報がrainyだったらImageViewのImageにrainyが設定されること_TintColorがblueに設定されること() async throws {
-        weahterModel.fetchWeatherImpl = { _ in
+        weatherModel.fetchWeatherImpl = { _ in
             let response = Response(weather: .rainy, maxTemp: 0, minTemp: 0, date: Date())
             return Result.success(response)
         }
         
-        weahterViewController.loadWeather(self)
+        weatherViewController.loadWeather(self)
         await Task.yield()
         
-        XCTAssertEqual(weahterViewController.weatherImageView.tintColor, R.color.blue())
-        XCTAssertEqual(weahterViewController.weatherImageView.image, R.image.rainy())
+        XCTAssertEqual(weatherViewController.weatherImageView.tintColor, R.color.blue())
+        XCTAssertEqual(weatherViewController.weatherImageView.image, R.image.rainy())
     }
     
     @MainActor
     func test_最高気温_最低気温がUILabelに設定されること() async throws {
-        weahterModel.fetchWeatherImpl = { _ in
+        weatherModel.fetchWeatherImpl = { _ in
             let response = Response(weather: .rainy, maxTemp: 100, minTemp: -100, date: Date())
             return Result.success(response)
         }
         
-        weahterViewController.loadWeather(self)
+        weatherViewController.loadWeather(self)
         await Task.yield()
         
-        XCTAssertEqual(weahterViewController.minTempLabel.text, "-100")
-        XCTAssertEqual(weahterViewController.maxTempLabel.text, "100")
+        XCTAssertEqual(weatherViewController.minTempLabel.text, "-100")
+        XCTAssertEqual(weatherViewController.maxTempLabel.text, "100")
     }
 }
 

From 81f35eb4d3682bb56c2541f97f883878aa6bf8b9 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Wed, 1 May 2024 00:08:27 +0900
Subject: [PATCH 09/24] =?UTF-8?q?=E3=83=86=E3=82=B9=E3=83=88=E3=82=B3?=
 =?UTF-8?q?=E3=83=BC=E3=83=89=E3=81=A7=E3=81=AE=20View=20=E3=81=AE?=
 =?UTF-8?q?=E6=BA=96=E5=82=99=E3=81=AF=E3=80=81=E3=83=93=E3=83=A5=E3=83=BC?=
 =?UTF-8?q?=E3=81=B8=E3=81=AE=E3=83=97=E3=83=AD=E3=83=91=E3=83=86=E3=82=A3?=
 =?UTF-8?q?=E3=83=BC=E3=82=A2=E3=82=AF=E3=82=BB=E3=82=B9=E3=82=92=E6=8D=A8?=
 =?UTF-8?q?=E3=81=A6=E3=82=8B=E6=96=B9=E6=B3=95=E3=81=A7=E3=81=AF=E3=81=AA?=
 =?UTF-8?q?=E3=81=8F=20'loadViewIfNeeded`=20=E3=82=92=E5=91=BC=E3=81=B3?=
 =?UTF-8?q?=E5=87=BA=E3=81=99=E6=96=B9=E6=B3=95=E3=81=AB=E3=81=97=E3=81=BE?=
 =?UTF-8?q?=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Example/ExampleTests/WeatherViewControllerTests.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Example/ExampleTests/WeatherViewControllerTests.swift b/Example/ExampleTests/WeatherViewControllerTests.swift
index fe40aa3..29631bf 100644
--- a/Example/ExampleTests/WeatherViewControllerTests.swift
+++ b/Example/ExampleTests/WeatherViewControllerTests.swift
@@ -21,7 +21,7 @@ class WeatherViewControllerTests: XCTestCase {
         weatherViewController.weatherModel = weatherModel
         weatherViewController.disasterModel = DisasterModelMock()
         
-        _ = weatherViewController.view
+        weatherViewController.loadViewIfNeeded()
     }
 
     override func tearDownWithError() throws {

From c1fb6be5ab665113fd940afe708b7d0161484d91 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Wed, 1 May 2024 00:10:51 +0900
Subject: [PATCH 10/24] =?UTF-8?q?=E5=B0=91=E3=81=AA=E3=81=8F=E3=81=A8?=
 =?UTF-8?q?=E3=82=82=E7=8F=BE=E7=8A=B6=E3=81=AE=E3=83=86=E3=82=B9=E3=83=88?=
 =?UTF-8?q?=E3=82=B3=E3=83=BC=E3=83=89=E3=81=A7=E3=81=AF=20WeatherModelMoc?=
 =?UTF-8?q?k=20=E3=82=92=20'setUpWithError'=20=E3=81=BE=E3=81=A7=E5=BE=85?=
 =?UTF-8?q?=E3=81=9F=E3=81=AA=E3=81=8F=E3=81=A6=E3=82=82=E6=BA=96=E5=82=99?=
 =?UTF-8?q?=E3=81=A7=E3=81=8D=E3=82=8B=E3=81=9F=E3=82=81=E3=80=81=E4=B8=8D?=
 =?UTF-8?q?=E5=BF=85=E8=A6=81=E3=81=AB=20IUO=20=E3=82=AA=E3=83=97=E3=82=B7?=
 =?UTF-8?q?=E3=83=A7=E3=83=8A=E3=83=AB=E3=82=92=E4=BD=BF=E3=82=8F=E3=81=AA?=
 =?UTF-8?q?=E3=81=84=E3=82=88=E3=81=86=E3=81=AB=E3=81=97=E3=81=BE=E3=81=97?=
 =?UTF-8?q?=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Example/ExampleTests/WeatherViewControllerTests.swift | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Example/ExampleTests/WeatherViewControllerTests.swift b/Example/ExampleTests/WeatherViewControllerTests.swift
index 29631bf..5d9018c 100644
--- a/Example/ExampleTests/WeatherViewControllerTests.swift
+++ b/Example/ExampleTests/WeatherViewControllerTests.swift
@@ -13,10 +13,9 @@ import YumemiWeather
 class WeatherViewControllerTests: XCTestCase {
 
     var weatherViewController: WeatherViewController!
-    var weatherModel: WeatherModelMock!
+    var weatherModel = WeatherModelMock()
     
     override func setUpWithError() throws {
-        weatherModel = WeatherModelMock()
         weatherViewController = R.storyboard.weather.instantiateInitialViewController()!
         weatherViewController.weatherModel = weatherModel
         weatherViewController.disasterModel = DisasterModelMock()

From acb3ddaf861d8350be2157f634a75fa2bfa69342 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Wed, 1 May 2024 00:56:04 +0900
Subject: [PATCH 11/24] =?UTF-8?q?=E5=8D=98=E7=8B=AC=E3=81=A7=E5=AD=98?=
 =?UTF-8?q?=E5=9C=A8=E3=81=97=E3=81=A6=E3=81=84=E3=81=9F=E3=80=81=E4=B8=8D?=
 =?UTF-8?q?=E5=BF=85=E8=A6=81=E3=81=AA=E3=83=89=E3=82=AD=E3=83=A5=E3=83=A1?=
 =?UTF-8?q?=E3=83=B3=E3=83=88=E3=82=B3=E3=83=A1=E3=83=B3=E3=83=88=E3=82=92?=
 =?UTF-8?q?=E5=89=8A=E9=99=A4=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Sources/YumemiWeather/YumemiWeather.swift | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index 31a5a9a..eec01b4 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -157,11 +157,6 @@ final public class YumemiWeather {
         Thread.sleep(forTimeInterval: apiDuration)
         return try self.fetchWeather(jsonString)
     }
-
-
-    /// - Throws: YumemiWeatherError パラメータが正常でもランダムにエラーが発生する
-    /// - Parameter jsonString: 地域と日付を含む JSON 文字列
-    /// - Returns: Weather レスポンスの JSON 文字列
     
     /// 擬似 天気予報 API Callback ver
     ///

From ee6cf6d35120fe58107ac2174d9ef730ca3c51ca Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Wed, 1 May 2024 02:19:54 +0900
Subject: [PATCH 12/24] =?UTF-8?q?self.=20=E3=81=AF=E7=9C=81=E7=95=A5?=
 =?UTF-8?q?=E3=81=95=E3=82=8C=E3=82=8B=E5=82=BE=E5=90=91=E3=81=8C=E3=81=82?=
 =?UTF-8?q?=E3=82=8B=E3=81=9F=E3=82=81=E3=80=81=E3=81=9D=E3=82=8C=E3=81=8C?=
 =?UTF-8?q?=E6=98=8E=E3=82=89=E3=81=8B=E3=81=AB=E4=B8=8D=E8=A6=81=E3=81=AA?=
 =?UTF-8?q?=E7=AE=87=E6=89=80=E3=81=AB=E3=81=A4=E3=81=84=E3=81=A6=E3=81=AF?=
 =?UTF-8?q?=E7=9C=81=E7=95=A5=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

省略推奨についての確かな根拠は見つけられませんでした。以前に The Swift Programming Language で「通常は省略する」という記載があった気がしたのですけれど、探しても見つけられなかったため、省略しない方針もアリかもしれません。その場合はこのコミットを Revert しましょう。
---
 Example/Example/Model/DisasterModel.swift     |  6 ++---
 .../UI/Weather/WeatherViewController.swift    | 26 +++++++++----------
 Sources/YumemiWeather/YumemiDisaster.swift    |  2 +-
 Sources/YumemiWeather/YumemiWeather.swift     |  6 ++---
 Sources/YumemiWeather/YumemiWeatherList.swift |  2 +-
 .../YumemiWeatherTests.swift                  |  2 +-
 6 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/Example/Example/Model/DisasterModel.swift b/Example/Example/Model/DisasterModel.swift
index 8dc5e03..eb1c190 100644
--- a/Example/Example/Model/DisasterModel.swift
+++ b/Example/Example/Model/DisasterModel.swift
@@ -20,15 +20,15 @@ class DisasterModelImpl: DisasterModel {
     }
 
     func fetchDisaster(completion: ((String) -> Void)?) {
-        self.fetchDisasterHandler = completion
-        self.yumemiDisaster.fetchDisaster()
+        fetchDisasterHandler = completion
+        yumemiDisaster.fetchDisaster()
     }
 }
 
 extension DisasterModelImpl: YumemiDisasterHandleDelegate {
     
     func handle(disaster: String) {
-        self.fetchDisasterHandler?(disaster)
+        fetchDisasterHandler?(disaster)
     }
     
 }
diff --git a/Example/Example/UI/Weather/WeatherViewController.swift b/Example/Example/UI/Weather/WeatherViewController.swift
index 0bde51d..68c8822 100644
--- a/Example/Example/UI/Weather/WeatherViewController.swift
+++ b/Example/Example/UI/Weather/WeatherViewController.swift
@@ -30,7 +30,7 @@ class WeatherViewController: UIViewController {
         super.viewDidLoad()
         
         NotificationCenter.default.addObserver(forName: UIApplication.didBecomeActiveNotification, object: nil, queue: nil) { [unowned self] notification in
-            self.loadWeather(notification.object)
+            loadWeather(notification.object)
         }
     }
     
@@ -39,11 +39,11 @@ class WeatherViewController: UIViewController {
     }
             
     @IBAction func dismiss(_ sender: Any) {
-        self.dismiss(animated: true, completion: nil)
+        dismiss(animated: true, completion: nil)
     }
     
     @IBAction func loadWeather(_ sender: Any?) {
-        self.activityIndicator.startAnimating()
+        activityIndicator.startAnimating()
         weatherModel.fetchWeather(at: "tokyo", date: Date()) { result in
             DispatchQueue.main.async {
                 self.activityIndicator.stopAnimating()
@@ -58,9 +58,9 @@ class WeatherViewController: UIViewController {
     func handleWeather(result: Result<Response, WeatherError>) {
         switch result {
         case .success(let response):
-            self.weatherImageView.set(weather: response.weather)
-            self.minTempLabel.text = String(response.minTemp)
-            self.maxTempLabel.text = String(response.maxTemp)
+            weatherImageView.set(weather: response.weather)
+            minTempLabel.text = String(response.minTemp)
+            maxTempLabel.text = String(response.maxTemp)
             
         case .failure(let error):
             let message: String
@@ -79,7 +79,7 @@ class WeatherViewController: UIViewController {
                     print("Close ViewController by \(alertController)")
                 }
             })
-            self.present(alertController, animated: true, completion: nil)
+            present(alertController, animated: true, completion: nil)
         }
     }
 }
@@ -88,14 +88,14 @@ private extension UIImageView {
     func set(weather: Weather) {
         switch weather {
         case .sunny:
-            self.image = R.image.sunny()
-            self.tintColor = R.color.red()
+            image = R.image.sunny()
+            tintColor = R.color.red()
         case .cloudy:
-            self.image = R.image.cloudy()
-            self.tintColor = R.color.gray()
+            image = R.image.cloudy()
+            tintColor = R.color.gray()
         case .rainy:
-            self.image = R.image.rainy()
-            self.tintColor = R.color.blue()
+            image = R.image.rainy()
+            tintColor = R.color.blue()
         }
     }
 }
diff --git a/Sources/YumemiWeather/YumemiDisaster.swift b/Sources/YumemiWeather/YumemiDisaster.swift
index 7af4390..84fdbc0 100644
--- a/Sources/YumemiWeather/YumemiDisaster.swift
+++ b/Sources/YumemiWeather/YumemiDisaster.swift
@@ -18,7 +18,7 @@ public class YumemiDisaster {
     public init() {}
     
     public func fetchDisaster() {
-        self.delegate?.handle(disaster: "只今、災害情報はありません。")
+        delegate?.handle(disaster: "只今、災害情報はありません。")
     }
     
 }
diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index eec01b4..3c95dc3 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -79,7 +79,7 @@ final public class YumemiWeather {
     /// 擬似 天気予報 API Simple ver
     /// - Returns: 天気状況を表す文字列 "sunny" or "cloudy" or "rainy"
     public static func fetchWeatherCondition() -> String {
-        return self.makeRandomResponse().weatherCondition
+        return makeRandomResponse().weatherCondition
     }
 
     /// 擬似 天気予報 API Throws ver
@@ -92,7 +92,7 @@ final public class YumemiWeather {
             throw YumemiWeatherError.unknownError
         }
 
-        return self.makeRandomResponse().weatherCondition
+        return makeRandomResponse().weatherCondition
     }
 
     /// 擬似 天気予報 API JSON ver
@@ -155,7 +155,7 @@ final public class YumemiWeather {
     /// - Returns: Weather レスポンスの JSON 文字列
     public static func syncFetchWeather(_ jsonString: String) throws -> String {
         Thread.sleep(forTimeInterval: apiDuration)
-        return try self.fetchWeather(jsonString)
+        return try fetchWeather(jsonString)
     }
     
     /// 擬似 天気予報 API Callback ver
diff --git a/Sources/YumemiWeather/YumemiWeatherList.swift b/Sources/YumemiWeather/YumemiWeatherList.swift
index 44ced8c..9ff9902 100644
--- a/Sources/YumemiWeather/YumemiWeatherList.swift
+++ b/Sources/YumemiWeather/YumemiWeatherList.swift
@@ -106,7 +106,7 @@ public extension YumemiWeather {
     /// - Returns: 返された AreaResponse の JSON 文字列
     static func syncFetchWeatherList(_ jsonString: String) throws -> String {
         Thread.sleep(forTimeInterval: apiDuration)
-        return try self.fetchWeatherList(jsonString)
+        return try fetchWeatherList(jsonString)
     }
 
     /// 擬似 天気予報一覧 API Callback ver
diff --git a/Tests/YumemiWeatherTests/YumemiWeatherTests.swift b/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
index a826e77..322a95c 100644
--- a/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
+++ b/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
@@ -94,7 +94,7 @@ final class YumemiWeatherTests: XCTestCase {
                 XCTAssertEqual(error, YumemiWeatherError.unknownError)
             }
         }
-        self.wait(for: [exp], timeout: YumemiWeather.apiDuration + 0.1)
+        wait(for: [exp], timeout: YumemiWeather.apiDuration + 0.1)
     }
 
     @available(iOS 13, macOS 10.15, *)

From 17daa5f479753064eae3737dd9cd9d20c1279b6b Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Wed, 1 May 2024 21:54:38 +0900
Subject: [PATCH 13/24] =?UTF-8?q?ThreadBlock=20=E3=81=AE=E8=AA=B2=E9=A1=8C?=
 =?UTF-8?q?=E6=96=87=E3=81=AB=E3=80=81=E4=BD=BF=E7=94=A8=E3=81=99=E3=82=8B?=
 =?UTF-8?q?=20API=20=E3=81=AE=E7=89=B9=E5=BE=B4=E8=AA=AC=E6=98=8E=E3=82=92?=
 =?UTF-8?q?=E8=BF=BD=E8=A8=98=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Documentation/ThreadBlock.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/ThreadBlock.md b/Documentation/ThreadBlock.md
index 7997067..f05909f 100644
--- a/Documentation/ThreadBlock.md
+++ b/Documentation/ThreadBlock.md
@@ -6,6 +6,9 @@ Sync ver
 ```swift
 static func syncFetchWeather(_ jsonString: String) throws -> String
 ```
+
+このメソッドは、値を返すまでに少し時間がかかります。
+
 [APIの概要](YumemiWeather.md)  
 
 ## 課題

From b7bf09c2ca7c43546ee5a7374e55be2b54b7c7b3 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Wed, 1 May 2024 21:57:18 +0900
Subject: [PATCH 14/24] =?UTF-8?q?YumemiWeather=20=E3=82=AF=E3=83=A9?=
 =?UTF-8?q?=E3=82=B9=E3=81=AE=E8=A6=8B=E9=80=9A=E3=81=97=E3=82=92=E8=89=AF?=
 =?UTF-8?q?=E3=81=8F=E3=81=99=E3=82=8B=E3=81=9F=E3=82=81=E3=81=AB=E3=80=81?=
 =?UTF-8?q?=E5=A4=96=E9=83=A8=E5=85=AC=E9=96=8B=E3=81=99=E3=82=8B=20API=20?=
 =?UTF-8?q?=E3=81=AE=E6=A9=9F=E8=83=BD=E3=81=A8=E3=81=9D=E3=82=8C=E4=BB=A5?=
 =?UTF-8?q?=E5=A4=96=E3=81=A8=E3=82=92=E5=8C=BA=E5=88=A5=E3=81=97=E3=81=A6?=
 =?UTF-8?q?=E5=AE=9A=E7=BE=A9=E3=81=99=E3=82=8B=E3=82=88=E3=81=86=E3=81=AB?=
 =?UTF-8?q?=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Sources/YumemiWeather/YumemiWeather.swift | 105 +++++++++++-----------
 1 file changed, 54 insertions(+), 51 deletions(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index 3c95dc3..18b97d1 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -25,57 +25,6 @@ public enum YumemiWeatherError: Swift.Error {
 
 final public class YumemiWeather {
 
-    static let apiDuration: TimeInterval = 2
-
-    private static let dateFormatter: DateFormatter = {
-        let dateFormatter = DateFormatter()
-        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
-        return dateFormatter
-    }()
-
-    static let decoder: JSONDecoder = {
-        let decoder = JSONDecoder()
-        decoder.dateDecodingStrategy = .formatted(dateFormatter)
-        return decoder
-    }()
-
-    static let encoder: JSONEncoder = {
-        let encoder = JSONEncoder()
-        encoder.keyEncodingStrategy = .convertToSnakeCase
-        encoder.dateEncodingStrategy = .formatted(dateFormatter)
-        return encoder
-    }()
-
-    /// 引数の値でResponse構造体を作成する。引数がnilの場合はランダムに値を作成する。
-    /// - Parameters:
-    ///   - weatherCondition: 天気状況を表すenum
-    ///   - maxTemperature: 最高気温
-    ///   - minTemperature: 最低気温
-    ///   - date: 日付
-    ///   - seed: シード値
-    /// - Returns: Response構造体
-
-    static func makeRandomResponse(
-        weatherCondition: WeatherCondition? = nil,
-        maxTemperature: Int? = nil,
-        minTemperature: Int? = nil,
-        date: Date? = nil, 
-        seed: Int? = nil
-    ) -> Response {
-        var generator = SeedRandomNumberGenerator(seed: seed ?? Int.random(in: Int.min...Int.max))
-        let weatherCondition = weatherCondition ?? WeatherCondition.allCases.randomElement(using: &generator)!
-        let maxTemperature = maxTemperature ?? Int.random(in: 10...40, using: &generator)
-        let minTemperature = minTemperature ?? Int.random(in: -40..<maxTemperature, using: &generator)
-        let date = date ?? Date()
-
-        return Response(
-            weatherCondition: weatherCondition.rawValue,
-            maxTemperature: maxTemperature,
-            minTemperature: minTemperature,
-            date: date
-        )
-    }
-
     /// 擬似 天気予報 API Simple ver
     /// - Returns: 天気状況を表す文字列 "sunny" or "cloudy" or "rainy"
     public static func fetchWeatherCondition() -> String {
@@ -225,3 +174,57 @@ final public class YumemiWeather {
         }
     }
 }
+
+extension YumemiWeather {
+    
+    static let apiDuration: TimeInterval = 2
+
+    private static let dateFormatter: DateFormatter = {
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
+        return dateFormatter
+    }()
+
+    static let decoder: JSONDecoder = {
+        let decoder = JSONDecoder()
+        decoder.dateDecodingStrategy = .formatted(dateFormatter)
+        return decoder
+    }()
+
+    static let encoder: JSONEncoder = {
+        let encoder = JSONEncoder()
+        encoder.keyEncodingStrategy = .convertToSnakeCase
+        encoder.dateEncodingStrategy = .formatted(dateFormatter)
+        return encoder
+    }()
+    
+    /// 引数の値でResponse構造体を作成する。引数がnilの場合はランダムに値を作成する。
+    /// - Parameters:
+    ///   - weatherCondition: 天気状況を表すenum
+    ///   - maxTemperature: 最高気温
+    ///   - minTemperature: 最低気温
+    ///   - date: 日付
+    ///   - seed: シード値
+    /// - Returns: Response構造体
+
+    static func makeRandomResponse(
+        weatherCondition: WeatherCondition? = nil,
+        maxTemperature: Int? = nil,
+        minTemperature: Int? = nil,
+        date: Date? = nil,
+        seed: Int? = nil
+    ) -> Response {
+        var generator = SeedRandomNumberGenerator(seed: seed ?? Int.random(in: Int.min...Int.max))
+        let weatherCondition = weatherCondition ?? WeatherCondition.allCases.randomElement(using: &generator)!
+        let maxTemperature = maxTemperature ?? Int.random(in: 10...40, using: &generator)
+        let minTemperature = minTemperature ?? Int.random(in: -40..<maxTemperature, using: &generator)
+        let date = date ?? Date()
+
+        return Response(
+            weatherCondition: weatherCondition.rawValue,
+            maxTemperature: maxTemperature,
+            minTemperature: minTemperature,
+            date: date
+        )
+    }
+}

From 4a081dacb3d9422fe6db1758ec1dd3c8bb9590ec Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Wed, 1 May 2024 22:38:48 +0900
Subject: [PATCH 15/24] Revert "edit: rename callbackFetchWeatherList to
 fetchWeather"

This reverts commit 8ba2766b83aea8e21509ae02e8b55b81be7c5751.
---
 Sources/YumemiWeather/YumemiWeather.swift         | 4 ++--
 Sources/YumemiWeather/YumemiWeatherList.swift     | 4 ++--
 Tests/YumemiWeatherTests/YumemiWeatherTests.swift | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index 18b97d1..bcd91ff 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -129,7 +129,7 @@ final public class YumemiWeather {
     /// - Parameters:
     ///   - jsonString: 地域と日付を含む JSON 文字列
     ///   - completion: 完了コールバック
-    public static func fetchWeather(_ jsonString: String, completion: @escaping (Result<String, YumemiWeatherError>) -> Void) {
+    public static func callbackFetchWeather(_ jsonString: String, completion: @escaping (Result<String, YumemiWeatherError>) -> Void) {
         DispatchQueue.global().asyncAfter(deadline: .now() + apiDuration) {
             do {
                 let response = try fetchWeather(jsonString)
@@ -168,7 +168,7 @@ final public class YumemiWeather {
     @available(iOS 13, macOS 10.15, *)
     public static func asyncFetchWeather(_ jsonString: String) async throws -> String {
         return try await withCheckedThrowingContinuation { continuation in
-            fetchWeather(jsonString) { result in
+            callbackFetchWeather(jsonString) { result in
                 continuation.resume(with: result)
             }
         }
diff --git a/Sources/YumemiWeather/YumemiWeatherList.swift b/Sources/YumemiWeather/YumemiWeatherList.swift
index 9ff9902..c54a5f1 100644
--- a/Sources/YumemiWeather/YumemiWeatherList.swift
+++ b/Sources/YumemiWeather/YumemiWeatherList.swift
@@ -136,7 +136,7 @@ public extension YumemiWeather {
     /// - Parameters:
     ///   - jsonString: 地域と日付を含む JSON 文字列
     ///   - completion: 完了コールバック
-    static func fetchWeatherList(_ jsonString: String, completion: @escaping (Result<String, YumemiWeatherError>) -> Void) {
+    static func callbackFetchWeatherList(_ jsonString: String, completion: @escaping (Result<String, YumemiWeatherError>) -> Void) {
         DispatchQueue.global().asyncAfter(deadline: .now() + apiDuration) {
             do {
                 let response = try fetchWeatherList(jsonString)
@@ -178,7 +178,7 @@ public extension YumemiWeather {
     @available(iOS 13, macOS 10.15, *)
     static func asyncFetchWeatherList(_ jsonString: String) async throws -> String {
         return try await withCheckedThrowingContinuation { continuation in
-            fetchWeatherList(jsonString) { result in
+            callbackFetchWeatherList(jsonString) { result in
                 continuation.resume(with: result)
             }
         }
diff --git a/Tests/YumemiWeatherTests/YumemiWeatherTests.swift b/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
index 322a95c..92468f9 100644
--- a/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
+++ b/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
@@ -80,7 +80,7 @@ final class YumemiWeatherTests: XCTestCase {
 }
 """
         let exp = expectation(description: #function)
-        YumemiWeather.fetchWeather(parameter) { result in
+        YumemiWeather.callbackFetchWeather(parameter) { result in
             exp.fulfill()
             switch result {
             case .success(let jsonString):

From 6965ed4f3571be999acf5da8c2ede7f7118fffa4 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Thu, 2 May 2024 13:40:20 +0900
Subject: [PATCH 16/24] =?UTF-8?q?=E4=B8=8D=E5=BF=85=E8=A6=81=E3=81=AA?=
 =?UTF-8?q?=E5=90=8D=E5=89=8D=E7=A9=BA=E9=96=93=E3=81=AE=E6=8C=87=E5=AE=9A?=
 =?UTF-8?q?=E3=82=92=E5=89=8A=E9=99=A4=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F?=
 =?UTF-8?q?=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Sources/YumemiWeather/YumemiWeather.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index bcd91ff..0f462d5 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -18,7 +18,7 @@ enum WeatherCondition: String, CaseIterable {
     case rainy
 }
 
-public enum YumemiWeatherError: Swift.Error {
+public enum YumemiWeatherError: Error {
     case invalidParameterError
     case unknownError
 }

From ddef52828b6fef1d6dcef0f4a868a1299878bf1a Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Thu, 2 May 2024 15:55:14 +0900
Subject: [PATCH 17/24] =?UTF-8?q?=E3=82=A8=E3=83=B3=E3=82=B3=E3=83=BC?=
 =?UTF-8?q?=E3=83=89=E3=81=95=E3=82=8C=E3=81=9F=E3=82=82=E3=81=AE=E3=81=8C?=
 =?UTF-8?q?=E9=81=A9=E5=88=87=E3=81=AB=E3=83=87=E3=82=B3=E3=83=BC=E3=83=89?=
 =?UTF-8?q?=E3=81=A7=E3=81=8D=E3=82=8B=E3=82=88=E3=81=86=E3=81=AB=E4=BF=AE?=
 =?UTF-8?q?=E6=AD=A3=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Sources/YumemiWeather/YumemiWeather.swift | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index 0f462d5..8d662de 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -187,6 +187,7 @@ extension YumemiWeather {
 
     static let decoder: JSONDecoder = {
         let decoder = JSONDecoder()
+        decoder.keyDecodingStrategy = .convertFromSnakeCase
         decoder.dateDecodingStrategy = .formatted(dateFormatter)
         return decoder
     }()

From 691177484ca71cacd380e7735bd1e535a7a9be9b Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Thu, 2 May 2024 16:46:38 +0900
Subject: [PATCH 18/24] =?UTF-8?q?=E4=B9=B1=E6=95=B0=E7=94=9F=E6=88=90?=
 =?UTF-8?q?=E5=99=A8=E3=81=8C=E7=8B=AC=E8=87=AA=E5=AE=9A=E7=BE=A9=E3=81=95?=
 =?UTF-8?q?=E3=82=8C=E3=81=A6=E3=81=84=E3=82=8B=E3=81=93=E3=81=A8=E3=81=8C?=
 =?UTF-8?q?=E6=83=B3=E5=83=8F=E3=81=97=E3=82=84=E3=81=99=E3=81=84=E5=90=8D?=
 =?UTF-8?q?=E5=89=8D=20ControllableGenerator=20=E3=81=AB=E5=A4=89=E6=9B=B4?=
 =?UTF-8?q?=E3=81=97=E3=80=81=E3=81=9D=E3=81=AE=E6=B8=A1=E3=81=97=E6=96=B9?=
 =?UTF-8?q?=E3=82=92=E6=A8=99=E6=BA=96=E3=83=A9=E3=82=A4=E3=83=96=E3=83=A9?=
 =?UTF-8?q?=E3=83=AA=E3=83=BC=E3=81=AB=E6=B2=BF=E3=81=A3=E3=81=9F=E6=96=B9?=
 =?UTF-8?q?=E6=B3=95=E3=81=AB=E5=A4=89=E6=9B=B4=E3=81=97=E3=81=BE=E3=81=97?=
 =?UTF-8?q?=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

意図した乱数を作り出すために makeRandomResponse に seed を渡す設計になっていましたが、現在の標準ライブラリーでは some RandomNumberGenerator を渡すのが一般的のため、それに合わせました。

また、seed によって乱数が制御されることは ControllableGenerator 器固有の仕様なため、makeRandomResponse には渡さず、それを ControllableGenerator 自身が制御するようにしました。この際、内部で使われる srand48 関数はグローバルに影響するため、イニシャライザーで呼び出すとほかのインスタンスにも影響します。その性質を考慮して、ControllableGenerator はシングルトンで実装するようにしました。

加えて、seed のリセットも ControllableGenerator の範疇と思われるため、必要な値を受け取って適切にシードをリセットする機能もここに移動しました。

その他として、シングルトンを static var で保持させています。これは乱数生成器を各種 API が inout で受け取る仕様になっているため、そこにそのまま渡せるようにするための措置です。自由に書き換え可能にはなりますが、そもそもインスタンスが１つしか存在せず、そのイニシャライザーはプライベートで保護されているため、予期しないインスタンスの入れ替え操作は起こりません。
---
 .../YumemiWeather/ControllableGenerator.swift | 56 +++++++++++++++++++
 .../SeedRandomNumberGenerator.swift           | 19 -------
 Sources/YumemiWeather/YumemiWeather.swift     | 23 ++++++--
 Sources/YumemiWeather/YumemiWeatherList.swift | 10 ++--
 .../YumemiWeatherListTests.swift              | 21 +++++++
 .../YumemiWeatherTests.swift                  | 41 ++++++++++++++
 6 files changed, 140 insertions(+), 30 deletions(-)
 create mode 100644 Sources/YumemiWeather/ControllableGenerator.swift
 delete mode 100644 Sources/YumemiWeather/SeedRandomNumberGenerator.swift

diff --git a/Sources/YumemiWeather/ControllableGenerator.swift b/Sources/YumemiWeather/ControllableGenerator.swift
new file mode 100644
index 0000000..d7f5d08
--- /dev/null
+++ b/Sources/YumemiWeather/ControllableGenerator.swift
@@ -0,0 +1,56 @@
+//
+//  ControllableGenerator.swift
+//
+//
+//  Created by 古宮 伸久 on 2022/04/08.
+//
+
+import Foundation
+
+/// 制御可能な乱数生成器です。
+struct ControllableGenerator {
+    
+    /// 唯一のインスタンスを生成します。
+    ///
+    /// このイニシャライザーは、複数回呼び出しても意味がありません。
+    /// 乱数生成方法の都合で、同じ振る舞いをするインスタンスになります。
+    private init() {
+    }
+}
+
+extension ControllableGenerator {
+    
+    /// 唯一の、制御可能な乱数生成器インスタンスです。
+    static var shared = ControllableGenerator()
+    
+    /// 乱数生成時に使用するシード値を `seed` でリセットします。
+    /// - Parameter seed: 新たに使用するシード値です。
+    static func reset(withSeed seed: Int) {
+        srand48(seed)
+    }
+    
+    /// 乱数生成時に使用するシード値を `area` と `date` から算出してリセットします。
+    /// - Parameters:
+    ///   - area: シード値の算出に使う、地域情報
+    ///   - date: シード値の算出に使う、日付情報
+    static func resetUsing(area: Area, date: Date) {
+        
+        var hasher = Hasher()
+        
+        hasher.combine(area)
+        hasher.combine(date)
+        
+        let seed = hasher.finalize()
+        
+        reset(withSeed: seed)
+    }
+}
+
+extension ControllableGenerator : RandomNumberGenerator {
+    
+    /// 次の乱数を生成します。
+    /// - Returns: 次の乱数です。
+    func next() -> UInt64 {
+        UInt64(drand48() * Double(UInt64.max))
+    }
+}
diff --git a/Sources/YumemiWeather/SeedRandomNumberGenerator.swift b/Sources/YumemiWeather/SeedRandomNumberGenerator.swift
deleted file mode 100644
index 1c3c5da..0000000
--- a/Sources/YumemiWeather/SeedRandomNumberGenerator.swift
+++ /dev/null
@@ -1,19 +0,0 @@
-//
-//  SeedRandomNumberGenerator.swift
-//
-//
-//  Created by 古宮 伸久 on 2022/04/08.
-//
-
-import Foundation
-
-struct SeedRandomNumberGenerator: RandomNumberGenerator {
-    init(seed: Int) {
-        // Set the random seed
-        srand48(seed)
-    }
-
-    func next() -> UInt64 {
-        UInt64(drand48() * Double(UInt64.max))
-    }
-}
diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index 8d662de..f69b3f8 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -205,17 +205,30 @@ extension YumemiWeather {
     ///   - maxTemperature: 最高気温
     ///   - minTemperature: 最低気温
     ///   - date: 日付
-    ///   - seed: シード値
     /// - Returns: Response構造体
-
     static func makeRandomResponse(
         weatherCondition: WeatherCondition? = nil,
         maxTemperature: Int? = nil,
         minTemperature: Int? = nil,
-        date: Date? = nil,
-        seed: Int? = nil
+        date: Date? = nil
+    ) -> Response {
+        return makeRandomResponse(using: &ControllableGenerator.shared, weatherCondition: weatherCondition, maxTemperature: maxTemperature, minTemperature: minTemperature)
+    }
+    
+    /// 引数の値でResponse構造体を作成する。引数がnilの場合はランダムに値を作成する。
+    /// - Parameters:
+    ///   - weatherCondition: 天気状況を表すenum
+    ///   - maxTemperature: 最高気温
+    ///   - minTemperature: 最低気温
+    ///   - date: 日付
+    /// - Returns: Response構造体
+    static func makeRandomResponse(
+        using generator: inout some RandomNumberGenerator,
+        weatherCondition: WeatherCondition? = nil,
+        maxTemperature: Int? = nil,
+        minTemperature: Int? = nil,
+        date: Date? = nil
     ) -> Response {
-        var generator = SeedRandomNumberGenerator(seed: seed ?? Int.random(in: Int.min...Int.max))
         let weatherCondition = weatherCondition ?? WeatherCondition.allCases.randomElement(using: &generator)!
         let maxTemperature = maxTemperature ?? Int.random(in: 10...40, using: &generator)
         let minTemperature = minTemperature ?? Int.random(in: -40..<maxTemperature, using: &generator)
diff --git a/Sources/YumemiWeather/YumemiWeatherList.swift b/Sources/YumemiWeather/YumemiWeatherList.swift
index c54a5f1..0a7c29d 100644
--- a/Sources/YumemiWeather/YumemiWeatherList.swift
+++ b/Sources/YumemiWeather/YumemiWeatherList.swift
@@ -69,13 +69,11 @@ public extension YumemiWeather {
         }
 
         let areas = request.areas.isEmpty ? Area.allCases : request.areas.compactMap { Area(rawValue: $0) }
-        let response = areas.map { area -> AreaResponse in
-            var hasher = Hasher()
-            hasher.combine(area)
-            hasher.combine(request.date)
-            return AreaResponse(area: area, info: makeRandomResponse(date: request.date, seed: hasher.finalize()))
+        let areaResponses = areas.map { area -> AreaResponse in
+            ControllableGenerator.resetUsing(area: area, date: request.date)
+            return AreaResponse(area: area, info: makeRandomResponse(using: &ControllableGenerator.shared, date: request.date))
         }
-        let responseData = try encoder.encode(response)
+        let responseData = try encoder.encode(areaResponses)
 
         return String(data: responseData, encoding: .utf8)!
     }
diff --git a/Tests/YumemiWeatherTests/YumemiWeatherListTests.swift b/Tests/YumemiWeatherTests/YumemiWeatherListTests.swift
index eb1ee51..2b75646 100644
--- a/Tests/YumemiWeatherTests/YumemiWeatherListTests.swift
+++ b/Tests/YumemiWeatherTests/YumemiWeatherListTests.swift
@@ -3,6 +3,27 @@ import XCTest
 
 final class YumemiWeatherListTests: XCTestCase {
 
+    func test_Areasに空を指定したときに全ての地域が取得される() throws {
+        
+        let request = """
+        {
+            "areas": [],
+            "date": "2020-04-01T12:00:00+09:00"
+        }
+        """
+        
+        let responseJSON = try YumemiWeather.fetchWeatherList(request)
+        
+        guard let responseData = responseJSON.data(using: .utf8) else {
+            XCTFail("Illegal response data: \(responseJSON)")
+            return
+        }
+        
+        let response = try YumemiWeather.decoder.decode([AreaResponse].self, from: responseData)
+        
+        XCTAssertEqual(response.map(\.area), Area.allCases)
+    }
+    
     func test_fetchWeatherList_jsonString() {
         let parameter = """
 {
diff --git a/Tests/YumemiWeatherTests/YumemiWeatherTests.swift b/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
index 92468f9..eab6d6f 100644
--- a/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
+++ b/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
@@ -3,6 +3,47 @@ import XCTest
 
 final class YumemiWeatherTests: XCTestCase {
 
+    func test_ランダムにレスポンスを生成する() {
+
+        // 日付を省略すると実行した瞬間のものが得られてしまうため、
+        // テストするために固定とします。
+        let date = Date()
+        
+        func makeRandomResponse(withSeed seed: Int) -> Response {
+            
+            ControllableGenerator.reset(withSeed: seed)
+            return YumemiWeather.makeRandomResponse(using: &ControllableGenerator.shared, date: date)
+        }
+
+        let response1 = makeRandomResponse(withSeed: 0)
+        let response2 = makeRandomResponse(withSeed: 1546000)
+        let response3 = makeRandomResponse(withSeed: 0)
+        let response4 = makeRandomResponse(withSeed: 1546000)
+
+        XCTAssertEqual(response1, response3)
+        XCTAssertEqual(response2, response4)
+        
+        XCTAssertEqual(response1.weatherCondition, "sunny")
+        XCTAssertEqual(response1.minTemperature, -33)
+        XCTAssertEqual(response1.maxTemperature, 33)
+        XCTAssertEqual(response1.date, date)
+        
+        XCTAssertEqual(response2.weatherCondition, "cloudy")
+        XCTAssertEqual(response2.minTemperature, 23)
+        XCTAssertEqual(response2.maxTemperature, 28)
+        XCTAssertEqual(response2.date, date)
+        
+        XCTAssertEqual(response3.weatherCondition, "sunny")
+        XCTAssertEqual(response3.minTemperature, -33)
+        XCTAssertEqual(response3.maxTemperature, 33)
+        XCTAssertEqual(response3.date, date)
+        
+        XCTAssertEqual(response4.weatherCondition, "cloudy")
+        XCTAssertEqual(response4.minTemperature, 23)
+        XCTAssertEqual(response4.maxTemperature, 28)
+        XCTAssertEqual(response4.date, date)
+    }
+    
     func test_fetchWeather() {
         let str = YumemiWeather.fetchWeatherCondition()
         XCTAssertNotNil(WeatherCondition(rawValue: str))

From 121b753658d1b8c80e1b809b8811edcae03c4d83 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Thu, 2 May 2024 16:55:52 +0900
Subject: [PATCH 19/24] =?UTF-8?q?=E6=A8=99=E6=BA=96=E3=83=A9=E3=82=A4?=
 =?UTF-8?q?=E3=83=96=E3=83=A9=E3=83=AA=E3=83=BC=E3=81=AE=E4=BD=9C=E6=B3=95?=
 =?UTF-8?q?=E3=81=AB=E5=9F=BA=E3=81=A5=E3=81=84=E3=81=A6=E3=80=81WeatherCo?=
 =?UTF-8?q?ndition=20=E3=82=92=E3=83=A9=E3=83=B3=E3=83=80=E3=83=A0?=
 =?UTF-8?q?=E3=81=A7=E7=94=9F=E6=88=90=E3=81=99=E3=82=8B=E3=82=B3=E3=83=BC?=
 =?UTF-8?q?=E3=83=89=E3=82=92=E5=A4=89=E6=9B=B4=E3=81=97=E3=81=BE=E3=81=97?=
 =?UTF-8?q?=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Sources/YumemiWeather/YumemiWeather.swift | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index f69b3f8..db43983 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -18,6 +18,22 @@ enum WeatherCondition: String, CaseIterable {
     case rainy
 }
 
+extension WeatherCondition {
+    
+    /// 天候をランダムで取得します。
+    /// - Returns: なにかしらの転向を返します。
+    static func random() -> Self {
+        random(using: &ControllableGenerator.shared)
+    }
+    
+    /// 天候をランダムで取得します。
+    /// - Parameter generator: ランダムで取得するのに使う乱数生成期です。
+    /// - Returns: なにかしらの転向を返します。
+    static func random(using generator: inout some RandomNumberGenerator) -> Self {
+        WeatherCondition.allCases.randomElement(using: &generator)!
+    }
+}
+
 public enum YumemiWeatherError: Error {
     case invalidParameterError
     case unknownError
@@ -229,7 +245,7 @@ extension YumemiWeather {
         minTemperature: Int? = nil,
         date: Date? = nil
     ) -> Response {
-        let weatherCondition = weatherCondition ?? WeatherCondition.allCases.randomElement(using: &generator)!
+        let weatherCondition = weatherCondition ?? WeatherCondition.random(using: &generator)
         let maxTemperature = maxTemperature ?? Int.random(in: 10...40, using: &generator)
         let minTemperature = minTemperature ?? Int.random(in: -40..<maxTemperature, using: &generator)
         let date = date ?? Date()

From 3193e2768ae8ef3837a54e7256a9e1b804db7a11 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Thu, 2 May 2024 17:38:16 +0900
Subject: [PATCH 20/24] =?UTF-8?q?=E4=B8=8D=E5=BF=85=E8=A6=81=E3=81=AA?=
 =?UTF-8?q?=E5=90=8D=E5=89=8D=E7=A9=BA=E9=96=93=E6=8C=87=E5=AE=9A=E3=82=92?=
 =?UTF-8?q?=E5=89=8A=E9=99=A4=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Sources/YumemiWeather/YumemiWeather.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index db43983..b9a0f81 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -30,7 +30,7 @@ extension WeatherCondition {
     /// - Parameter generator: ランダムで取得するのに使う乱数生成期です。
     /// - Returns: なにかしらの転向を返します。
     static func random(using generator: inout some RandomNumberGenerator) -> Self {
-        WeatherCondition.allCases.randomElement(using: &generator)!
+        allCases.randomElement(using: &generator)!
     }
 }
 

From 718cc61d1483bdf97e0f53d00bdbe71debcdeec3 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Fri, 3 May 2024 00:20:29 +0900
Subject: [PATCH 21/24] =?UTF-8?q?=E3=83=89=E3=82=AD=E3=83=A5=E3=83=A1?=
 =?UTF-8?q?=E3=83=B3=E3=83=88=E3=82=B3=E3=83=A1=E3=83=B3=E3=83=88=E3=81=AE?=
 =?UTF-8?q?=E8=AA=A4=E5=AD=97=E3=82=92=E4=BF=AE=E6=AD=A3=E3=81=97=E3=81=BE?=
 =?UTF-8?q?=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Sources/YumemiWeather/YumemiWeather.swift | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index b9a0f81..0b312ca 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -21,14 +21,14 @@ enum WeatherCondition: String, CaseIterable {
 extension WeatherCondition {
     
     /// 天候をランダムで取得します。
-    /// - Returns: なにかしらの転向を返します。
+    /// - Returns: なにかしらの天候を返します。
     static func random() -> Self {
         random(using: &ControllableGenerator.shared)
     }
     
     /// 天候をランダムで取得します。
     /// - Parameter generator: ランダムで取得するのに使う乱数生成期です。
-    /// - Returns: なにかしらの転向を返します。
+    /// - Returns: なにかしらの天候を返します。
     static func random(using generator: inout some RandomNumberGenerator) -> Self {
         allCases.randomElement(using: &generator)!
     }

From feee4401e34b2edad455ef49e932ee9e4aa8b6f5 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Fri, 3 May 2024 00:32:41 +0900
Subject: [PATCH 22/24] =?UTF-8?q?=E4=B8=8D=E5=BF=85=E8=A6=81=E3=81=AA?=
 =?UTF-8?q?=E5=90=8D=E5=89=8D=E7=A9=BA=E9=96=93=E3=81=AE=E6=98=8E=E8=A8=98?=
 =?UTF-8?q?=E3=82=92=E7=9C=81=E7=95=A5=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F?=
 =?UTF-8?q?=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Sources/YumemiWeather/YumemiWeather.swift | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index 0b312ca..aae67cb 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -245,9 +245,9 @@ extension YumemiWeather {
         minTemperature: Int? = nil,
         date: Date? = nil
     ) -> Response {
-        let weatherCondition = weatherCondition ?? WeatherCondition.random(using: &generator)
-        let maxTemperature = maxTemperature ?? Int.random(in: 10...40, using: &generator)
-        let minTemperature = minTemperature ?? Int.random(in: -40..<maxTemperature, using: &generator)
+        let weatherCondition = weatherCondition ?? .random(using: &generator)
+        let maxTemperature = maxTemperature ?? .random(in: 10...40, using: &generator)
+        let minTemperature = minTemperature ?? .random(in: -40..<maxTemperature, using: &generator)
         let date = date ?? Date()
 
         return Response(

From 6d986e1664c003fb01100cb66f990927584efcb6 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <t_kumagai@yumemi.co.jp>
Date: Thu, 9 May 2024 22:22:29 +0900
Subject: [PATCH 23/24] =?UTF-8?q?YumemiWeather=20=E3=81=AE=20List=20?=
 =?UTF-8?q?=E5=8F=96=E5=BE=97=E7=94=A8=20API=20=E3=81=A7=E3=80=81=E5=9C=B0?=
 =?UTF-8?q?=E5=9F=9F=E3=81=AB=E7=A9=BA=E3=82=92=E6=8C=87=E5=AE=9A=E3=81=99?=
 =?UTF-8?q?=E3=82=8B=E3=81=A8=E5=85=A8=E5=9C=B0=E5=9F=9F=E3=81=AE=E4=BA=88?=
 =?UTF-8?q?=E5=A0=B1=E3=81=8C=E5=8F=96=E5=BE=97=E3=81=A7=E3=81=8D=E3=82=8B?=
 =?UTF-8?q?=E6=97=A8=E3=82=92=E3=83=89=E3=82=AD=E3=83=A5=E3=83=A1=E3=83=B3?=
 =?UTF-8?q?=E3=83=88=E3=82=B3=E3=83=A1=E3=83=B3=E3=83=88=E3=81=AB=E8=A8=98?=
 =?UTF-8?q?=E8=BC=89=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82=E6=93=AC?=
 =?UTF-8?q?=E4=BC=BC=20API=20=E3=81=A7=E3=81=82=E3=82=8B=E3=81=93=E3=81=A8?=
 =?UTF-8?q?=E3=81=AE=E8=A8=98=E8=BF=B0=E3=82=92=E5=90=84=20API=20=E3=81=A7?=
 =?UTF-8?q?=E3=81=AF=E3=81=AA=E3=81=8F=20YumemiWeather=20=E5=9E=8B?=
 =?UTF-8?q?=E3=81=AE=E3=83=89=E3=82=AD=E3=83=A5=E3=83=A1=E3=83=B3=E3=83=88?=
 =?UTF-8?q?=E3=82=B3=E3=83=A1=E3=83=B3=E3=83=88=E3=81=AB=E8=A8=98=E8=BC=89?=
 =?UTF-8?q?=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82=E3=81=9D=E3=82=8C?=
 =?UTF-8?q?=E3=81=AB=E4=BC=B4=E3=81=84=E3=80=81=E5=8D=98=E4=BD=93=E5=8F=96?=
 =?UTF-8?q?=E5=BE=97=E7=94=A8=E3=81=AE=20API=20=E3=81=A7=E3=81=AE=E3=83=89?=
 =?UTF-8?q?=E3=82=AD=E3=83=A5=E3=83=A1=E3=83=B3=E3=83=88=E3=82=B3=E3=83=A1?=
 =?UTF-8?q?=E3=83=B3=E3=83=88=E3=82=82=E8=AA=BF=E6=95=B4=E3=81=97=E3=80=81?=
 =?UTF-8?q?=E5=85=A8=E4=BD=93=E3=81=AB=E7=B5=B1=E4=B8=80=E6=84=9F=E3=82=92?=
 =?UTF-8?q?=E6=8C=81=E3=81=9F=E3=81=9B=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Sources/YumemiWeather/YumemiWeather.swift     | 29 +++++++++++++++----
 Sources/YumemiWeather/YumemiWeatherList.swift | 29 ++++++++++++++++---
 2 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index aae67cb..6e69d86 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -39,15 +39,20 @@ public enum YumemiWeatherError: Error {
     case unknownError
 }
 
+/// 天気予報を取得する擬似天気予報 API です。
+///
+/// ゆめみ iOS 研修用の実装であり、実際の天気予報ではなくランダムな天気予報が得られます。
+/// 研修効果を高めるため、さまざまなバージョンの API が用意されていて、
+/// その中には適切なパラメーターを与えたときでも一定の確率でエラーを返すものもあります。
 final public class YumemiWeather {
 
-    /// 擬似 天気予報 API Simple ver
+    /// 天気予報を読み込む API の Simple Version です。
     /// - Returns: 天気状況を表す文字列 "sunny" or "cloudy" or "rainy"
     public static func fetchWeatherCondition() -> String {
         return makeRandomResponse().weatherCondition
     }
 
-    /// 擬似 天気予報 API Throws ver
+    /// 天気予報を読み込む API の Throwing Version です。
     /// - Throws: YumemiWeatherError
     /// - Parameters:
     ///   - area: 天気予報を取得する対象地域 example: "tokyo"
@@ -60,7 +65,10 @@ final public class YumemiWeather {
         return makeRandomResponse().weatherCondition
     }
 
-    /// 擬似 天気予報 API JSON ver
+    /// 天気予報を読み込む API の JSON Version です。
+    ///
+    /// JSON 文字列で地域情報 `area` と日付情報 `date` を持つオブジェクトを受け取って、それに該当する天気予報を取得します。
+    /// 取得された天気予報は速やかに返されます。
     ///
     /// API に請求する JSON 文字列の例：
     ///
@@ -97,7 +105,10 @@ final public class YumemiWeather {
         return String(data: responseData, encoding: .utf8)!
     }
 
-    /// 擬似 天気予報 API Sync ver
+    /// 天気予報を読み込む API の Sync Version です。
+    ///
+    /// JSON 文字列で地域情報 `area` と日付情報 `date` を持つオブジェクトを受け取って、それに該当する天気予報を取得します。
+    /// この API は同期的に実行され、天気予報を返すまでに若干時間がかかります。
     ///
     /// API に請求する JSON 文字列の例：
     ///
@@ -123,7 +134,10 @@ final public class YumemiWeather {
         return try fetchWeather(jsonString)
     }
     
-    /// 擬似 天気予報 API Callback ver
+    /// 天気予報を読み込む API の Callback Version です。
+    ///
+    /// JSON 文字列で地域情報 `area` と日付情報 `date` を持つオブジェクトを受け取って、それに該当する天気予報を取得します。
+    /// この API は非同期的に実行され、天気予報を取得できるとその結果を添えて `completion` を呼び出します。
     ///
     /// API に請求する JSON 文字列の例：
     ///
@@ -160,8 +174,11 @@ final public class YumemiWeather {
         }
     }
 
-    /// 擬似 天気予報 API Async ver
+    /// 天気予報を読み込む API の Async Version です。
     ///
+    /// JSON 文字列で地域情報 `area` と日付情報 `date` を持つオブジェクトを受け取って、それに該当する天気予報を取得します。
+    /// この API は非同期的に実行され、天気予報を取得できるまでは Swift Concurrency により処理が中断されます。
+    /// 
     /// API に請求する JSON 文字列の例：
     ///
     ///     {
diff --git a/Sources/YumemiWeather/YumemiWeatherList.swift b/Sources/YumemiWeather/YumemiWeatherList.swift
index 0a7c29d..45fd4a9 100644
--- a/Sources/YumemiWeather/YumemiWeatherList.swift
+++ b/Sources/YumemiWeather/YumemiWeatherList.swift
@@ -34,7 +34,12 @@ public enum Area: String, CaseIterable, Codable {
 
 public extension YumemiWeather {
 
-    /// 擬似 天気予報一覧 API JSON ver
+    /// 天気予報一覧を読み込む API の JSON Version です。
+    ///
+    /// JSON 文字列で地域情報 `areas` と日付情報 `date` を持つオブジェクトを受け取って、それに該当する天気予報を取得します。
+    /// 取得された天気予報は速やかに返されます。
+    ///
+    /// 地域情報は配列で複数の地域を一括指定し、それらの地域の天気予報を取得できます。地域を指定しない場合は全地域の天気予報を取得します。
     ///
     /// API に請求する JSON 文字列の例：
     ///
@@ -42,6 +47,7 @@ public extension YumemiWeather {
     ///         "areas": ["Tokyo"],
     ///         "date": "2020-04-01T12:00:00+09:00"
     ///     }
+    ///
     /// 返された AreaResponse の JSON 文字列の例
     ///
     ///     [
@@ -78,7 +84,12 @@ public extension YumemiWeather {
         return String(data: responseData, encoding: .utf8)!
     }
 
-    /// 擬似 天気予報一覧 API Sync ver
+    /// 天気予報一覧を読み込む API の Sync Version です。
+    ///
+    /// JSON 文字列で地域情報 `areas` と日付情報 `date` を持つオブジェクトを受け取って、それに該当する天気予報を取得します。
+    /// この API は同期的に実行され、天気予報を返すまでに若干時間がかかります。
+    ///
+    /// 地域情報は配列で複数の地域を一括指定し、それらの地域の天気予報を取得できます。地域を指定しない場合は全地域の天気予報を取得します。
     ///
     /// API に請求する JSON 文字列の例：
     ///
@@ -107,7 +118,12 @@ public extension YumemiWeather {
         return try fetchWeatherList(jsonString)
     }
 
-    /// 擬似 天気予報一覧 API Callback ver
+    /// 天気予報一覧を読み込む API の Callback Version です。
+    ///
+    /// JSON 文字列で地域情報 `areas` と日付情報 `date` を持つオブジェクトを受け取って、それに該当する天気予報を取得します。
+    /// この API は非同期的に実行され、天気予報を取得できるとその結果を添えて `completion` を呼び出します。
+    ///
+    /// 地域情報は配列で複数の地域を一括指定し、それらの地域の天気予報を取得できます。地域を指定しない場合は全地域の天気予報を取得します。
     ///
     /// API に請求する JSON 文字列の例：
     ///
@@ -149,7 +165,12 @@ public extension YumemiWeather {
         }
     }
 
-    /// 擬似 天気予報一覧API Async ver
+    /// 天気予報一覧を読み込む API の Async Version です。
+    ///
+    /// JSON 文字列で地域情報 `areas` と日付情報 `date` を持つオブジェクトを受け取って、それに該当する天気予報を取得します。
+    /// この API は非同期的に実行され、天気予報を取得できるまでは Swift Concurrency により処理が中断されます。
+    ///
+    /// 地域情報は配列で複数の地域を一括指定し、それらの地域の天気予報を取得できます。地域を指定しない場合は全地域の天気予報を取得します。
     ///
     /// API に請求する JSON 文字列の例：
     ///

From 9cfb85bcd4faa31d99ef6c0f430c634590ce49c2 Mon Sep 17 00:00:00 2001
From: Tomohiro Kumagai <tomo@ez-net.jp>
Date: Thu, 2 May 2024 22:43:16 +0900
Subject: [PATCH 24/24] =?UTF-8?q?YumemiWeather=20API=20=E3=81=8C=E7=84=A1?=
 =?UTF-8?q?=E4=BD=9C=E7=82=BA=E3=81=AB=E3=82=A8=E3=83=A9=E3=83=BC=E3=82=92?=
 =?UTF-8?q?=E8=BF=94=E3=81=99=E9=A0=BB=E5=BA=A6=E3=82=92=E3=82=B3=E3=83=B3?=
 =?UTF-8?q?=E3=83=88=E3=83=AD=E3=83=BC=E3=83=AB=E5=8F=AF=E8=83=BD=E3=81=AB?=
 =?UTF-8?q?=E3=81=97=E3=81=BE=E3=81=97=E3=81=9F=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../YumemiWeather.APIQuality.swift            |  54 +++++++
 Sources/YumemiWeather/YumemiWeather.swift     |  12 +-
 Sources/YumemiWeather/YumemiWeatherList.swift |   4 +-
 Tests/YumemiWeatherTests/TestMethods.swift    |  67 ++++++++
 .../YumemiWeatherListTests.swift              | 150 ++++++++----------
 .../YumemiWeatherTests.swift                  |  90 ++++-------
 6 files changed, 226 insertions(+), 151 deletions(-)
 create mode 100644 Sources/YumemiWeather/YumemiWeather.APIQuality.swift
 create mode 100644 Tests/YumemiWeatherTests/TestMethods.swift

diff --git a/Sources/YumemiWeather/YumemiWeather.APIQuality.swift b/Sources/YumemiWeather/YumemiWeather.APIQuality.swift
new file mode 100644
index 0000000..2a059f3
--- /dev/null
+++ b/Sources/YumemiWeather/YumemiWeather.APIQuality.swift
@@ -0,0 +1,54 @@
+//
+//  YumemiWeather.APIQuality.swift
+//
+//  
+//  Created by Tomohiro Kumagai on 2024/05/02
+//  
+//
+
+extension YumemiWeather {
+    
+    /// API の品質を表現します。
+    enum APIQuality {
+        case sometimesFails(probability: Double)
+        case alwaysFails
+        case neverFails
+    }
+}
+
+extension YumemiWeather {
+    
+    /// API の想定品質です。
+    static var apiQuality: APIQuality = .sometimesFails(probability: 0.25)
+    
+    static func whetherHit(with probability: Double) -> Bool {
+        return (0 ..< probability).contains(.random(in: 0 ..< 1))
+    }
+    
+    /// この場所に不安定要素を埋め込みます。
+    ///
+    /// 不安定さの度合いは `apiQuality` に依存します。
+    /// - Throws: YumemiError ここで失敗が生成されると YumemiWeatherError.unknownError が送出されます。
+    static func introduceInstability() throws {
+        
+        switch apiQuality {
+
+        case .neverFails:
+            return
+
+        case .sometimesFails(let probability) where !whetherHit(with: probability):
+            return
+
+        case .sometimesFails, .alwaysFails:
+            throw YumemiWeatherError.unknownError
+        }
+    }
+    
+    /// この場所に不安定要素を埋め込みます。
+    ///
+    /// 不安定さの度合いは `apiQuality` に依存します。
+    /// - Throws: YumemiError ここで失敗が生成されると YumemiWeatherError.unknownError が送出されます。
+    func introduceInstability() throws {
+        try Self.introduceInstability()
+    }
+}
diff --git a/Sources/YumemiWeather/YumemiWeather.swift b/Sources/YumemiWeather/YumemiWeather.swift
index 6e69d86..ca3bd46 100644
--- a/Sources/YumemiWeather/YumemiWeather.swift
+++ b/Sources/YumemiWeather/YumemiWeather.swift
@@ -58,11 +58,8 @@ final public class YumemiWeather {
     ///   - area: 天気予報を取得する対象地域 example: "tokyo"
     /// - Returns: 天気状況を表す文字列 "sunny" or "cloudy" or "rainy"
     public static func fetchWeatherCondition(at area: String) throws -> String {
-        if Int.random(in: 0...4) == 4 {
-            throw YumemiWeatherError.unknownError
-        }
-
-        return makeRandomResponse().weatherCondition
+        try introduceInstability()
+        return self.makeRandomResponse().weatherCondition
     }
 
     /// 天気予報を読み込む API の JSON Version です。
@@ -98,10 +95,7 @@ final public class YumemiWeather {
         let response = makeRandomResponse(date: request.date)
         let responseData = try encoder.encode(response)
 
-        if Int.random(in: 0...4) == 4 {
-            throw YumemiWeatherError.unknownError
-        }
-
+        try introduceInstability()
         return String(data: responseData, encoding: .utf8)!
     }
 
diff --git a/Sources/YumemiWeather/YumemiWeatherList.swift b/Sources/YumemiWeather/YumemiWeatherList.swift
index 45fd4a9..7f0ff13 100644
--- a/Sources/YumemiWeather/YumemiWeatherList.swift
+++ b/Sources/YumemiWeather/YumemiWeatherList.swift
@@ -70,9 +70,7 @@ public extension YumemiWeather {
             throw YumemiWeatherError.invalidParameterError
         }
 
-        if Int.random(in: 0...4) == 4 {
-            throw YumemiWeatherError.unknownError
-        }
+        try introduceInstability()
 
         let areas = request.areas.isEmpty ? Area.allCases : request.areas.compactMap { Area(rawValue: $0) }
         let areaResponses = areas.map { area -> AreaResponse in
diff --git a/Tests/YumemiWeatherTests/TestMethods.swift b/Tests/YumemiWeatherTests/TestMethods.swift
new file mode 100644
index 0000000..005e8bf
--- /dev/null
+++ b/Tests/YumemiWeatherTests/TestMethods.swift
@@ -0,0 +1,67 @@
+//
+//  TestMethods.swift
+//
+//  
+//  Created by Tomohiro Kumagai on 2024/05/02
+//  
+//
+
+import XCTest
+@testable import YumemiWeather
+
+/// 失敗数が想定内かを判定します。
+/// - Parameters:
+///   - probability: 失敗率です。
+///   - tryingCount: 総試行回数です。
+///   - failureCount: うち、失敗した回数です。
+///   - file: 判定コードが記載されたファイルです。
+///   - line: 判定コードが記載された行です。
+func XCTAssertFailureCount(probability: Double, tryingCount: Int, failureCount: Int, file: StaticString = #filePath, line: UInt = #line) {
+    
+    let estimatedFailureCount = Double(tryingCount) * probability
+    let expectedFailureMargin = Double(tryingCount) * 0.01
+
+    let expectedFailureRange = estimatedFailureCount - expectedFailureMargin ..< estimatedFailureCount + expectedFailureMargin
+
+    XCTAssertTrue(expectedFailureRange.contains(Double(failureCount)), "Failures: \(failureCount), Estimated failures = \(estimatedFailureCount)±\(expectedFailureMargin)", file: file, line: line)
+}
+
+/// YumemiWether API の品質をテストします。
+/// - Parameters:
+///   - tryingCount: 総試行回数です。
+///   - quality: API の想定品質です。
+///   - file: 判定コードが記載されたファイルです。
+///   - line: 判定コードが記載された行です。
+func XCTAssertAPIQuality(_ predicate: () throws -> Void, tryingCount: Int, quality: YumemiWeather.APIQuality, file: StaticString = #filePath, line: UInt = #line) {
+        
+    var succeededCount = 0
+    var failedCount = 0
+    
+    YumemiWeather.apiQuality = quality
+    
+    for _ in 0 ..< tryingCount {
+
+        switch Result(catching: predicate) {
+            
+        case .success():
+            succeededCount += 1
+            
+        case .failure(_):
+            failedCount += 1
+        }
+    }
+    
+    switch quality {
+        
+    case .neverFails:
+        XCTAssertEqual(succeededCount, tryingCount, file: file, line: line)
+        XCTAssertEqual(failedCount, 0, file: file, line: line)
+        
+    case .alwaysFails:
+        XCTAssertEqual(succeededCount, 0, file: file, line: line)
+        XCTAssertEqual(failedCount, tryingCount, file: file, line: line)
+
+    case .sometimesFails(let probability):
+        XCTAssertFailureCount(probability: probability, tryingCount: tryingCount, failureCount: failedCount, file: file, line: line)
+    }
+}
diff --git a/Tests/YumemiWeatherTests/YumemiWeatherListTests.swift b/Tests/YumemiWeatherTests/YumemiWeatherListTests.swift
index 2b75646..2e50829 100644
--- a/Tests/YumemiWeatherTests/YumemiWeatherListTests.swift
+++ b/Tests/YumemiWeatherTests/YumemiWeatherListTests.swift
@@ -3,6 +3,28 @@ import XCTest
 
 final class YumemiWeatherListTests: XCTestCase {
 
+    override func setUpWithError() throws {
+        YumemiWeather.apiQuality = .neverFails
+    }
+    
+    func test_APIは必ずしも成功しない() throws {
+        
+        let tryingCount = 15_000
+        let request = """
+        {
+            "area": "tokyo",
+            "date": "2020-04-01T12:00:00+09:00"
+        }
+        """
+        let predicate = { _ = try YumemiWeather.fetchWeather(request) }
+
+        XCTAssertAPIQuality(predicate, tryingCount: tryingCount, quality: .sometimesFails(probability: 0.25))
+        XCTAssertAPIQuality(predicate, tryingCount: tryingCount, quality: .sometimesFails(probability: 0.8))
+        XCTAssertAPIQuality(predicate, tryingCount: tryingCount, quality: .sometimesFails(probability: 0.05))
+        XCTAssertAPIQuality(predicate, tryingCount: tryingCount, quality: .alwaysFails)
+        XCTAssertAPIQuality(predicate, tryingCount: tryingCount, quality: .neverFails)
+    }
+    
     func test_Areasに空を指定したときに全ての地域が取得される() throws {
         
         let request = """
@@ -24,115 +46,83 @@ final class YumemiWeatherListTests: XCTestCase {
         XCTAssertEqual(response.map(\.area), Area.allCases)
     }
     
-    func test_fetchWeatherList_jsonString() {
+    func test_fetchWeatherList_jsonString() throws {
         let parameter = """
 {
     "areas": [],
     "date": "2020-04-01T12:00:00+09:00"
 }
 """
-        do {
-            let responseJSON = try YumemiWeather.fetchWeatherList(parameter)
-            let dateFormatter = DateFormatter()
-            dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
-            let decoder = JSONDecoder()
-            decoder.keyDecodingStrategy = .convertFromSnakeCase
-            decoder.dateDecodingStrategy = .formatted(dateFormatter)
-            let response = try decoder.decode([AreaResponse].self, from: Data(responseJSON.utf8))
-            XCTAssertEqual(response.count, Area.allCases.count)
-        }
-        catch let error as YumemiWeatherError {
-            XCTAssertEqual(error, YumemiWeatherError.unknownError)
-        }
-        catch {
-            XCTFail()
-        }
+        let responseJSON = try YumemiWeather.fetchWeatherList(parameter)
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
+        let decoder = JSONDecoder()
+        decoder.keyDecodingStrategy = .convertFromSnakeCase
+        decoder.dateDecodingStrategy = .formatted(dateFormatter)
+        let response = try decoder.decode([AreaResponse].self, from: Data(responseJSON.utf8))
+        XCTAssertEqual(response.count, Area.allCases.count)
     }
 
-    func test_fetchWeatherList_jsonString_one() {
+    func test_fetchWeatherList_jsonString_one() throws {
         let parameter = """
 {
     "areas": ["Tokyo"],
     "date": "2020-04-01T12:00:00+09:00"
 }
 """
-        do {
-            let responseJSON = try YumemiWeather.fetchWeatherList(parameter)
-            let dateFormatter = DateFormatter()
-            dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
-            let decoder = JSONDecoder()
-            decoder.keyDecodingStrategy = .convertFromSnakeCase
-            decoder.dateDecodingStrategy = .formatted(dateFormatter)
-            let response = try decoder.decode([AreaResponse].self, from: Data(responseJSON.utf8))
-            XCTAssertEqual(response.count, 1)
-            let tokyo = response.first
-            XCTAssertEqual(tokyo?.area, .Tokyo)
-
-            let responseJSON2 = try YumemiWeather.fetchWeatherList(parameter)
-            let response2 = try decoder.decode([AreaResponse].self, from: Data(responseJSON2.utf8))
-            let tokyo2 = response2.first
-            XCTAssertEqual(tokyo?.info, tokyo2?.info)
-        }
-        catch let error as YumemiWeatherError {
-            XCTAssertEqual(error, YumemiWeatherError.unknownError)
-        }
-        catch {
-            XCTFail()
-        }
+        let responseJSON = try YumemiWeather.fetchWeatherList(parameter)
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
+        let decoder = JSONDecoder()
+        decoder.keyDecodingStrategy = .convertFromSnakeCase
+        decoder.dateDecodingStrategy = .formatted(dateFormatter)
+        let response = try decoder.decode([AreaResponse].self, from: Data(responseJSON.utf8))
+        XCTAssertEqual(response.count, 1)
+        let tokyo = response.first
+        XCTAssertEqual(tokyo?.area, .Tokyo)
+        
+        let responseJSON2 = try YumemiWeather.fetchWeatherList(parameter)
+        let response2 = try decoder.decode([AreaResponse].self, from: Data(responseJSON2.utf8))
+        let tokyo2 = response2.first
+        XCTAssertEqual(tokyo?.info, tokyo2?.info)
     }
 
-    func test_fetchWeatherList_jsonString_two() {
+    func test_fetchWeatherList_jsonString_two() throws {
         let parameter = """
 {
     "areas": ["Tokyo", "Nagoya"],
     "date": "2020-04-01T12:00:00+09:00"
 }
 """
-        do {
-            let responseJSON = try YumemiWeather.fetchWeatherList(parameter)
-            let dateFormatter = DateFormatter()
-            dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
-            let decoder = JSONDecoder()
-            decoder.keyDecodingStrategy = .convertFromSnakeCase
-            decoder.dateDecodingStrategy = .formatted(dateFormatter)
-            let response = try decoder.decode([AreaResponse].self, from: Data(responseJSON.utf8))
-            XCTAssertEqual(response.count, 2)
-            let tokyo = response.first(where: { $0.area == .Tokyo })
-            XCTAssertNotNil(tokyo)
-            let nagoya = response.first(where: { $0.area == .Nagoya })
-            XCTAssertNotNil(nagoya)
-            XCTAssertNotEqual(tokyo?.info, nagoya?.info)
-        }
-        catch let error as YumemiWeatherError {
-            XCTAssertEqual(error, YumemiWeatherError.unknownError)
-        }
-        catch {
-            XCTFail()
-        }
+        let responseJSON = try YumemiWeather.fetchWeatherList(parameter)
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
+        let decoder = JSONDecoder()
+        decoder.keyDecodingStrategy = .convertFromSnakeCase
+        decoder.dateDecodingStrategy = .formatted(dateFormatter)
+        let response = try decoder.decode([AreaResponse].self, from: Data(responseJSON.utf8))
+        XCTAssertEqual(response.count, 2)
+        let tokyo = response.first(where: { $0.area == .Tokyo })
+        XCTAssertNotNil(tokyo)
+        let nagoya = response.first(where: { $0.area == .Nagoya })
+        XCTAssertNotNil(nagoya)
+        XCTAssertNotEqual(tokyo?.info, nagoya?.info)
     }
 
-    func test_fetchWeatherList_jsonString_none() {
+    func test_fetchWeatherList_jsonString_none() throws {
         let parameter = """
 {
     "areas": ["LosAngeles"],
     "date": "2020-04-01T12:00:00+09:00"
 }
 """
-        do {
-            let responseJSON = try YumemiWeather.fetchWeatherList(parameter)
-            let dateFormatter = DateFormatter()
-            dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
-            let decoder = JSONDecoder()
-            decoder.keyDecodingStrategy = .convertFromSnakeCase
-            decoder.dateDecodingStrategy = .formatted(dateFormatter)
-            let response = try decoder.decode([AreaResponse].self, from: Data(responseJSON.utf8))
-            XCTAssertEqual(response.count, 0)
-        }
-        catch let error as YumemiWeatherError {
-            XCTAssertEqual(error, YumemiWeatherError.unknownError)
-        }
-        catch {
-            XCTFail()
-        }
+        let responseJSON = try YumemiWeather.fetchWeatherList(parameter)
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
+        let decoder = JSONDecoder()
+        decoder.keyDecodingStrategy = .convertFromSnakeCase
+        decoder.dateDecodingStrategy = .formatted(dateFormatter)
+        let response = try decoder.decode([AreaResponse].self, from: Data(responseJSON.utf8))
+        XCTAssertEqual(response.count, 0)
     }
 }
diff --git a/Tests/YumemiWeatherTests/YumemiWeatherTests.swift b/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
index eab6d6f..c15a480 100644
--- a/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
+++ b/Tests/YumemiWeatherTests/YumemiWeatherTests.swift
@@ -3,6 +3,10 @@ import XCTest
 
 final class YumemiWeatherTests: XCTestCase {
 
+    override func setUpWithError() throws {
+        YumemiWeather.apiQuality = .neverFails
+    }
+
     func test_ランダムにレスポンスを生成する() {
 
         // 日付を省略すると実行した瞬間のものが得られてしまうため、
@@ -49,44 +53,28 @@ final class YumemiWeatherTests: XCTestCase {
         XCTAssertNotNil(WeatherCondition(rawValue: str))
     }
 
-    func test_fetchWeather_at() {
-        do {
-            let str = try YumemiWeather.fetchWeatherCondition(at: "tokyo")
-            XCTAssertNotNil(WeatherCondition(rawValue: str))
-        }
-        catch let error as YumemiWeatherError {
-            XCTAssertEqual(error, YumemiWeatherError.unknownError)
-        }
-        catch {
-            XCTFail()
-        }
+    func test_fetchWeather_at() throws {
+        let str = try YumemiWeather.fetchWeatherCondition(at: "tokyo")
+        XCTAssertNotNil(WeatherCondition(rawValue: str))
     }
 
-    func test_fetchWeather_jsonString() {
+    func test_fetchWeather_jsonString() throws {
         let parameter = """
 {
     "area": "tokyo",
     "date": "2020-04-01T12:00:00+09:00"
 }
 """
-        do {
-            let responseJSON = try YumemiWeather.fetchWeather(parameter)
-            let dateFormatter = DateFormatter()
-            dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
-            let decoder = JSONDecoder()
-            decoder.keyDecodingStrategy = .convertFromSnakeCase
-            decoder.dateDecodingStrategy = .formatted(dateFormatter)
-            _ = try decoder.decode(Response.self, from: Data(responseJSON.utf8))
-        }
-        catch let error as YumemiWeatherError {
-            XCTAssertEqual(error, YumemiWeatherError.unknownError)
-        }
-        catch {
-            XCTFail()
-        }
+        let responseJSON = try YumemiWeather.fetchWeather(parameter)
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
+        let decoder = JSONDecoder()
+        decoder.keyDecodingStrategy = .convertFromSnakeCase
+        decoder.dateDecodingStrategy = .formatted(dateFormatter)
+        _ = try decoder.decode(Response.self, from: Data(responseJSON.utf8))
     }
 
-    func test_fetchWeather_jsonString_sync() {
+    func test_fetchWeather_jsonString_sync() throws {
         let beginDate = Date()
         let parameter = """
 {
@@ -94,21 +82,13 @@ final class YumemiWeatherTests: XCTestCase {
     "date": "2020-04-01T12:00:00+09:00"
 }
 """
-        do {
-            let responseJSON = try YumemiWeather.syncFetchWeather(parameter)
-            let dateFormatter = DateFormatter()
-            dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
-            let decoder = JSONDecoder()
-            decoder.keyDecodingStrategy = .convertFromSnakeCase
-            decoder.dateDecodingStrategy = .formatted(dateFormatter)
-            _ = try decoder.decode(Response.self, from: Data(responseJSON.utf8))
-        }
-        catch let error as YumemiWeatherError {
-            XCTAssertEqual(error, YumemiWeatherError.unknownError)
-        }
-        catch {
-            XCTFail()
-        }
+        let responseJSON = try YumemiWeather.syncFetchWeather(parameter)
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
+        let decoder = JSONDecoder()
+        decoder.keyDecodingStrategy = .convertFromSnakeCase
+        decoder.dateDecodingStrategy = .formatted(dateFormatter)
+        _ = try decoder.decode(Response.self, from: Data(responseJSON.utf8))
 
         XCTAssertGreaterThanOrEqual(Date().timeIntervalSince(beginDate), YumemiWeather.apiDuration)
     }
@@ -139,7 +119,7 @@ final class YumemiWeatherTests: XCTestCase {
     }
 
     @available(iOS 13, macOS 10.15, *)
-    func test_fetchWeather_jsonString_async() async {
+    func test_fetchWeather_jsonString_async() async throws {
         let beginDate = Date()
         let parameter = """
 {
@@ -147,21 +127,13 @@ final class YumemiWeatherTests: XCTestCase {
     "date": "2020-04-01T12:00:00+09:00"
 }
 """
-        do {
-            let responseJSON = try await YumemiWeather.asyncFetchWeather(parameter)
-            let dateFormatter = DateFormatter()
-            dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
-            let decoder = JSONDecoder()
-            decoder.keyDecodingStrategy = .convertFromSnakeCase
-            decoder.dateDecodingStrategy = .formatted(dateFormatter)
-            _ = try decoder.decode(Response.self, from: Data(responseJSON.utf8))
-        }
-        catch let error as YumemiWeatherError {
-            XCTAssertEqual(error, YumemiWeatherError.unknownError)
-        }
-        catch {
-            XCTFail()
-        }
+        let responseJSON = try await YumemiWeather.asyncFetchWeather(parameter)
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
+        let decoder = JSONDecoder()
+        decoder.keyDecodingStrategy = .convertFromSnakeCase
+        decoder.dateDecodingStrategy = .formatted(dateFormatter)
+        _ = try decoder.decode(Response.self, from: Data(responseJSON.utf8))
 
         XCTAssertGreaterThanOrEqual(Date().timeIntervalSince(beginDate), YumemiWeather.apiDuration)
     }