Add some tests

app/src/test/kotlin/app/hypostats/ui/MainViewModelTest.kt

@@ -0,0 +1,52 @@
+package app.hypostats.ui
+
+import app.hypostats.ui.model.AppTab
+import app.hypostats.ui.model.DrawerDestination
+import app.hypostats.util.FakeSettingsRepository
+import app.hypostats.util.MainDispatcherRule
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Rule
+import org.junit.Test
+
+@OptIn(ExperimentalCoroutinesApi::class)
+class MainViewModelTest {
+    @get:Rule
+    val mainDispatcherRule = MainDispatcherRule(UnconfinedTestDispatcher())
+
+    private fun TestScope.collectState(viewModel: MainViewModel) {
+        backgroundScope.launch(UnconfinedTestDispatcher(testScheduler)) {
+            viewModel.state.collect {}
+        }
+    }
+
+    @Test
+    fun `selectTab updates selected tab`() =
+        runTest {
+            val viewModel = MainViewModel(FakeSettingsRepository())
+            collectState(viewModel)
+
+            assertEquals(AppTab.HYPO, viewModel.state.value.selectedTab)
+
+            viewModel.selectTab(AppTab.STATS)
+
+            assertEquals(AppTab.STATS, viewModel.state.value.selectedTab)
+        }
+
+    @Test
+    fun `selectDrawerDestination updates selected drawer destination`() =
+        runTest {
+            val viewModel = MainViewModel(FakeSettingsRepository())
+            collectState(viewModel)
+
+            assertEquals(DrawerDestination.HOME, viewModel.state.value.selectedDrawerDestination)
+
+            viewModel.selectDrawerDestination(DrawerDestination.ABOUT)
+
+            assertEquals(DrawerDestination.ABOUT, viewModel.state.value.selectedDrawerDestination)
+        }
+}

app/src/test/kotlin/app/hypostats/ui/log/LogViewModelTest.kt

@@ -0,0 +1,37 @@
+package app.hypostats.ui.log
+
+import app.hypostats.domain.model.Treatment
+import app.hypostats.util.FakeTreatmentRepository
+import app.hypostats.util.MainDispatcherRule
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.test.TestScope
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Rule
+import org.junit.Test
+import java.time.Instant
+
+@OptIn(ExperimentalCoroutinesApi::class)
+class LogViewModelTest {
+    @get:Rule
+    val mainDispatcherRule = MainDispatcherRule(UnconfinedTestDispatcher())
+
+    private fun TestScope.collectTreatments(viewModel: LogViewModel) {
+        backgroundScope.launch(UnconfinedTestDispatcher(testScheduler)) {
+            viewModel.treatments.collect {}
+        }
+    }
+
+    @Test
+    fun `treatments are sorted newest first`() =
+        runTest {
+            val older = Treatment(Instant.parse("2024-01-01T00:00:00Z"), 10)
+            val newer = Treatment(Instant.parse("2024-01-02T00:00:00Z"), 10)
+            val viewModel = LogViewModel(FakeTreatmentRepository(listOf(older, newer)))
+            collectTreatments(viewModel)
+
+            assertEquals(listOf(newer, older), viewModel.treatments.value)
+        }
+}

app/src/test/kotlin/app/hypostats/util/FakeTreatmentRepository.kt

@@ -7,8 +7,10 @@ import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import java.time.Instant
 
-class FakeTreatmentRepository : TreatmentRepository {
-    private val treatmentsFlow = MutableStateFlow<List<Treatment>>(emptyList())
+class FakeTreatmentRepository(
+    initialTreatments: List<Treatment> = emptyList(),
+) : TreatmentRepository {
+    private val treatmentsFlow = MutableStateFlow<List<Treatment>>(initialTreatments)
     private val trackingStartDateFlow = MutableStateFlow(Instant.EPOCH)
 
     override fun getAllTreatments(): Flow<List<Treatment>> = treatmentsFlow.asStateFlow()

app/src/test/kotlin/app/hypostats/util/MainDispatcherRule.kt

@@ -0,0 +1,23 @@
+@file:OptIn(kotlinx.coroutines.ExperimentalCoroutinesApi::class)
+
+package app.hypostats.util
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.TestDispatcher
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.setMain
+import org.junit.rules.TestWatcher
+import org.junit.runner.Description
+
+class MainDispatcherRule(
+    val testDispatcher: TestDispatcher = StandardTestDispatcher(),
+) : TestWatcher() {
+    override fun starting(description: Description) {
+        Dispatchers.setMain(testDispatcher)
+    }
+
+    override fun finished(description: Description) {
+        Dispatchers.resetMain()
+    }
+}