- Enclosing class:
Nested Class Summary
Enum Constant SummaryEnum ConstantDescriptionA mode that simulates an android instrumentation test threading model, which has a separate test thread distinct from the main looper thread.Deprecated.use LooperMode.PAUSEDA mode that more accurately models real Android's
Methods inherited from class java.lang.Enum
clone, compareTo, describeConstable, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf
Enum Constant Details
LEGACYDeprecated.use LooperMode.PAUSEDRobolectric's default threading model prior to 4.4.
There is only a single Looper thread - with tests and all posted Looper tasks executing on that thread.
There are multiple problems with this mode. Some of the major ones are:
- The default
UNPAUSEDstate will execute tasks posted to a
Looperinline synchronously. This differs from real Android behaviour, and can cause issues with code that expects/enforces that posted tasks execute in the correct order, such as RecyclerViews.
Schedulerlist of Runnables can get out of sync with the Looper's
MessageQueue, causing deadlocks or other race conditions.
Schedulerkeeps its own time value, which can get out of sync.
Loopertasks execute in the main thread, causing errors for code that enforces that it runs on a non-main
- The default
PAUSEDpublic static final LooperMode.Mode PAUSEDA mode that more accurately models real Android's
Conceptually LooperMode.PAUSED is similar to the LEGACY
Scheduler.IdleState.PAUSEDin the following ways:
- Tests run on the main looper thread
- Tasks posted to the main
Looperare not executed automatically, and must be explicitly executed via
ShadowLooper.idle(). This guarantees execution order correctness
SystemClocktime is frozen, and can be manually advanced via Robolectric APIs.
- Robolectric will warn users if a test fails with unexecuted tasks in the main Looper queue
- Robolectric test APIs, like
ActivityController.setup(), will automatically idle the main
Looperhas its own thread. Tasks posted to background loopers are executed asynchronously in separate threads.
Looperuse the real
MessageQueueto store their queue of pending tasks
- There is only a single clock value, managed via
ShadowSystemClock. This can be explictly incremented via
SchedulerAPIs for the 'foreground' scheduler are currently supported in this mode as well, although it is recommended to switch to use ShadowLooper APIs directly.
- Apply the LooperMode(PAUSED) annotation to your test package/class/method (or remove a LooperMode(LEGACY) annotation)
- Convert any background
Loopers to shadowOf(looper)
- Convert any
- Run your tests. If you see an test failures like 'Main looper has queued unexecuted runnables.', you may need to insert shadowOf(getMainLooper()).idle() calls to your test to drain the main Looper.
INSTRUMENTATION_TESTpublic static final LooperMode.Mode INSTRUMENTATION_TESTA mode that simulates an android instrumentation test threading model, which has a separate test thread distinct from the main looper thread.
Otherwise it is quite similar to PAUSED mode. The clock time is still fixed, and you can use shadowLooper methods to pause, unpause, and wait for any looper to be idle.
It is recommended to use this mode in tests that mostly use androidx.test APIs, which will support being called directly on the main thread or on the test thread. Most org.robolectric APIs that interact with the android UI (e.g. ActivityController) will raise an exception if called off the main thread.
valuespublic static LooperMode.Mode values()Returns an array containing the constants of this enum type, in the order they are declared.
- an array containing the constants of this enum type, in the order they are declared
valueOfReturns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)