Add comprehensive ViewModel unit tests

app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/android/CodeViewModel.java

@@ -8,15 +8,22 @@
 import com.d4rk.androidtutorials.java.ui.screens.android.repository.LessonRepository;
 
 public class CodeViewModel extends ViewModel {
-    private final MutableLiveData<LessonRepository.Lesson> lesson = new MutableLiveData<>();
-    private final LessonRepository repository = new LessonRepository();
-    private final GetLessonUseCase getLessonUseCase = new GetLessonUseCase(repository);
+    private final MutableLiveData<com.d4rk.androidtutorials.java.data.repository.LessonRepository.Lesson> lesson = new MutableLiveData<>();
+    private final GetLessonUseCase getLessonUseCase;
+
+    public CodeViewModel() {
+        this(new GetLessonUseCase(new LessonRepository()));
+    }
+
+    CodeViewModel(GetLessonUseCase getLessonUseCase) {
+        this.getLessonUseCase = getLessonUseCase;
+    }
 
     public void setLessonName(String lessonName) {
         lesson.setValue(getLessonUseCase.invoke(lessonName));
     }
 
-    public LiveData<LessonRepository.Lesson> getLesson() {
+    public LiveData<com.d4rk.androidtutorials.java.data.repository.LessonRepository.Lesson> getLesson() {
         return lesson;
     }
 }

app/src/test/java/com/d4rk/androidtutorials/java/ui/screens/android/CodeViewModelTest.java

@@ -0,0 +1,57 @@
+package com.d4rk.androidtutorials.java.ui.screens.android;
+
+import static org.junit.Assert.assertEquals;
+
+import androidx.arch.core.executor.testing.InstantTaskExecutorRule;
+
+import com.d4rk.androidtutorials.java.data.repository.LessonRepository;
+import com.d4rk.androidtutorials.java.domain.android.GetLessonUseCase;
+
+import org.junit.Rule;
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class CodeViewModelTest {
+
+    @Rule
+    public InstantTaskExecutorRule instantTaskExecutorRule = new InstantTaskExecutorRule();
+
+    @Test
+    public void setLessonName_updatesLiveData() {
+        FakeLessonRepository repository = new FakeLessonRepository();
+        LessonRepository.Lesson expected = new LessonRepository.Lesson(1, 2, 3);
+        repository.addLesson("lesson", expected);
+        CodeViewModel viewModel = new CodeViewModel(new GetLessonUseCase(repository));
+
+        viewModel.setLessonName("lesson");
+
+        assertEquals(expected, viewModel.getLesson().getValue());
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void setLessonName_unknownLessonThrows() {
+        FakeLessonRepository repository = new FakeLessonRepository();
+        CodeViewModel viewModel = new CodeViewModel(new GetLessonUseCase(repository));
+
+        viewModel.setLessonName("unknown");
+    }
+
+    private static final class FakeLessonRepository implements LessonRepository {
+        private final Map<String, Lesson> lessons = new HashMap<>();
+
+        void addLesson(String name, Lesson lesson) {
+            lessons.put(name, lesson);
+        }
+
+        @Override
+        public Lesson getLesson(String lessonName) {
+            Lesson lesson = lessons.get(lessonName);
+            if (lesson == null) {
+                throw new IllegalArgumentException("Unknown lesson: " + lessonName);
+            }
+            return lesson;
+        }
+    }
+}

app/src/test/java/com/d4rk/androidtutorials/java/ui/screens/help/HelpViewModelTest.java

@@ -0,0 +1,63 @@
+package com.d4rk.androidtutorials.java.ui.screens.help;
+
+import static org.junit.Assert.assertSame;
+
+import android.app.Activity;
+
+import com.d4rk.androidtutorials.java.data.repository.HelpRepository;
+import com.d4rk.androidtutorials.java.domain.help.LaunchReviewFlowUseCase;
+import com.d4rk.androidtutorials.java.domain.help.RequestReviewFlowUseCase;
+import com.google.android.play.core.review.ReviewInfo;
+
+import org.junit.Test;
+import org.mockito.Mockito;
+
+public class HelpViewModelTest {
+
+    @Test
+    public void requestReviewFlowDelegatesToRepository() {
+        FakeHelpRepository repository = new FakeHelpRepository();
+        HelpViewModel viewModel = new HelpViewModel(
+                new RequestReviewFlowUseCase(repository),
+                new LaunchReviewFlowUseCase(repository)
+        );
+        HelpRepository.OnReviewInfoListener listener = Mockito.mock(HelpRepository.OnReviewInfoListener.class);
+
+        viewModel.requestReviewFlow(listener);
+
+        assertSame(listener, repository.lastListener);
+    }
+
+    @Test
+    public void launchReviewFlowDelegatesToRepository() {
+        FakeHelpRepository repository = new FakeHelpRepository();
+        HelpViewModel viewModel = new HelpViewModel(
+                new RequestReviewFlowUseCase(repository),
+                new LaunchReviewFlowUseCase(repository)
+        );
+        Activity activity = Mockito.mock(Activity.class);
+        ReviewInfo info = Mockito.mock(ReviewInfo.class);
+
+        viewModel.launchReviewFlow(activity, info);
+
+        assertSame(activity, repository.lastActivity);
+        assertSame(info, repository.lastReviewInfo);
+    }
+
+    private static final class FakeHelpRepository implements HelpRepository {
+        private HelpRepository.OnReviewInfoListener lastListener;
+        private Activity lastActivity;
+        private ReviewInfo lastReviewInfo;
+
+        @Override
+        public void requestReviewFlow(OnReviewInfoListener listener) {
+            lastListener = listener;
+        }
+
+        @Override
+        public void launchReviewFlow(Activity activity, ReviewInfo reviewInfo) {
+            lastActivity = activity;
+            lastReviewInfo = reviewInfo;
+        }
+    }
+}

app/src/test/java/com/d4rk/androidtutorials/java/ui/screens/home/HomeViewModelTest.java

@@ -4,6 +4,9 @@
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 
+import android.content.Intent;
+import android.net.Uri;
+
 import androidx.arch.core.executor.testing.InstantTaskExecutorRule;
 
 import com.d4rk.androidtutorials.java.data.model.PromotedApp;
@@ -16,7 +19,10 @@
 import org.junit.Rule;
 import org.junit.Test;
 
+import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 
 public class HomeViewModelTest {
@@ -28,12 +34,7 @@ public class HomeViewModelTest {
     public void uiStateUpdatesWithData() {
         List<PromotedApp> promoted = List.of(new PromotedApp("App", "pkg", "icon"));
         FakeHomeRepository repo = new FakeHomeRepository(promoted);
-        HomeViewModel viewModel = new HomeViewModel(
-                new GetDailyTipUseCase(repo),
-                new GetPromotedAppsUseCase(repo),
-                new GetPlayStoreUrlUseCase(repo),
-                new GetAppPlayStoreUrlUseCase(repo)
-        );
+        HomeViewModel viewModel = createViewModel(repo);
         viewModel.setAnnouncements("Title", "Subtitle");
 
         HomeUiState state = viewModel.getUiState().getValue();
@@ -47,39 +48,118 @@ public void uiStateUpdatesWithData() {
     @Test
     public void uiStateHandlesEmptyPromotedApps() {
         FakeHomeRepository repo = new FakeHomeRepository(List.of());
-        HomeViewModel viewModel = new HomeViewModel(
-                new GetDailyTipUseCase(repo),
-                new GetPromotedAppsUseCase(repo),
-                new GetPlayStoreUrlUseCase(repo),
-                new GetAppPlayStoreUrlUseCase(repo)
-        );
+        HomeViewModel viewModel = createViewModel(repo);
         viewModel.setAnnouncements("Title", "Subtitle");
 
         HomeUiState state = viewModel.getUiState().getValue();
         assertNotNull(state);
         assertTrue(state.promotedApps().isEmpty());
     }
 
-    record FakeHomeRepository(List<PromotedApp> apps) implements HomeRepository {
+    @Test
+    public void promotedAppsLimitedToAtMostFour() {
+        List<PromotedApp> promoted = List.of(
+                new PromotedApp("App1", "pkg1", "icon1"),
+                new PromotedApp("App2", "pkg2", "icon2"),
+                new PromotedApp("App3", "pkg3", "icon3"),
+                new PromotedApp("App4", "pkg4", "icon4"),
+                new PromotedApp("App5", "pkg5", "icon5")
+        );
+        FakeHomeRepository repo = new FakeHomeRepository(promoted);
+        HomeViewModel viewModel = createViewModel(repo);
+
+        HomeUiState state = viewModel.getUiState().getValue();
+        assertNotNull(state);
+        assertTrue(state.promotedApps().size() <= 4);
+    }
+
+    @Test
+    public void getOpenPlayStoreIntent_buildsViewIntent() {
+        FakeHomeRepository repo = new FakeHomeRepository(List.of());
+        String expectedUrl = "https://play.google.com/store/apps/details?id=com.example";
+        repo.setPlayStoreUrl(expectedUrl);
+        HomeViewModel viewModel = createViewModel(repo);
+
+        Intent intent = viewModel.getOpenPlayStoreIntent();
+
+        assertEquals(Intent.ACTION_VIEW, intent.getAction());
+        assertEquals(Uri.parse(expectedUrl), intent.getData());
+    }
+
+    @Test
+    public void getPromotedAppIntent_buildsViewIntent() {
+        FakeHomeRepository repo = new FakeHomeRepository(List.of());
+        String packageName = "pkg";
+        String expectedUrl = "https://play.google.com/store/apps/details?id=" + packageName;
+        repo.setAppUrl(packageName, expectedUrl);
+        HomeViewModel viewModel = createViewModel(repo);
+
+        Intent intent = viewModel.getPromotedAppIntent(packageName);
+
+        assertEquals(Intent.ACTION_VIEW, intent.getAction());
+        assertEquals(Uri.parse(expectedUrl), intent.getData());
+    }
+
+    @Test
+    public void getLearnMoreIntent_targetsAndroidDevelopers() {
+        FakeHomeRepository repo = new FakeHomeRepository(List.of());
+        HomeViewModel viewModel = createViewModel(repo);
+
+        Intent intent = viewModel.getLearnMoreIntent();
+
+        assertEquals(Intent.ACTION_VIEW, intent.getAction());
+        assertEquals(Uri.parse("https://developer.android.com"), intent.getData());
+    }
+
+    private HomeViewModel createViewModel(FakeHomeRepository repo) {
+        return new HomeViewModel(
+                new GetDailyTipUseCase(repo),
+                new GetPromotedAppsUseCase(repo),
+                new GetPlayStoreUrlUseCase(repo),
+                new GetAppPlayStoreUrlUseCase(repo)
+        );
+    }
+
+    private static final class FakeHomeRepository implements HomeRepository {
+        private final List<PromotedApp> promotedApps;
+        private String dailyTip = "tip";
+        private String playStoreUrl = "https://play.google.com/store/apps/details?id=default";
+        private final Map<String, String> appUrls = new HashMap<>();
+
+        FakeHomeRepository(List<PromotedApp> promotedApps) {
+            this.promotedApps = new ArrayList<>(promotedApps);
+        }
+
+        void setDailyTip(String dailyTip) {
+            this.dailyTip = dailyTip;
+        }
+
+        void setPlayStoreUrl(String playStoreUrl) {
+            this.playStoreUrl = playStoreUrl;
+        }
+
+        void setAppUrl(String packageName, String url) {
+            appUrls.put(packageName, url);
+        }
 
         @Override
         public String dailyTip() {
-            return "tip";
+            return dailyTip;
         }
 
         @Override
         public String getPlayStoreUrl() {
-            return "";
+            return playStoreUrl;
         }
 
         @Override
         public String getAppPlayStoreUrl(String packageName) {
-            return "";
+            return appUrls.getOrDefault(packageName, "");
         }
 
         @Override
         public void fetchPromotedApps(PromotedAppsCallback callback) {
-            callback.onResult(apps);
+            callback.onResult(promotedApps);
         }
     }
 }