Testing a click on an Android ListView with ActivityUnitTestCase

Question

I have implemented a ListView that starts a new Activity when a list item is clicked. When I test it manually, it works perfectly. But when I try to do an automated test with ActivityUnitTestCase, I get a NullPointerException as though the ListView was empty.

MainActivity (partial):

public class MainActivity extends ListActivity {

  @Override
  protected void onResume() {
    super.onResume();

    String[] items = new String[] {"item 1", "item 2"};
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, items);
    setListAdapter(adapter);

    getListView().setOnItemClickListener(new OnItemClickListener () {

      @Override
      public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        TextView clickedItem = (TextView) view;
        CharSequence clickedItemText = clickedItem.getText(); // throws a NullPointerException when running testWithPerformItemClick()!
        Intent intent = new Intent(MainActivity.this, ItemDisplayActivity.class);
        intent.putExtra("parameter", clickedItemText);
        startActivity(intent);
      }
    });
  }
}

The test code that fails:

public class MainActivityTest extends ActivityUnitTestCase<MainActivity> {

  ListView listView;
  View child0;

  public MainActivityTest() {
    super(MainActivity.class);
  }

  private void setUpTest() {
    MainActivity activity = startActivity(new Intent(), null, null);
    getInstrumentation().callActivityOnStart(activity);
    getInstrumentation().callActivityOnResume(activity);
    listView = (ListView) activity.findViewById(android.R.id.list);
    child0 = listView.getChildAt(0); // returns null!
  }

  public void testWithPerformClick() {
    setUpTest();

    child0.performClick(); // throws a NullPointerException!

    Intent startedIntent = getStartedActivityIntent();
    assertEquals("item 1", startedIntent.getStringExtra("parameter"));
  }

  public void testWithPerformItemClick() {
    setUpTest();
    long itemId = listView.getAdapter().getItemId(0);

    listView.performItemClick(child0, 0, itemId); // throws a NullPointerException!

    Intent startedIntent = getStartedActivityIntent();
    assertEquals("item 1", startedIntent.getStringExtra("parameter"));
  }

Both test methods fail because listView.getChildAt(0) returns null. Why is the ListView empty? How can I force it to update itself with the right children?

Cooney

Have you tried the performItemClick()? – Nipha

Using performItemClick(), the code gets a little bit farther, up to the clickedItem.getText() part of the onItemClick method. Once there, a NPE is raised because the provided view is null (because getChildAt(0) returns null). Updating the issue description to make this clearer. – Cooney

Answer 1

According to the documentation, If you prefer a functional test you should use ActivityInstrumentationTestCase2. To perform a click it works better. The @fewe answer is right, you have to wait the list to be drawn, to wait the fragment to be loaded you can use getInstrumentation().waitForIdleSync();

Try something like this.

public class ActivityTests extends
    ActivityInstrumentationTestCase2<Activity>

final ListView list = (ListView) mActivity.findViewById(R.id.listId);
         assertNotNull("The list was not loaded", list);
         getInstrumentation().runOnMainSync(new Runnable() {
             @Override
             public void run() {

                 list.performItemClick(list.getAdapter().getView(position, null, null),
                         position, list.getAdapter().getItemId(position));
             }

         });

 getInstrumentation().waitForIdleSync();

Then you cant test, for example, if a fragment was loaded.

  mFragment frag = mActivity.getFragment();
  assertNotNull("Fragment was not loaded", frag);

Neuburger

Answer 2

This is because the listview isn't drawn yet. You should wait for it to be drawn before trying to access its cells

Distilled

That would make sense. But how do you make the program wait for the list's drawing? What line of code should be added in the setUpTest() method? – Cooney

I have to say I am looking for a best practice on this matter as well. For now, I use a Thread.sleep call. – Distilled