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使用下面的代码来测试异常Flow和MockK

@Test 乐趣given network error returned from repos, should throw exception() = testCoroutineScope.runBlockingTest {

    // GIVEN
    every { postRemoteRepository.getPostFlow() } returns flow<List<PostDTO>> {
        emit(throw Exception("Network Exception"))
    }

    // WHEN
    var expected: Exception? = null
    useCase.getPostFlow()
        .catch { throwable: Throwable ->
            expected = throwable as Exception
            println("⏰ Expected: $expected")
        }
        .launchIn(testCoroutineScope)

    // THEN
    println("⏰ TEST THEN")

    Truth.assertThat(expected).isNotNull()
    Truth.assertThat(expected).isInstanceOf(Exception::class.java)
    Truth.assertThat(expected?.message).isEqualTo("Network Exception")
}

和版画

⏰ TEST THEN
⏰ Expected: java.lang.Exception: Network Exception

并且测试失败了

expected not to be: null

我测试的方法是

fun getPostFlow(): Flow<List<Post>> {
    return postRemoteRepository.getPostFlow()

            //  This method is just to show flowOn below changes current thread
        .map {
            // Runs in IO Thread DefaultDispatcher-worker-2
            println("⏰ PostsUseCase map() FIRST thread: ${Thread.currentThread().name}")
           it
        }
        .flowOn(Dispatchers.IO)
        .map {
            // Runs in Default Thread DefaultDispatcher-worker-1
            println("⏰ PostsUseCase map() thread: ${Thread.currentThread().name}")
            mapper.map(it)
        }
        // This is a upstream operator, does not leak downstream
        .flowOn(Dispatchers.Default)

}

这不是一个完全实用的功能，只是为了检查 Dispatchers 如何使用 Flow 和测试。

在撰写我评论的问题时.flowOn(Dispatchers.IO)，测试通过的最重要的问题。还将 Dispatchers.IO 更改为 Dispatchers.Default 并导致测试通过。我认为这是由于使用了不同的线程。

1-是否有一种功能或方法可以在不修改代码的情况下将所有 flowOn 方法设置为同一个线程？

这次我尝试测试成功场景

    @Test
    fun `given data returned from api, should have data`() = testCoroutineScope.runBlockingTest {

        // GIVEN
        coEvery { postRemoteRepository.getPostFlow() } returns flow { emit(postDTOs) }
        every { dtoToPostMapper.map(postDTOs) } returns postList

        val actual = postList

        // WHEN
        val expected = mutableListOf<Post>()
//        useCase.getPostFlow().collect {postList->
//            println("⏰ Collect: ${postList.size}")
//
//            expected.addAll(postList)
//        }

        val job = useCase.getPostFlow()
            .onEach { postList ->
                println("⏰ Collect: ${postList.size}")

                expected.addAll(postList)
            }
            .launchIn(testCoroutineScope)

        job.cancel()

        // THEN
        println("⏰ TEST THEN")
        Truth.assertThat(expected).containsExactlyElementsIn(actual)
    }

当我尝试截取被注释掉的片段时，测试失败

java.lang.IllegalStateException: This job has not completed yet

job如果已取消，似乎测试可以通过launchIn，返回的测试job通过。

2- 为什么收集作业没有被取消，它只在第一次flowOn使用时发生Dispatchers.IO？

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0 回答 0