@Before
    public void initValidStrings() {
        // Produce a string with valid ending.
        mStringWithValidEnding = "Random " + MainActivity.VALID_ENDING;

        // Get one of the available coffee preparations.
        mValidStringToBeTyped = MainActivity.COFFEE_PREPARATIONS.get(0);
    }
{@link ActivityScenarioRule} will create and launch of the activity for you.
ui/espresso/CustomMatcherSample/app/src/sharedTest/java/com/example/android/testing/espresso/CustomMatcherSample/HintMatchersTest.java