Merge pull request #191 from DanCardin/dc/default-none-format

fix: Default formatting when value is None/Empty and formatter is supplied.

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## 0.26
 
+### 0.26.1
+
+- fix: Default formatting when value is None/Empty and formatter is supplied.
+
 ### 0.26.0
 
 - feat: Add `Default` object with associated fallback semantics for sequences of default handlers.

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "cappa"
-version = "0.26.0"
+version = "0.26.1"
 description = "Declarative CLI argument parser."
 
 urls = {repository = "https://github.com/dancardin/cappa"}

src/cappa/default.py

@@ -222,11 +222,18 @@ def from_unknown(cls, value: str | bool | Self) -> Self:
         return cls(show=bool(value))
 
     def format_default(self, default: Default, default_format: str = "") -> str:
-        if not self.show or default.default in (None, Empty):
+        if not self.show:
             return ""
 
-        default_value = self.format.format(default=default.default)
-        return default_format.format(default=default_value)
+        default_raw_value = default.default
+        if default_raw_value in (None, Empty):
+            default_raw_value = ""
+
+        default_formatted_value = self.format.format(default=default_raw_value)
+        if default_formatted_value == "":
+            return default_formatted_value
+
+        return default_format.format(default=default_formatted_value)
 
 
 PromptType = rich.prompt.Prompt

tests/arg/test_show_default.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import re
 from dataclasses import dataclass
 
 import pytest
@@ -98,3 +99,16 @@ class Command:
 
     stdout = CapsysOutput.from_capsys(capsys).stdout.replace(" ", "")
     assert "[FOO](Default:!asdf!)" in stdout
+
+
+@backends
+def test_static(backend, capsys):
+    @dataclass
+    class Command:
+        foo: Annotated[str | None, cappa.Arg(show_default="always show")] = None
+
+    with pytest.raises(cappa.HelpExit):
+        parse(Command, "--help", backend=backend)
+
+    stdout = CapsysOutput.from_capsys(capsys).stdout
+    assert re.search(r"\[FOO\]\s+\(Default: always show\)", stdout)