我在尝试为使用 observeOn(AndroidSchedulers.mainThread())
的演示者运行 JUnit 测试时遇到 RuntimeException。
由于它们是纯 JUnit 测试而不是 Android Instrumentation 测试,因此它们无法访问 Android 依赖项,导致我在执行测试时遇到以下错误:
java.lang.ExceptionInInitializerError
at io.reactivex.android.schedulers.AndroidSchedulers$1.call(AndroidSchedulers.java:35)
at io.reactivex.android.schedulers.AndroidSchedulers$1.call(AndroidSchedulers.java:33)
at io.reactivex.android.plugins.RxAndroidPlugins.callRequireNonNull(RxAndroidPlugins.java:70)
at io.reactivex.android.plugins.RxAndroidPlugins.initMainThreadScheduler(RxAndroidPlugins.java:40)
at io.reactivex.android.schedulers.AndroidSchedulers.<clinit>(AndroidSchedulers.java:32)
…
Caused by: java.lang.RuntimeException: Method getMainLooper in android.os.Looper not mocked. See http://g.co/androidstudio/not-mocked for details.
at android.os.Looper.getMainLooper(Looper.java)
at io.reactivex.android.schedulers.AndroidSchedulers$MainHolder.<clinit>(AndroidSchedulers.java:29)
...
java.lang.NoClassDefFoundError: Could not initialize class io.reactivex.android.schedulers.AndroidSchedulers
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)
…
最佳答案
发生此错误是因为 AndroidSchedulers.mainThread()
返回的默认调度程序是 LooperScheduler
的一个实例,并且依赖于 JUnit 测试中不可用的 Android 依赖项。
我们可以通过在运行测试之前使用不同的调度程序初始化 RxAndroidPlugins
来避免这个问题。您可以在 @BeforeClass
方法中执行此操作,如下所示:
@BeforeClass
public static void setUpRxSchedulers() {
Scheduler immediate = new Scheduler() {
@Override
public Disposable scheduleDirect(@NonNull Runnable run, long delay, @NonNull TimeUnit unit) {
// this prevents StackOverflowErrors when scheduling with a delay
return super.scheduleDirect(run, 0, unit);
}
@Override
public Worker createWorker() {
return new ExecutorScheduler.ExecutorWorker(Runnable::run);
}
};
RxJavaPlugins.setInitIoSchedulerHandler(scheduler -> immediate);
RxJavaPlugins.setInitComputationSchedulerHandler(scheduler -> immediate);
RxJavaPlugins.setInitNewThreadSchedulerHandler(scheduler -> immediate);
RxJavaPlugins.setInitSingleSchedulerHandler(scheduler -> immediate);
RxAndroidPlugins.setInitMainThreadSchedulerHandler(scheduler -> immediate);
}
或者您可以创建一个自定义 TestRule
,让您可以跨多个测试类重用初始化逻辑。
public class RxImmediateSchedulerRule implements TestRule {
private Scheduler immediate = new Scheduler() {
@Override
public Disposable scheduleDirect(@NonNull Runnable run, long delay, @NonNull TimeUnit unit) {
// this prevents StackOverflowErrors when scheduling with a delay
return super.scheduleDirect(run, 0, unit);
}
@Override
public Worker createWorker() {
return new ExecutorScheduler.ExecutorWorker(Runnable::run);
}
};
@Override
public Statement apply(final Statement base, Description description) {
return new Statement() {
@Override
public void evaluate() throws Throwable {
RxJavaPlugins.setInitIoSchedulerHandler(scheduler -> immediate);
RxJavaPlugins.setInitComputationSchedulerHandler(scheduler -> immediate);
RxJavaPlugins.setInitNewThreadSchedulerHandler(scheduler -> immediate);
RxJavaPlugins.setInitSingleSchedulerHandler(scheduler -> immediate);
RxAndroidPlugins.setInitMainThreadSchedulerHandler(scheduler -> immediate);
try {
base.evaluate();
} finally {
RxJavaPlugins.reset();
RxAndroidPlugins.reset();
}
}
};
}
}
然后您可以将其应用于您的测试类(class)
public class TestClass {
@ClassRule public static final RxImmediateSchedulerRule schedulers = new RxImmediateSchedulerRule();
@Test
public void testStuff_stuffHappens() {
...
}
}
这两种方法都将确保在执行任何测试之前和访问 AndroidSchedulers
之前覆盖默认调度程序。
使用即时调度程序覆盖 RxJava 调度程序以进行单元测试也将确保被测试代码中的 RxJava 用法同步运行,这将使编写单元测试变得更加容易。
来源:
https://www.infoq.com/articles/Testing-RxJava2
https://medium.com/@peter.tackage/overriding-rxandroid-schedulers-in-rxjava-2-5561b3d14212
关于Android RxJava 2 JUnit 测试 - android.os.Looper 中的 getMainLooper 未模拟 RuntimeException,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43356314/