Re-read the event detail when the same occurrence is reopened (#196)

app/src/main/java/de/jeanlucmakiola/calendula/ui/detail/EventDetailViewModel.kt

@@ -78,9 +78,15 @@ class EventDetailViewModel @Inject constructor(
      * the occurrence's own times (from `CalendarContract.Instances`); they
      * override the series DTSTART/DTEND so recurring events show the correct
      * date instead of the first occurrence.
+     *
+     * Re-opening the *same* occurrence always re-reads it. The view model
+     * outlives the sheet, and a `StateFlow` conflates an identical value away,
+     * so assigning the target alone would leave an edit that changed no time —
+     * adding a description, say (#196) — showing the state from before the save.
      */
     fun open(eventId: Long, beginMillis: Long, endMillis: Long) {
-        _target.value = Target(eventId, beginMillis, endMillis)
+        val target = Target(eventId, beginMillis, endMillis)
+        if (_target.value == target) _reload.value += 1 else _target.value = target
     }
 
     /** Re-run the current load after a failure. */

app/src/test/java/de/jeanlucmakiola/calendula/ui/detail/EventDetailViewModelTest.kt

@@ -0,0 +1,103 @@
+package de.jeanlucmakiola.calendula.ui.detail
+
+import android.content.ContextWrapper
+import androidx.datastore.preferences.core.PreferenceDataStoreFactory
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.calendula.data.calendar.CalendarRepositoryImpl
+import de.jeanlucmakiola.calendula.data.calendar.FakeCalendarDataSource
+import de.jeanlucmakiola.calendula.data.ics.IcsExporter
+import de.jeanlucmakiola.calendula.data.prefs.CalendarPrefs
+import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
+import de.jeanlucmakiola.calendula.domain.CalendarSource
+import de.jeanlucmakiola.calendula.domain.EventDetail
+import de.jeanlucmakiola.calendula.domain.EventInstance
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import kotlinx.coroutines.test.advanceUntilIdle
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.runTest
+import kotlinx.coroutines.test.setMain
+import org.junit.jupiter.api.AfterEach
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.io.TempDir
+import java.nio.file.Path
+import kotlin.time.Instant
+
+/**
+ * Re-opening an occurrence must re-read it (#196): the view model outlives the
+ * sheet, so an edit that changed no time would otherwise show the pre-save row.
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+class EventDetailViewModelTest {
+
+    private val dispatcher = UnconfinedTestDispatcher()
+
+    @BeforeEach fun setUp() = Dispatchers.setMain(dispatcher)
+    @AfterEach fun tearDown() = Dispatchers.resetMain()
+
+    private val beginMillis = 1_781_164_800_000L
+    private val endMillis = beginMillis + 3_600_000L
+
+    private fun detail(description: String?) = EventDetail(
+        instance = EventInstance(
+            instanceId = 42L, eventId = 42L, calendarId = 1L, title = "Standup",
+            start = Instant.fromEpochMilliseconds(beginMillis),
+            end = Instant.fromEpochMilliseconds(endMillis),
+            isAllDay = false, color = 0xFF000000.toInt(), location = null,
+        ),
+        description = description, organizer = null, attendees = emptyList(), rrule = null,
+    )
+
+    private fun viewModel(tempDir: Path, fake: FakeCalendarDataSource): EventDetailViewModel {
+        val prefs = CalendarPrefs(
+            PreferenceDataStoreFactory.create(
+                scope = CoroutineScope(dispatcher),
+                produceFile = { tempDir.resolve("detail_prefs.preferences_pb").toFile() },
+            ),
+        )
+        val settings = SettingsPrefs(
+            PreferenceDataStoreFactory.create(
+                scope = CoroutineScope(dispatcher),
+                produceFile = { tempDir.resolve("detail_settings.preferences_pb").toFile() },
+            ),
+        )
+        val repo = CalendarRepositoryImpl(fake, prefs, settings, dispatcher as CoroutineDispatcher)
+        // Only `shareUri()` touches the exporter, and nothing here shares.
+        return EventDetailViewModel(repo, IcsExporter(ContextWrapper(null)), dispatcher)
+    }
+
+    @Test
+    fun `re-opening the same occurrence re-reads it`(@TempDir tempDir: Path) = runTest(dispatcher) {
+        var stored: String? = null
+        val fake = FakeCalendarDataSource().apply {
+            calendarsResult = listOf(
+                CalendarSource(
+                    id = 1L, displayName = "Cal", accountName = "acc@local", accountType = "LOCAL",
+                    color = 0xFF112233.toInt(), isVisibleInSystem = true, canModifyContents = true,
+                ),
+            )
+            eventDetailResult = { detail(stored) }
+        }
+        val vm = viewModel(tempDir, fake)
+        val collector = launch(Job()) { vm.state.collect {} }
+
+        vm.open(42L, beginMillis, endMillis)
+        advanceUntilIdle()
+        assertThat((vm.state.value as EventDetailUiState.Success).detail.description).isNull()
+
+        // The edit screen saved a description; the tapped occurrence is unchanged.
+        stored = "Bring the roadmap"
+        vm.open(42L, beginMillis, endMillis)
+        advanceUntilIdle()
+        assertThat((vm.state.value as EventDetailUiState.Success).detail.description)
+            .isEqualTo("Bring the roadmap")
+
+        collector.cancel()
+    }
+}