android - 使用 Robolectric : Width and height are always 0 测试自定义 View

Question

我已经为绘图应用构建了一个自定义 View (DrawView)。它在很大程度上取决于内部位图的实际宽度和高度。当我尝试使用 Robolectric 2.2 对其进行测试时， View 的长度和宽度均为 0，这使我的内部逻辑崩溃。我怎样才能模拟真实的屏幕尺寸？我使用一个简单的 LinearLayout 和 DrawView 作为其中唯一要测试的元素。这是我的布局:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/drawViewLayout">
    <net.thoster.scribmasterlib.DrawView
        android:id="@+id/drawView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        />
</LinearLayout>

这是我的单元测试:

@RunWith(RobolectricTestRunner.class)
public class DrawViewTest {
  Activity activity;
  DrawView drawView;
  LinearLayout layout;

  @Before
  public void setUp() throws Exception {

    ActivityController<Activity> activityController = Robolectric.buildActivity(Activity.class).create().start().resume()
        .visible();

    Activity activity = activityController.get();

    layout = (LinearLayout) LayoutInflater.from(activity).inflate(R.layout.test, null);
    drawView = (DrawView) layout.findViewById(R.id.drawView);

  }

  @Test
  public void testFloodFill() throws Exception {
    System.out.println(drawView.getWidth());
    drawView.floodFill(new Point(1, 1), Color.BLACK, FloodFillMode.PIXEL);
    Bitmap b = drawView.getDrawingAsNewBitmap();
    int pixel = b.getPixel(2, 2);
    assertEquals(pixel, Color.BLACK);

  }

}

Answer 1

正如 erd 在 https://github.com/robolectric/robolectric/issues/819 中指出的那样...

Robolectric isn't trying to emulate Android - just fake enough of it so you can write reasonable unit tests. It doesn't surprise me that views don't have a width or height, since we're not doing anything that would cause a layout pass to happen.

请查看潜在变通方法的错误。