ViewModelStateVerifier.kt

fun assertThat(someViewModel: SomeViewModel): ViewModelStateVerifier { // inspired by Hamcrest
    return ViewModelStateVerifier(someViewModel)
}

class ViewModelStateVerifier(private val someViewModel: SomeViewModel) {

    fun loaderIsShown(): ViewModelStateVerifier {
        assertTrue(someViewModel.getLoaderState().value)
        return this
    }

    fun loaderIsHidden(): ViewModelStateVerifier {
        assertFalse(someViewModel.getLoaderState().value)
        return this
    }

    fun errorIsShown(): ViewModelStateVerifier {
        assertTrue(someViewModel.getErrorState().value)
        return this
    }

    fun errorIsHidden(): ViewModelStateVerifier {
        assertFalse(someViewModel.getErrorState().value)
        return this
    }

    fun contentIsHidden(): ViewModelStateVerifier {
        assertEquals(ContentState.Hidden, someViewModel.getContentState().value)
        return this
    }

    fun contentIsShow(data: String): ViewModelStateVerifier {
        assertEquals(ContentState.Shown(data), someViewModel.getContentState().value)
        return this
    }
}