Add memory leak detection tests

sample/src/androidTest/java/com/sebaslogen/resacaapp/sample/MemoryLeakTests.kt

@@ -0,0 +1,67 @@
+package com.sebaslogen.resacaapp.sample
+
+import android.content.Intent
+import androidx.compose.ui.test.junit4.createEmptyComposeRule
+import androidx.compose.ui.test.onNodeWithTag
+import androidx.compose.ui.test.performClick
+import androidx.test.core.app.ActivityScenario
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.sebaslogen.resacaapp.sample.ui.main.ComposeActivity
+import com.sebaslogen.resacaapp.sample.ui.main.rememberScopedDestination
+import com.sebaslogen.resacaapp.sample.utils.ComposeTestUtils
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.lang.ref.WeakReference
+import kotlin.test.assertNotNull
+import kotlin.test.assertNull
+
+@RunWith(AndroidJUnit4::class)
+class MemoryLeakTests : ComposeTestUtils {
+
+    private lateinit var scenario: ActivityScenario<ComposeActivity>
+
+    @get:Rule
+    override val composeTestRule = createEmptyComposeRule()
+
+    @Before
+    fun setUp() {
+        scenario = ActivityScenario.launch(
+            Intent(ApplicationProvider.getApplicationContext(), ComposeActivity::class.java).apply {
+                putExtra(ComposeActivity.START_DESTINATION, rememberScopedDestination)
+            })
+    }
+
+    @Test
+    fun givenComposeActivityWithComposablesInANestedNavigationComposable_whenTheActivityIsRecreated_thenTheOriginalComposeActivityObjectIsGarbageCollected() {
+        var weakActivityReference: WeakReference<ComposeActivity>? = null
+        // Given I create the Activity
+        composeTestRule.waitForIdle()
+        scenario.onActivity { activity: ComposeActivity ->
+
+            // And we grab a WeakReference to the Activity
+            weakActivityReference = WeakReference(activity)
+        }
+        printComposeUiTreeToLog()
+
+        // And I click "Navigate to rememberScoped" to get to a nested screen in the same Activity
+        composeTestRule.waitForIdle()
+        composeTestRule.onNodeWithTag("Navigate to rememberScoped").performClick()
+        printComposeUiTreeToLog()
+        composeTestRule.waitForIdle()
+
+        // When we recreate the activity
+        scenario.recreate()
+        composeTestRule.waitForIdle()
+
+        // And trigger Garbage Collection to make sure old ComposeActivity is collected
+        Runtime.getRuntime().gc()
+        printComposeUiTreeToLog()
+
+        // Then the original Activity object is garbage collected
+        assertNotNull(weakActivityReference) { "WeakReference container for initial ComposeActivity should not be null because it was created" }
+        assertNull(weakActivityReference?.get(), "Initial ComposeActivity should have been garbage collected but it wasn't, so it's leaking")
+    }
+}

sample/src/main/java/com/sebaslogen/resacaapp/sample/ui/main/ComposeActivity.kt

@@ -19,6 +19,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.platform.testTag
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.navigation.NavHostController
@@ -122,7 +123,7 @@ fun ScreensWithNavigation(navController: NavHostController = rememberNavControll
  */
 @Composable
 fun NavigationButtons(navController: NavHostController) {
-    Button(modifier = Modifier.padding(top = 16.dp, bottom = 2.dp),
+    Button(modifier = Modifier.padding(top = 16.dp, bottom = 2.dp).testTag("Navigate to rememberScoped"),
         onClick = { navController.navigate(rememberScopedDestination) }) {
         Text(text = "Push rememberScoped destination")
     }

sample/src/test/java/com/sebaslogen/resacaapp/sample/MemoryLeakTests.kt

@@ -0,0 +1,62 @@
+package com.sebaslogen.resacaapp.sample
+
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.test.performClick
+import androidx.test.core.app.ActivityScenario
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.sebaslogen.resacaapp.sample.ui.main.ComposeActivity
+import com.sebaslogen.resacaapp.sample.ui.main.rememberScopedDestination
+import com.sebaslogen.resacaapp.sample.utils.ComposeTestUtils
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.lang.ref.WeakReference
+import kotlin.test.assertNotNull
+import kotlin.test.assertNull
+
+@RunWith(AndroidJUnit4::class)
+class MemoryLeakTests : ComposeTestUtils {
+    init {
+        callFromTestInit()
+    }
+
+    override fun callFromTestInit() {
+        ComposeActivity.defaultDestination = rememberScopedDestination // This is needed to reset the destination to the default one on the release app
+    }
+
+    @get:Rule
+    override val composeTestRule = createComposeRule()
+
+    @Test
+    fun `given ComposeActivity with Composables in a nested Navigation Composable, when the activity is recreated, then the original ComposeActivity object is garbage collected`() {
+        ActivityScenario.launch(ComposeActivity::class.java).use { scenario ->
+            var weakActivityReference: WeakReference<ComposeActivity>? = null
+            // Given I create the Activity and navigate to a nested screen
+            scenario.onActivity { activity: ComposeActivity ->
+
+                // Given the Activity shows a screen with scoped objects
+                printComposeUiTreeToLog()
+
+                // And I grab a WeakReference to the Activity
+                weakActivityReference = WeakReference(activity)
+
+                // And I click "Navigate to rememberScoped" to get to a nested screen in the same Activity
+                onNodeWithTestTag("Navigate to rememberScoped").performClick()
+                printComposeUiTreeToLog()
+            }
+
+            // When we recreate the activity
+            scenario.recreate().onActivity {
+
+                // And trigger Garbage Collection to make sure old ComposeActivity is collected
+                System.gc()
+                printComposeUiTreeToLog()
+
+                // Then the original Activity object is garbage collected
+                assertNotNull(weakActivityReference) { "WeakReference container for initial ComposeActivity should not be null because it was created" }
+                assertNull(weakActivityReference?.get(), "Initial ComposeActivity should have been garbage collected but it wasn't, so it's leaking")
+            }
+
+        }
+    }
+}

sample/src/test/java/com/sebaslogen/resacaapp/sample/ScopeKeysTest.kt

@@ -23,7 +23,6 @@ import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 
-@OptIn(ExperimentalCoroutinesApi::class)
 @RunWith(AndroidJUnit4::class)
 class ScopeKeysTest : ComposeTestUtils {
     init {