Android provides a testing framework for Service objects that can run them in
isolation and provides mock objects. The test case class for Service objects is
ServiceTestCase. Since the Service class assumes that it is separate
from its clients, you can test a Service object without using instrumentation.
This document describes techniques for testing Service objects. If you aren't familiar with the Service class, please read the Services document. If you aren't familiar with Android testing, please read Testing Fundamentals, the introduction to the Android testing and instrumentation framework.
Service Design and Testing
When you design a Service, you should consider how your tests can examine the various states
of the Service lifecycle. If the lifecycle methods that start up your Service, such as
onStartCommand() do not normally
set a global variable to indicate that they were successful, you may want to provide such a
variable for testing purposes.
Most other testing is facilitated by the methods in the
test case class. For example, the
returns a handle to the Service under test, which you can test to confirm that the Service is
running even at the end of your tests.
ServiceTestCase extends the JUnit
with methods for testing application permissions and for controlling the application and
Service under test. It also provides mock application and Context objects that isolate your
test from the rest of the system.
ServiceTestCase defers initialization of the test environment until you
allows you to set up your test environment, particularly your mock objects, before the Service
Notice that the parameters to
ServiceTestCase.bindService()are different from
Service.bindService(). For the
you only provide an Intent. Instead of returning a boolean,
ServiceTestCase.bindService() returns an object that subclasses
setUp() method for
is called before each test. It sets up the test fixture by making a copy of the current system
Context before any test methods touch it. You can retrieve this Context by calling
getSystemContext(). If you override this method, you must
super.setUp() as the first statement in the override.
setContext(Context) setContext()} allow you to set
a mock Context or mock Application (or both) for the Service, before you start it. These mock
objects are described in Mock object classes.
Mock object classes
ServiceTestCase assumes that you will use a mock Context or mock Application
(or both) for the test environment. These objects isolate the test environment from the
rest of the system. If you don't provide your own instances of these objects before you
start the Service, then
ServiceTestCase will create its own internal
instances and inject them into the Service. You can override this behavior by creating and
injecting your own instances before starting the Service
To inject a mock Application object into the Service under test, first create a subclass of
MockApplication is a subclass of
Application in which all the methods throw an Exception, so to use it
effectively you subclass it and override the methods you need. You then inject it into the
Service with the
This mock object allows you to control the application values that the Service sees, and
isolates it from the real system. In addition, any hidden dependencies your Service has on
its application reveal themselves as exceptions when you run the test.
What to Test
The topic What To Test lists general considerations for testing Android components. Here are some specific guidelines for testing a Service:
Ensure that the
onCreate()is called in response to
Context.bindService(). Similarly, you should ensure that
onDestroy()is called in response to
Test that your Service correctly handles multiple calls from
Context.startService(). Only the first call triggers
Service.onCreate(), but all calls trigger a call to
In addition, remember that
startService()calls don't nest, so a single call to
stopSelf(int)) will stop the Service. You should test that your Service stops at the correct point.
- Test any business logic that your Service implements. Business logic includes checking for invalid values, financial and arithmetic calculations, and so forth.