我一直在努力追随the instructions on getting Spoon 1.1.14 to take screenshots for failing Espresso tests.

使用custom Espresso FailureHandler配置此功能的最佳方法是什么？

解决方法:

这就是我现在这样做的方式：

public class MainScreenTest extends BaseStatelessBlackBoxEspressoTest<LaunchActivity> {

    public MainScreenTest() {
        super(LaunchActivity.class);
    }

    public void testMainScreen() {
        // Unfortunately this must be explicitly called in each test :-(
        setUpFailureHandler();

        onView(withId(R.id.main_circle)).
                check(matches(isDisplayed()));
    }
}

我的基础Espresso测试类设置自定义FailureHandler(我喜欢使用基类来保存许多其他常用代码)：

public abstract class BaseStatelessBlackBoxEspressoTest<T extends Activity> extends BaseBlackBoxTest<T> {

    public BaseStatelessBlackBoxEspressoTest(Class clazz) {
        super(clazz);
    }

    @Before
    public void setUp() throws Exception {
        super.setUp();
        getActivity();
    }

    public void setUpFailureHandler() {
        // Get the test class and method.  These have to match those of the test
        // being run, otherwise the screenshot will not be displayed in the Spoon 
        // HTML output.  We cannot call this code directly in setUp, because at 
        // that point the current test method is not yet in the stack.
        StackTraceElement[] trace = Thread.currentThread().getStackTrace();
        String testClass = trace[3].getClassName();
        String testMethod = trace[3].getMethodName();

        Espresso.setFailureHandler(new CustomFailureHandler(
                getInstrumentation().getTargetContext(),
                testClass,
                testMethod));
    }

    private static class CustomFailureHandler implements FailureHandler {
        private final FailureHandler mDelegate;
        private String mClassName;
        private String mMethodName;

        public CustomFailureHandler(Context targetContext, String className, String methodName) {
            mDelegate = new DefaultFailureHandler(targetContext);
            mClassName = className;
            mMethodName = methodName;
        }

        @Override
        public void handle(Throwable error, Matcher<View> viewMatcher) {
            try {
                mDelegate.handle(error, viewMatcher);
            } catch (Exception e) {
                SpoonScreenshotAction.perform("espresso_assertion_failed", mClassName, mMethodName);
                throw e;
            }
        }
    }
}

…这是从the Gist posted by Square略微修改的截图代码：

/**
 * Source: https://github.com/square/spoon/issues/214#issuecomment-81979248
 */
public final class SpoonScreenshotAction implements ViewAction {
    private final String tag;
    private final String testClass;
    private final String testMethod;

    public SpoonScreenshotAction(String tag, String testClass, String testMethod) {
        this.tag = tag;
        this.testClass = testClass;
        this.testMethod = testMethod;
    }

    @Override
    public Matcher<View> getConstraints() {
        return Matchers.anything();
    }

    @Override
    public String getDescription() {
        return "Taking a screenshot using spoon.";
    }

    @Override
    public void perform(UiController uiController, View view) {
        Spoon.screenshot(getActivity(view), tag, testClass, testMethod);
    }

    private static Activity getActivity(View view) {
        Context context = view.getContext();
        while (!(context instanceof Activity)) {
            if (context instanceof ContextWrapper) {
                context = ((ContextWrapper) context).getBaseContext();
            } else {
                throw new IllegalStateException("Got a context of class "
                        + context.getClass()
                        + " and I don't know how to get the Activity from it");
            }
        }
        return (Activity) context;
    }    

    public static void perform(String tag, String className, String methodName) {
        onView(isRoot()).perform(new SpoonScreenshotAction(tag, className, methodName));
    }
}

我很乐意找到一种避免在每次测试中调用setUpFailureHandler()的方法 – 如果您对如何避免这种情况有一个好主意,请告诉我！