Android Programming: The Big Nerd Ranch Guide, 4th Edition

Writing Tests

Now that your initial setUp() function is written, you are ready to write your tests. A test is a function in your test class annotated with @Test.

Start by writing a test that asserts existing behavior in SoundViewModel: The title property is connected to the Sound’s name property. Write a function that tests this (Listing 20.8).

Listing 20.8  Testing the title property (SoundViewModelTest.kt)

class SoundViewModelTest {
    ...
    @Before
    fun setUp() {
        ...
    }

    @Test
    fun exposesSoundNameAsTitle() {
        assertThat(subject.title, `is`(sound.name))
    }
}

Two functions will show up red: the assertThat(…) function and the is(…) function. Key in Option-Return (Alt-Enter) on assertThat(…) and select Assert.assertThat(…) from