Driving the Activity Lifecycle

Before Robolectric 2.2, most tests created Activities by calling constructors directly, (new MyActivity()) and then manually calling lifecycle methods such as onCreate(). Also widely used were a set of methods in ShadowActivity (for instanceShadowActivity.callOnCreate()) that are precursors to ActivityController.

It was a mess. The ActivityController is a Robolectric API that changes all of this. Its goal is to mimic how Android creates your Activities and drives them through their lifecycle.

ActivityController is a fluent API that was introduced in Robolectric 2.0 and is now required in 2.2. In addition to calling methods like onCreate(), it ensures that the internal state of the Activity is consistent with the lifecycle. This includes attaching the Activity to the Window and making system services like the LayoutInflater available.

//ActivityController是一个流畅的api 从2.2版本开始可用。除了调用像onCreate()方法之外，它保证了actvity的状态和生命周期一致。

What do I do now?

You don't generally create an ActivityController directly. Use Robolectric.buildActivity() to get started. For the most basic of tests where you simply need an initialized Activity, you can often get away with the following line:

//一般通常不会直接创建activitycontroller，而是使用Robolectric.buildActivity方法。如下：

Activity activity = Robolectric.buildActivity(MyAwesomeActivity.class).create().get();

This will create a new instance of MyAwesomeActivity and call through the life cycle to onCreate().

//这会创建一个activity的实例，然后调用到oncreate()生命周期方法

Want to check that something happens during onResume() but not onCreate()? Easy!

//想要查看onresume方法里面做了什么而不是oncreate?好办：

ActivityController controller = Robolectric.buildActivity(MyAwesomeActivity.class).create().start();
Activity activity = controller.get();
// assert that something hasn't happened
activityController.resume();
// assert it happened!

Similar methods are included for start(), pause(), stop(), and destroy(). So, if you want to test the full creation lifecycle:

//相似的方法也包括在 start(), pause(), stop(), and destroy()中

Activity activity = Robolectric.buildActivity(MyAwesomeActivity.class).create().start().resume().visible().get();

You can simulate starting the Activity with an intent:

//模拟使用一个intent来开启activity

Intent intent = new Intent(Intent.ACTION_VIEW);
Activity activity = Robolectric.buildActivity(MyAwesomeActivity.class).withIntent(intent).create().get();

... or restore saved instance state:

//或者模拟开启一个带有bundle的activity

Bundle savedInstanceState = new Bundle();
Activity activity = Robolectric.buildActivity(MyAwesomeActivity.class)
    .create()
    .restoreInstanceState(savedInstanceState)
    .get();

Check out the ActivityController Java Docs to see more public methods available for your testing needs.

Wait, What's This visible() Nonsense?

//visible()是不是废话啊？

Turns out that in a real Android app, the view hierarchy of an Activity is not attached to the Window until sometime afteronCreate() is called. Until this happens, the Activity's views do not report as visible. This means you can't click on them (amongst other unexpected behavior). The Activity's hierarchy is attached to the Window on a device or emulator afteronPostResume() on the Activity. Rather than make assumptions about when the visibility should be updated, Robolectric puts the power in the developer's hands when writing tests.

//当oncreate方法调用了activity仍然没有visible，这意味着你不能点击（或者其他的用户行为）。hierarche被添加到window上是直到onPostresume（）方法被调用，这时候才可以和用户交互。robolectric把这个更改状态的权利交到开发者手中

So when do you call it? Whenever you're interacting with the views inside the Activity. Methods like Robolectric.clickOn()require that the view is visible and properly attached in order to function. You should call visible() after create().

//所以我们什么时候调用它呢？当你要和activity中的view交互时，你应该在create之后调用visible