使用Powermock2和Kotlin模拟静态类

Question

在Android中我一直在使用Powermock的1.6.1版本,所有这些实现对于静态都非常有用.当我改为2.0.0-beta.5时,它现在根本不起作用.实际上,它甚至没有从我之前的1.6.1升级到1.7.1.

我有这个实现:

// Power Mockito
testImplementation "org.powermock:powermock-api-mockito2:2.0.0-beta.5"
testImplementation "org.powermock:powermock-module-junit4-rule-agent:2.0.0-beta.5"
testImplementation "org.powermock:powermock-module-junit4:2.0.0-beta.5"
//testImplementation 'org.powermock:powermock-module-junit4-rule:2.0.0-beta.5'

// Mockito
testImplementation "org.mockito:mockito-core:2.11.0"
testImplementation "com.nhaarman:mockito-kotlin-kt1.1:1.5.0"
androidTestImplementation("com.nhaarman:mockito-kotlin-kt1.1:1.5.0", {
    exclude group: 'org.mockito', module: 'mockito-core'
})
androidTestImplementation 'org.mockito:mockito-android:2.11.0'

而我正试图以与1.6.1相同的方式模拟静态:

@RunWith(PowerMockRunner::class)
@PrepareForTest(SharedPreferencesHelper.Companion::class, ConfigUseCaseTests::class)
class ConfigUseCaseTests {

    lateinit var context: Context

    @Before
    fun setUp() {
        context = mock()
    }

    @Test
    fun getConfigs_fromJson() {
        PowerMockito.mockStatic(SharedPreferencesHelper.Companion::class.java)

        val instance = mock<SharedPreferencesHelper.Companion>()
        doReturn("foo")
                .whenever(instance)
                .loadString(isA(), anyString(), anyString(), anyString())
//        whenever(instance.loadString(isA(), anyString(), anyString(), anyString())).thenReturn("foo") // This shows the same error
        PowerMockito.whenNew(SharedPreferencesHelper.Companion::class.java)
                .withAnyArguments()
                .thenReturn(instance)

        val mockedFoo = instance.loadString(context, "", "", "") // This shows "foo"

        val mockedCompanion = SharedPreferencesHelper.loadString(context, "", "", "") // This is throwing NullPointerException

        Assert.assertEquals(mockedCompanion, "foo")
    }
}

我的SharedPreferencesHelper看起来像:

class SharedPreferencesHelper {
    companion object {

        @Suppress("NON_FINAL_MEMBER_IN_OBJECT")
        open fun loadString(context: Context, fileName: String, key: String, defaultValue: String?): String? {
            val sharedPreferences = getWithFileName(context, fileName)
            return if (!sharedPreferences.contains(key)) {
                defaultValue
            } else {
                sharedPreferences.getString(key, defaultValue)
            }
        }
    }
}

我试过玩,open但它不起作用.

例外:(我根本不明白)

java.lang.NullPointerException
    at my.package.ConfigUseCaseTests.getConfigs_fromJson(ConfigUseCaseTests.kt:45)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.internal.runners.TestMethod.invoke(TestMethod.java:68)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:326)
    at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:89)
    at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:97)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.executeTest(PowerMockJUnit44RunnerDelegateImpl.java:310)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.executeTestInSuper(PowerMockJUnit47RunnerDelegateImpl.java:131)

我可以说,有时IT工作!我正在添加视频,因为它看起来很奇怪它有时会发生:https: //youtu.be/YZObVLcERBo(在中间和末尾观看)

Answer 1

编译时创建伴生对象的方式是在周围的类中创建一个静态字段。它在静态范围内实例化（在实例化测试之前）。

这是反编译时的样子Java：

public final class SharedPreferencesHelper {
  public static final SharedPreferencesHelper.Companion Companion = new 
  SharedPreferencesHelper.Companion((DefaultConstructorMarker)null);
  // ...
}

为此，您必须使用模拟分配给定字段，而不是拦截对象的创建Companion。这甚至不需要使用PowerMock并且可以通过反射来完成：https://dzone.com/articles/how-to-change-private-static-final-fields