为什么我的 Robolectric 测试在使用 RealmResults 时会失败？答案

【问题标题】：Why are my Robolectric tests failing when using RealmResults?为什么我的 Robolectric 测试在使用 RealmResults 时会失败？
【发布时间】：2017-03-01 12:38:28
【问题描述】：

我在我的项目中使用 Realm，并且在试图让测试正常运行时遇到了一场噩梦。在您开始使用 RealmResults 从数据库中取出东西之前，我已经完成了所有测试。下面的代码是我得到结果的方式

private void getUser(){
    realm.beginTransaction();
    RealmResults<User> realmUsers = realm.where(User.class).findAll();
    user = realmUsers.first();
    realm.commitTransaction();
    Log.d("Test", user.getFirstName() + " " + user.getLastName());
}

只需返回存储在 Realm 中的所有结果。下面是测试完整的单元测试。

@RunWith(RobolectricGradleTestRunner.class)
@Config(constants = BuildConfig.class, sdk = Build.VERSION_CODES.LOLLIPOP, manifest = "src/main/AndroidManifest.xml")
@PowerMockIgnore({"org.mockito.*", "org.robolectric.*", "android.*"})
@PrepareForTest({Realm.class, RealmConfiguration.class,
        RealmQuery.class, RealmResults.class, RealmCore.class, RealmResults.class})
public class SecondActivityTest {

    @Rule
    public PowerMockRule rule = new PowerMockRule();

    private SecondActivity activity;

    private RealmResults<User> realmUsers;

    @Before
    public void setUp(){
    MockitoAnnotations.initMocks(this);

    // Setup Realm + Mock
    mockStatic(Realm.class);
    mockStatic(RealmConfiguration.class);
    mockStatic(RealmCore.class);
    mockStatic(RealmQuery.class);

    final Realm mockRealm = mock(Realm.class);
    doNothing().when(RealmCore.class);
    RealmCore.loadLibrary(any(Context.class));

    when(Realm.getDefaultInstance()).thenReturn(mockRealm);
    when(mockRealm.createObject(User.class)).thenReturn(new User());

    User userOne = new User("Matt", "Dunn");
    User userTwo = new User("Michael", "Stoddart");

    List<User> userList = Arrays.asList(userOne, userTwo);

    RealmQuery<User> realmQuery = mockRealmQuery();
    RealmResults<User> mockResults = mockRealmResults();

    when(mockResults.iterator()).thenReturn(userList.iterator());
    when(mockResults.size()).thenReturn(userList.size());

    when(mockResults.first()).thenReturn(userList.get(0));

    activity = Robolectric.setupActivity(SecondActivity.class);
}

    @Test
    public void checkActivityNotNull(){
        Assert.assertNotNull(activity);   
    }

    @SuppressWarnings("unchecked")
    private <T extends RealmObject> RealmQuery<T> mockRealmQuery() {
        return mock(RealmQuery.class);
    }

    @SuppressWarnings("unchecked")
    private <T extends RealmObject> RealmResults<T> mockRealmResults() {
        return mock(RealmResults.class);
    }
}

但是，即使我遵循了领域本身提供的指南，这仍然会引发以下异常

https://github.com/realm/realm-java/blob/master/examples/unitTestExample/src/test/java/io/realm/examples/unittesting/ExampleActivityTest.java

Method threw 'org.mockito.exceptions.misusing.NotAMockException' exception. Cannot evaluate io.realm.Realm$$EnhancerByMockitoWithCGLIB$$61d46d71.toString()

我是否错误地嘲笑了 RealmResults？还是完全不同的东西？

编辑：

测试失败时提供的完整堆栈跟踪是

java.lang.NullPointerException
    at com.example.mathewdunn.realmtest.activity.SecondActivity.getUser(SecondActivity.java:34)
    at com.example.mathewdunn.realmtest.activity.SecondActivity.onCreate(SecondActivity.java:29)
    at android.app.Activity.performCreate(Activity.java:5933)
    at org.robolectric.util.ReflectionHelpers.callInstanceMethod(ReflectionHelpers.java:195)
    at org.robolectric.util.ActivityController$1.run(ActivityController.java:122)
    at org.robolectric.shadows.ShadowLooper.runPaused(ShadowLooper.java:304)
    at org.robolectric.shadows.CoreShadowsAdapter$2.runPaused(CoreShadowsAdapter.java:45)
    at org.robolectric.util.ActivityController.create(ActivityController.java:118)
    at org.robolectric.util.ActivityController.create(ActivityController.java:129)
    at org.robolectric.util.ActivityController.setup(ActivityController.java:210)
    at org.robolectric.Robolectric.setupActivity(Robolectric.java:46)
    at com.example.mathewdunn.realmtest.SecondActivityTest.setUp(SecondActivityTest.java:83)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:24)
    at org.powermock.modules.junit4.rule.PowerMockStatement$1.run(PowerMockRule.java:83)
    at org.powermock.reflect.internal.WhiteboxImpl.performMethodInvocation(WhiteboxImpl.java:1899)
    at org.powermock.reflect.internal.WhiteboxImpl.doInvokeMethod(WhiteboxImpl.java:801)
    at org.powermock.reflect.internal.WhiteboxImpl.invokeMethod(WhiteboxImpl.java:666)
    at org.powermock.reflect.Whitebox.invokeMethod(Whitebox.java:401)
    at org.powermock.classloading.AbstractClassloaderExecutor.getResult(AbstractClassloaderExecutor.java:69)
    at org.powermock.classloading.AbstractClassloaderExecutor.executeWithClassLoader(AbstractClassloaderExecutor.java:59)
    at org.powermock.classloading.SingleClassloaderExecutor.execute(SingleClassloaderExecutor.java:67)
    at org.powermock.classloading.AbstractClassloaderExecutor.execute(AbstractClassloaderExecutor.java:43)
    at org.powermock.modules.junit4.rule.PowerMockStatement.evaluate(PowerMockRule.java:75)
    at org.robolectric.RobolectricTestRunner$2.evaluate(RobolectricTestRunner.java:251)
    at org.robolectric.RobolectricTestRunner.runChild(RobolectricTestRunner.java:188)
    at org.robolectric.RobolectricTestRunner.runChild(RobolectricTestRunner.java:54)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.robolectric.RobolectricTestRunner$1.evaluate(RobolectricTestRunner.java:152)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:119)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

调试测试时出现 NotAMock 异常。

编辑编辑：

进行一些更改后，现在抛出了一个替代异常。

com.thoughtworks.xstream.converters.ConversionException: Cannot convert type org.apache.tools.ant.Project to type org.apache.tools.ant.Project
---- Debugging information ----
message             : Cannot convert type org.apache.tools.ant.Project to type org.apache.tools.ant.Project
class               : org.apache.tools.ant.Project$1
required-type       : org.apache.tools.ant.Project$1
converter-type      : com.thoughtworks.xstream.converters.reflection.ReflectionConverter
path                : /org.powermock.modules.junit4.rule.PowerMockStatement$1/outer-class/fNext/next/outer-class/outer-class/dependencyResolver/dependencyResolver/project/isLoggingMessage/outer-class
line number         : 230
class[1]            : org.apache.tools.ant.Project
class[2]            : org.robolectric.internal.dependency.MavenDependencyResolver
class[3]            : org.robolectric.internal.dependency.CachedDependencyResolver
class[4]            : org.robolectric.RobolectricGradleTestRunner
class[5]            : org.robolectric.RobolectricTestRunner$HelperTestRunner
class[6]            : org.robolectric.RobolectricTestRunner$HelperTestRunner$1
class[7]            : org.junit.internal.runners.statements.RunBefores
class[8]            : org.powermock.modules.junit4.rule.PowerMockStatement
class[9]            : org.powermock.modules.junit4.rule.PowerMockStatement$1
version             : not available
-------------------------------

    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:456)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:281)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
    at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:70)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshallField(AbstractReflectionConverter.java:503)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:429)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:281)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
    at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:70)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshallField(AbstractReflectionConverter.java:503)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:429)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:281)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
    at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:70)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshallField(AbstractReflectionConverter.java:503)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:429)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:281)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
    at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:70)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshallField(AbstractReflectionConverter.java:503)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:429)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:281)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
    at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:70)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshallField(AbstractReflectionConverter.java:503)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:429)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:281)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
    at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:70)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshallField(AbstractReflectionConverter.java:503)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:429)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:281)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
    at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:70)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshallField(AbstractReflectionConverter.java:503)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:429)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:281)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
    at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:70)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshallField(AbstractReflectionConverter.java:503)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:429)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:281)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
    at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:70)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshallField(AbstractReflectionConverter.java:503)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.doUnmarshal(AbstractReflectionConverter.java:429)
    at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.unmarshal(AbstractReflectionConverter.java:281)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convert(TreeUnmarshaller.java:72)
    at com.thoughtworks.xstream.core.AbstractReferenceUnmarshaller.convert(AbstractReferenceUnmarshaller.java:70)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:66)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:50)
    at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:134)
    at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.unmarshal(AbstractTreeMarshallingStrategy.java:32)
    at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1230)
    at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:1214)
    at com.thoughtworks.xstream.XStream.fromXML(XStream.java:1085)
    at com.thoughtworks.xstream.XStream.fromXML(XStream.java:1076)
    at org.powermock.classloading.DeepCloner.clone(DeepCloner.java:55)
    at org.powermock.classloading.AbstractClassloaderExecutor.executeWithClassLoader(AbstractClassloaderExecutor.java:56)
    at org.powermock.classloading.SingleClassloaderExecutor.execute(SingleClassloaderExecutor.java:67)
    at org.powermock.classloading.AbstractClassloaderExecutor.execute(AbstractClassloaderExecutor.java:43)
    at org.powermock.modules.junit4.rule.PowerMockStatement.evaluate(PowerMockRule.java:75)
    at org.robolectric.RobolectricTestRunner$2.evaluate(RobolectricTestRunner.java:265)
    at org.robolectric.RobolectricTestRunner.runChild(RobolectricTestRunner.java:191)
    at org.robolectric.RobolectricTestRunner.runChild(RobolectricTestRunner.java:56)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.robolectric.RobolectricTestRunner$1.evaluate(RobolectricTestRunner.java:157)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:119)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)
    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 com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

干杯

【问题讨论】：

请包含整个堆栈跟踪。某个地方正在调用 Realm.toString()。
现在将编辑帖子@Kiskae
我可以建议您将活动中的数据层交互提取到另一个类中吗？测试设置表明您正在测试非常复杂的系统
@EugenMartynov 我通常使用 MVP，这只是一个测试项目，试图让它工作，你认为使用 MVP 对我有好处吗？
Cannot convert type org.apache.tools.ant.Project to type org.apache.tools.ant.Project 这是an error in Robolectric 3.1 and 3.2, but will be fixed in 3.3 quite soon? 半年前还不是“很快”，所以你应该高兴。

标签： java android mockito realm robolectric

【解决方案1】：

不完整的模拟

Realm test example 中缺少这些行：

    // The for(...) loop in Java needs an iterator, so we're giving it one that has items,
    // since the mock RealmResults does not provide an implementation. Therefore, anytime
    // anyone asks for the RealmResults Iterator, give them a functioning iterator from the
    // ArrayList of Persons we created above. This will allow the loop to execute.
    when(people.iterator()).thenReturn(personList.iterator());

    // Return the size of the mock list.
    when(people.size()).thenReturn(personList.size());

解释在代码注释中 - 基本上 RealmResults 就像一个 Realm 'Cursor' 并且不包含任何数据本身，但作为存储在 Realm 中的对象的代理。

考虑到这个事实，一个模拟实例没有任何迭代器，很明显你必须重定向你在这个 RealmResults 上的迭代到一个不同的、功能齐全的 List 实例 - @987654324 @在你的情况下：

    when(mockResults.iterator()).thenReturn(userList.iterator());
    when(mockResults.size()).thenReturn(userList.size());

这将允许您迭代并获取模拟的 RealmResults 实例的大小。

由于您在 getUser() 方法中的 RealmResults 上调用 first()，因此您也需要模拟此方法：

    when(mockResults.first()).thenReturn(userList.get(0));

另外，请注意，在您的 getUser() 方法中调用 realm.beginTransaction() 和 realm.commitTransaction() 是多余的，因为您没有执行任何写入操作。您可以安全地删除它们，或者也可以模拟它们：

    doCallRealMethod().when(mockRealm).beginTransaction();
    doCallRealMethod().when(mockRealm).commitTransaction();

【讨论】：

我已经添加了您建议的两个语句以及更多语句，现在我得到了另一个空指针。 when(mockRealm.where(User.class).findAll()).thenReturn(mockResults);
@drofnnuD 错误是什么？另外，现在尝试删除所有 when(realmQuery... 调用，因为您还不需要它们 - 也许您不小心用它们重新定义了模拟
@drofnnuD 查看我对模拟 realmUsers.first() 调用的编辑
我已经进行了您建议的编辑并更新了主要问题，因此这是当前正在运行的测试方法。它仍然失败，抛出我在主要问题正文中发布的相同 NullPointer
@drofnnuD beginTransaction() 和 commitTransaction() 怎么样？您是否尝试过删除它们，或者使用 doCallRealMethod().when(mockRealm.beginTransaction()) 或 doNothing().when(mockRealm.beginTransaction()) 等来模拟它们？