Turbine

12345678910111213141516171819202122@Test
fun `emits loading then content`() = runTest {
    viewModel.state.test {
        assertEquals(UiState.Loading, awaitItem())

        viewModel.load()

        val ready = awaitItem() as UiState.Ready
        assertEquals(3, ready.books.size)

        // Fails the test if anything else was emitted.
        cancelAndIgnoreRemainingEvents()
    }
}

@Test
fun `propagates errors`() = runTest {
    failingFlow.test {
        assertEquals(1, awaitItem())
        assertTrue(awaitError() is IOException)
    }
}

1234567891011121314151617@Test
fun `debounces rapid input`() = runTest {
    // runTest's scheduler skips delays instantly — no real waiting.
    searchViewModel.results.test {
        skipItems(1)                       // initial empty state

        searchViewModel.onQueryChanged("du")
        searchViewModel.onQueryChanged("dun")
        searchViewModel.onQueryChanged("dune")

        advanceTimeBy(301)                 // past the debounce window

        val results = awaitItem()
        assertEquals(1, results.size)      // only the last query ran
        cancelAndIgnoreRemainingEvents()
    }
}