如果你在使用Espresso时发生了错误，而你恰好看到了我的这篇文章，可以看看下面有没有你遇到的问题。
一：Error:Conflict with dependency ‘com.android.support:support-annotations’. Resolved versions for app (26.0.2) and test app (23.1.1) differ. See http://g.co/androidstudio/app-test-app-conflict for details.
解决：
build.gradle文件中的依赖改成下面这样子
androidTestCompile ‘com.android.support.test.espresso:espresso-core:2.2.2’, {
exclude group: ‘com.android.support’, module: ‘support-annotations’
}
二：编写.java文件，找不到@RunWith()注解类
解决：
build.gradle文件中junit依赖要用testCompile，但不能用junit的debugCompile依赖
三：java.lang.RuntimeException: No activities found. Did you forget to launch the activity by calling getActivity() or startActivitySync or similar?
解决：
加@Rule注解到这句上：public ActivityTestRule mActivityTestRule = new ActivityTestRule<>(<YourActivity>.class);
四：Test running failed: Unable to find instrumentation info for: ComponentInfo{<yourpackage>/android.support.test.runner.AndroidJUnitRunner}
解决：
build.gragle文件中找到加这句（在android{}中）：android {
defaultConfig {
testInstrumentationRunner “android.support.test.runner.AndroidJUnitRunner”
}
}
五：android.support.test.espresso.NoActivityResumedException: No activities in stage RESUMED. Did you forget to launch the activity. (test.getActivity() or similar)?
解决：手机屏幕必须保持打开
六：junit.framework.AssertionFailedError: No tests found in <yourtest>
解决：
build.gragle文件中找到加这句（在android{}中）：android {
defaultConfig {
testInstrumentationRunner “android.support.test.runner.AndroidJUnitRunner”
}
}
最后附上Espresso的官方文档地址：https://developer.android.com/training/testing/espresso/setup
