Add unit tests for DefaultHomeRemoteDataSource

Author: MihaiCristianCondrea

app/src/test/java/com/d4rk/androidtutorials/java/data/source/DefaultHomeRemoteDataSourceTest.java

@@ -0,0 +1,116 @@
+package com.d4rk.androidtutorials.java.data.source;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.os.Handler;
+
+import com.android.volley.RequestQueue;
+import com.android.volley.VolleyError;
+import com.android.volley.toolbox.JsonObjectRequest;
+import com.d4rk.androidtutorials.java.data.model.PromotedApp;
+
+import org.json.JSONArray;
+import org.json.JSONObject;
+import org.junit.Test;
+import org.mockito.ArgumentCaptor;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.Executor;
+
+public class DefaultHomeRemoteDataSourceTest {
+
+    @Test
+    @SuppressWarnings("unchecked")
+    public void fetchPromotedApps_filtersInternalPackages() throws Exception {
+        RequestQueue requestQueue = mock(RequestQueue.class);
+        DefaultHomeRemoteDataSource dataSource = new DefaultHomeRemoteDataSource(requestQueue, "https://example.com");
+        makeSynchronous(dataSource);
+        HomeRemoteDataSource.PromotedAppsCallback callback = mock(HomeRemoteDataSource.PromotedAppsCallback.class);
+
+        dataSource.fetchPromotedApps(callback);
+
+        ArgumentCaptor<JsonObjectRequest> requestCaptor = ArgumentCaptor.forClass(JsonObjectRequest.class);
+        verify(requestQueue).add(requestCaptor.capture());
+        JsonObjectRequest capturedRequest = requestCaptor.getValue();
+
+        JSONObject response = new JSONObject()
+                .put("data", new JSONObject()
+                        .put("apps", new JSONArray()
+                                .put(new JSONObject()
+                                        .put("name", "Android Tutorials")
+                                        .put("packageName", "com.d4rk.androidtutorials.sample")
+                                        .put("iconLogo", "internal.png"))
+                                .put(new JSONObject()
+                                        .put("name", "Cool App")
+                                        .put("packageName", "com.example.cool")
+                                        .put("iconLogo", "cool.png"))
+                                .put(new JSONObject()
+                                        .put("name", "Another App")
+                                        .put("packageName", "org.sample.another")
+                                        .put("iconLogo", "another.png"))));
+
+        invokeDeliverResponse(capturedRequest, response);
+
+        ArgumentCaptor<List> appsCaptor = ArgumentCaptor.forClass(List.class);
+        verify(callback).onResult(appsCaptor.capture());
+        List<PromotedApp> apps = appsCaptor.getValue();
+        List<PromotedApp> expected = Arrays.asList(
+                new PromotedApp("Cool App", "com.example.cool", "cool.png"),
+                new PromotedApp("Another App", "org.sample.another", "another.png"));
+        assertEquals(expected, apps);
+    }
+
+    @Test
+    @SuppressWarnings("unchecked")
+    public void fetchPromotedApps_errorReturnsEmptyList() throws Exception {
+        RequestQueue requestQueue = mock(RequestQueue.class);
+        DefaultHomeRemoteDataSource dataSource = new DefaultHomeRemoteDataSource(requestQueue, "https://example.com");
+        makeSynchronous(dataSource);
+        HomeRemoteDataSource.PromotedAppsCallback callback = mock(HomeRemoteDataSource.PromotedAppsCallback.class);
+
+        dataSource.fetchPromotedApps(callback);
+
+        ArgumentCaptor<JsonObjectRequest> requestCaptor = ArgumentCaptor.forClass(JsonObjectRequest.class);
+        verify(requestQueue).add(requestCaptor.capture());
+        JsonObjectRequest capturedRequest = requestCaptor.getValue();
+
+        capturedRequest.deliverError(new VolleyError("network"));
+
+        ArgumentCaptor<List> appsCaptor = ArgumentCaptor.forClass(List.class);
+        verify(callback).onResult(appsCaptor.capture());
+        List<PromotedApp> apps = appsCaptor.getValue();
+        assertTrue(apps.isEmpty());
+    }
+
+    private static void makeSynchronous(DefaultHomeRemoteDataSource dataSource) throws Exception {
+        Handler handler = mock(Handler.class);
+        when(handler.post(any())).thenAnswer(invocation -> {
+            Runnable runnable = invocation.getArgument(0);
+            runnable.run();
+            return true;
+        });
+
+        setField(dataSource, "executor", (Executor) Runnable::run);
+        setField(dataSource, "mainHandler", handler);
+    }
+
+    private static void setField(DefaultHomeRemoteDataSource dataSource, String name, Object value) throws Exception {
+        Field field = DefaultHomeRemoteDataSource.class.getDeclaredField(name);
+        field.setAccessible(true);
+        field.set(dataSource, value);
+    }
+
+    private static void invokeDeliverResponse(JsonObjectRequest request, JSONObject response) throws Exception {
+        Method deliverResponse = JsonObjectRequest.class.getDeclaredMethod("deliverResponse", JSONObject.class);
+        deliverResponse.setAccessible(true);
+        deliverResponse.invoke(request, response);
+    }
+}