Android Espresso onData with doesNotExist

Issue

I am trying to verify that a ListView does not contain a particular item. Here’s the code I’m using:

onData(allOf(is(instanceOf(Contact.class)), is(withContactItemName(is("TestName")))))
      .check(doesNotExist());

When the name exists, I correctly get an error because of check(doesNotExist()). When the name does not exist, I get the following error, because allOf(...) doesn’t match anything:

Caused by: java.lang.RuntimeException: No data found matching: 
(is an instance of layer.sdk.contacts.Contact and is with contact item name:
is "TestName")

How can I get functionality like onData(...).check(doesNotExist())?

EDIT:

I have a terrible hack to get the functionality I’d like by using try/catch and inspecting the event’s getCause(). I would love to replace this with a good technique.

Solution

According to Espresso samples you must not use onData(...) to check if view doesn’t exists in adapter. Check this out – link. Read "Asserting that a data item is not in an adapter" part. You have to use a matcher together with onView() that finds the AdapterView.

Based on Espresso samples from link above:

1. matcher:

    private static Matcher<View> withAdaptedData(final Matcher<Object> dataMatcher) {
        return new TypeSafeMatcher<View>() {
   
            @Override
            public void describeTo(Description description) {
                description.appendText("with class name: ");
                dataMatcher.describeTo(description);
            }
   
            @Override
            public boolean matchesSafely(View view) {
                if (!(view instanceof AdapterView)) {
                    return false;
                }
   
                @SuppressWarnings("rawtypes")
                Adapter adapter = ((AdapterView) view).getAdapter();
                for (int i = 0; i < adapter.getCount(); i++) {
                    if (dataMatcher.matches(adapter.getItem(i))) {
                        return true;
                    }
                }
                return false;
            }
        };
    }
   

2. then onView(...), where R.id.list is the id of your adapter ListView:

    @SuppressWarnings("unchecked")
    public void testDataItemNotInAdapter(){
        onView(withId(R.id.list))
            .check(matches(not(withAdaptedData(is(withContactItemName("TestName"))))));
    }
   

And one more suggestion – to avoid writing is(withContactItemName(is("TestName")) add below code to your matcher:

    public static Matcher<Object> withContactItemName(String itemText) {
        checkArgument( itemText != null );
        return withContactItemName(equalTo(itemText));
    }

then you’ll have more readable and clear code is(withContactItemName("TestName")

Answered By – denys

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