Unit testing 当单元测试我的ViewModel时，列表总是返回空

我试图学习单元测试，我将代码分解到MVVM（I）体系结构中，但是当我运行testParseToList（）测试函数时，它总是返回一个空列表，我不知道为什么。我担心这可能和MVVM（I）的I部分有关，也可能和我是否正确地模拟了viewmodel有关。我从我最简单的viewmodel开始，希望在进入更复杂的概念之前先掌握这些概念

OfflineViewModelUnitTest.kt

@RunWith(JUnit4::class)
class OfflineViewModelUnitTest {

    @get:Rule
    val rule = InstantTaskExecutorRule()

    @Mock
    var offlineViewModel: OfflineViewModel = OfflineViewModel(OfflineInteractorImpl())

    @Before
    fun setup() {
        MockitoAnnotations.initMocks(this)
        DaggerOfflineViewModelComponent.builder()
            .offlineInteractorImplModule(OfflineInteractorImplModule())
            .build()
            .inject(offlineViewModel)

//        this.offlineViewModel = OfflineViewModel(OfflineInteractorImpl())
    }

    @Test
    fun testParseToList() {

        val test = offlineViewModel.parseTextToList("dried bonito extract,\n" +
                "    ketchup,\n" +
                "    millet,\n" +
                "    corn & wheat protein")

        val a = "dried bonito extract"
        val b = "ketchup"
        val c = "millet"
        val d = "corn & wheat protein"

        val expectedResult = listOf(a, b, c, d)

        assertEquals(expectedResult, test)
    }
}

class OfflineViewModel(private val offlineInteractor: OfflineInteractor): ViewModel() {

    init {
        DaggerOfflineViewModelComponent.builder()
            .offlineInteractorImplModule(OfflineInteractorImplModule())
            .build()
            .inject(this)
    }
    fun parseTextToList(firebaseVisionTextString: String): MutableList<String> {
        Log.d("here it is", firebaseVisionTextString)
        return offlineInteractor.parseTextToList(firebaseVisionTextString)
    }

    fun readCsvFromAssetFolder(inputStream: InputStream): List<String>{
        return offlineInteractor.readCsvFromAssetFolder(inputStream)
    }
}

class OfflineInteractorImpl: OfflineInteractor {

    override fun parseTextToList(firebaseVisionTextString: String): MutableList<String> {

            val ingredientsList: MutableList<String> = firebaseVisionTextString.split(",").map { it.trim() }.toMutableList()

            return ingredientsList
    }

    override fun readCsvFromAssetFolder(inputStream: InputStream): List<String> {
        val csvLine: ArrayList<String> = ArrayList()
        var content: Array<String>?
        try
        {
            val br = BufferedReader(InputStreamReader(inputStream))
            for (line in br.lines())
            {
                content = line.split((",").toRegex()).dropLastWhile{ it.isEmpty() }.toTypedArray()
                csvLine.add(content[0].substringBefore(";"))
            }
            br.close()
        }
        catch (e: IOException) {
            e.printStackTrace()
        }
        return csvLine
    }
}

离线视图模型.kt

@RunWith(JUnit4::class)
class OfflineViewModelUnitTest {

    @get:Rule
    val rule = InstantTaskExecutorRule()

    @Mock
    var offlineViewModel: OfflineViewModel = OfflineViewModel(OfflineInteractorImpl())

    @Before
    fun setup() {
        MockitoAnnotations.initMocks(this)
        DaggerOfflineViewModelComponent.builder()
            .offlineInteractorImplModule(OfflineInteractorImplModule())
            .build()
            .inject(offlineViewModel)

//        this.offlineViewModel = OfflineViewModel(OfflineInteractorImpl())
    }

    @Test
    fun testParseToList() {

        val test = offlineViewModel.parseTextToList("dried bonito extract,\n" +
                "    ketchup,\n" +
                "    millet,\n" +
                "    corn & wheat protein")

        val a = "dried bonito extract"
        val b = "ketchup"
        val c = "millet"
        val d = "corn & wheat protein"

        val expectedResult = listOf(a, b, c, d)

        assertEquals(expectedResult, test)
    }
}

class OfflineViewModel(private val offlineInteractor: OfflineInteractor): ViewModel() {

    init {
        DaggerOfflineViewModelComponent.builder()
            .offlineInteractorImplModule(OfflineInteractorImplModule())
            .build()
            .inject(this)
    }
    fun parseTextToList(firebaseVisionTextString: String): MutableList<String> {
        Log.d("here it is", firebaseVisionTextString)
        return offlineInteractor.parseTextToList(firebaseVisionTextString)
    }

    fun readCsvFromAssetFolder(inputStream: InputStream): List<String>{
        return offlineInteractor.readCsvFromAssetFolder(inputStream)
    }
}

class OfflineInteractorImpl: OfflineInteractor {

    override fun parseTextToList(firebaseVisionTextString: String): MutableList<String> {

            val ingredientsList: MutableList<String> = firebaseVisionTextString.split(",").map { it.trim() }.toMutableList()

            return ingredientsList
    }

    override fun readCsvFromAssetFolder(inputStream: InputStream): List<String> {
        val csvLine: ArrayList<String> = ArrayList()
        var content: Array<String>?
        try
        {
            val br = BufferedReader(InputStreamReader(inputStream))
            for (line in br.lines())
            {
                content = line.split((",").toRegex()).dropLastWhile{ it.isEmpty() }.toTypedArray()
                csvLine.add(content[0].substringBefore(";"))
            }
            br.close()
        }
        catch (e: IOException) {
            e.printStackTrace()
        }
        return csvLine
    }
}

---

就像第二个所说的，由于您模拟了offlineViewModel，它将返回一个空字符串，除非您使用when（）为它定义要返回的内容

---

来源：

offlineViewModel

是您正在测试的类，但您模拟了它。你不应该模仿被测试的类。此外，如果创建模拟，则需要为其定义行为，否则它将只返回

null

（或与之等效的原语）。