junit - 在 Robolectric 中测试时片段 getView 返回 null

Question

1.我想使用 robolectric 框架测试片段。我正在使用 android-support-v4.jar 。未调用 NewFragment 类的 onCreateView() 方法。

============================================= ============

@RunWith(RobolectricTestRunner.class)
public class NewFragmentTest extends Fragment{
private NewFragment newFragment;


public void startFragment(Fragment fragment) {

            FragmentActivity  activity=Robolectric.buildActivity(FragmentActivity.class).create().start().resume().get();
     FragmentManager fragmentManager = activity
     .getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager
            .beginTransaction();

     fragmentTransaction.replace(R.id.content_frame,fragment,
     "new fragment");

    //fragmentTransaction.add(fragment, "");
    // fragmentTransaction.commit();
}

@Before
public void setUp() throws Exception {
    newFragment = new NewFragment();
    newFragment.onCreate(null);
    startFragment(newFragment);
}

@Test
public void testFragmentNotNull() {
    Assert.assertNotNull(newFragment);
}

@Test
public void shouldHaveButton() throws Exception {
    TextView textview = (TextView) getView().findViewById(R.id.id_txt);

    assertThat(textview.getVisibility(), equalTo(View.VISIBLE));

}

   When i am running tests its giving below exception.


    java.lang.NullPointerException
at com.askcs.robodemo.NewFragmentTest.shouldHaveButton(NewFragmentTest.java:62)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
atorg.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.ja44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.robolectric.RobolectricTestRunner$2.evaluate(RobolectricTestRunner.java:236)
at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
at org.junit.runners.ParentRunner.access$000(Parent`enter code here`Runner.java:42)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
at org.robolectric.RobolectricTestRunner$1.evaluate(RobolectricTestRunner.java:177)
at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

Answer 1

您的 getView() 返回 null，因为片段尚未添加。查看来自 Robolectric 的代码 FragmentTestUtil .

startFragment() 方法如下所示:

  public static void startFragment(Fragment fragment) {
    buildFragmentManager(FragmentUtilActivity.class)
        .beginTransaction().add(fragment, null).commit();
  }

内部类 FragmentUtilActivity 看起来像这样:

  private static class FragmentUtilActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      LinearLayout view = new LinearLayout(this);
      view.setId(1);

      setContentView(view);
    }
  }

这就是问题所在。开发人员给出布局，ID 1。add(Fragment, String) - 来自 FragmentTransaction 的方法说:

Calls add(int, Fragment, String) with a 0 containerViewId.

因此，放置在 startFragment(Fragment) 中的 Fragment 被放置在 ID 0 中。它不存在。

解决方案:

调用方法startVisibleFragment(Fragment)。代码看起来与 startFramgent(Fragment) 相同，但将片段放在容器 1 中(这是 FragmentUtilActivity 的 LinearLayout)。