If you are new to Android platform development, you might find this complete example of adding a brand new instrumentation test from scratch useful to demonstrate the typical workflow involved.
Note that this guide assumes that you already have some knowledge in the platform source tree workflow. If not, please refer to https://source.android.com/source/requirements. The example covered here is writing an new instrumentation test with target package set at its own test application package. If you are unfamiliar with the concept, please read through the testing basics page.
This guide uses the follow test to serve as an sample:
It's recommended to browse through the code first to get a rough impression before proceeding.
Because the instrumentation test will be targeting an application, the convention is to place the test source code in a tests directory under the root of your component source directory in platform source tree.
See more discussions about source location in the end-to-end example for self-instrumenting tests.
Each new test module must have a makefile to direct the build system with module metadata, compile time depdencies and packaging instructions.
frameworks/base/packages/Shell/tests/Android.mk
A snapshot is included here for convenience:
LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE_TAGS := tests LOCAL_SRC_FILES := $(call all-java-files-under, src) LOCAL_JAVA_LIBRARIES := android.test.runner LOCAL_STATIC_JAVA_LIBRARIES := ub-uiautomator junit legacy-android-test LOCAL_PACKAGE_NAME := ShellTests LOCAL_INSTRUMENTATION_FOR := Shell LOCAL_COMPATIBILITY_SUITE := device-tests LOCAL_CERTIFICATE := platform include $(BUILD_PACKAGE)
Some select remarks on the makefile:
LOCAL_MODULE_TAGS := tests
This setting declares the module as a test module, which will instruct the build system to automatically skip proguard stripping, since that's typically problematic for tests.
LOCAL_CERTIFICATE := platform
This setting instructs the build system to sign the test application package with the platform certificate. This is because for a test application package to be able to instrument on the targeted application package, these two packages must be signed with the same certificate; otherwise allowing packages to be instrumented on arbitrarily would be a security concern. To find out the signing certificate of the application packge you are testing, look for LOCAL_CERTIFICATE in its Android.mk; and if there isn't one, simply skip this field in your test application makefile as well.
LOCAL_JAVA_LIBRARIES := android.test.runner
This setting tells the build system to put Java library android.test.runner on classpath during compilation, as opposed to statically incorporating the library into the current package. This is typically done for Java code that is referenced by the code in current package, and will be automatically placed on package classpath at runtime. In the context of tests for application, strictly speaking, both framework APIs and code in application under test fall into this category, however, the former is done via implicit rules by build system at compile time and by framework at runtime, and the latter is done via LOCAL_INSTRUMENTATION_FOR (see below) at compile time and via android:targetPackage (see below) in manifest by instrumentation framework at runtime.
LOCAL_STATIC_JAVA_LIBRARIES := ub-uiautomator junit legacy-android-test
This setting instructs the build system to incorporate the contents of the named modules into the resulting apk of current module. This means that each named module is expected to produce a .jar file, and its content will be used for resolving classpath references during compile time, as well as incorporated into the resulting apk.
The platform source tree also included other useful testing frameworks such as ub-uiautomator, easymock and so on.
LOCAL_PACKAGE_NAME := ShellTests
This setting is required if BUILD_PACKAGE when used later: it gives a name to your module, and the resulting apk will be named the same and with a .apk suffix, e.g. in this case, resulting test apk is named as ShellTests.apk. In addition, this also defines a make target name for your module, so that you can use make [options] <LOCAL_PACKAGE_NAME> to build your test module and all its dependencies.
LOCAL_INSTRUMENTATION_FOR := Shell
As mentioned, during execution of an instrumentation test, the application under test is restarted with the instrumentation code injected for execution. The test can reference any classes and its instances of the application under test. This means that the test code may contain references to classes defined by the application under test, so during compile time, the build system needs to properly resolve such references. This setting provides the module name of application under test, which should match the LOCAL_PACKAGE_NAME of in the makefile for your application. At compile time, the build system will try to look up the intermediate files for the named module, and use them on the classpath for the Java compiler.
LOCAL_COMPATIBILITY_SUITE := device-tests
This line builds the testcase as part of the device-tests suite, which is meant to target a specific device and not a general ABI. If only the ABI needs to be targetted, it can be swapped with ‘general-tests’.
include $(BUILD_PACKAGE)
This includes a core makefile in build system that performs the necessary steps to generate an apk based on the settings provided by the preceding variables. The generated apk will be named after LOCAL_PACKAGE_NAME, e.g. SettingsGoogleUnitTests.apk. And if tests is used as LOCAL_MODULE_TAGS and there are no other customizations, you should be able to find your test apk in:
${OUT}/data/app/<LOCAL_PACKAGE_NAME>/<LOCAL_PACKAGE_NAME>.apke.g. ${OUT}/data/app/ShellTests/ShellTests.apk
Just like a regular application, each instrumentation test module needs a manifest file. If you name the file as AndroidManifest.xml and provide it next to Android.mk for your test tmodule, it will get included automatically by the BUILD_PACKAGE core makefile.
Before proceeding further, it's highly recommended to go through the external documentation on manifest file first.
This gives an overview of basic components of a manifest file and their functionalities.
Latest version of the manifest file for the sample gerrit change can be accessed at: https://android.googlesource.com/platform/frameworks/base/+/master/packages/Shell/tests/AndroidManifest.xml
A snapshot is included here for convenience:
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.android.shell.tests"> <application> <uses-library android:name="android.test.runner" /> <activity android:name="com.android.shell.ActionSendMultipleConsumerActivity" android:label="ActionSendMultipleConsumer" android:theme="@android:style/Theme.NoDisplay" android:noHistory="true" android:excludeFromRecents="true"> <intent-filter> <action android:name="android.intent.action.SEND_MULTIPLE" /> <category android:name="android.intent.category.DEFAULT" /> <data android:mimeType="*/*" /> </intent-filter> </activity> </application> <instrumentation android:name="android.support.test.runner.AndroidJUnitRunner" android:targetPackage="com.android.shell" android:label="Tests for Shell" /> </manifest>
Some select remarks on the manifest file:
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.android.shell.tests">
The package attribute is the application package name: this is the unique identifier that the Android application framework uses to identify an application (or in this context: your test application). Each user in the system can only install one application with that package name.
Since this is a test application package, independent from the application package under test, a different package name must be used: one common convention is to add a suffix .test.
Furthermore, this package attribute is the same as what ComponentName#getPackageName() returns, and also the same you would use to interact with various pm sub commands via adb shell.
Please also note that although the package name is typically in the same style as a Java package name, it actually has very few things to do with it. In other words, your application (or test) package may contain classes with any package names, though on the other hand, you could opt for simplicity and have your top level Java package name in your application or test identical to the application package name.
<uses-library android:name="android.test.runner" />
This is required for all Instrumentation tests since the related classes are packaged in a separate framework jar library file, therefore requires additional classpath entries when the test package is invoked by application framework.
android:targetPackage="com.android.shell"
This sets the target package of the instrumentation to com.android.shell.tests. When the instrumentation is invoked via am instrument command, the framework restarts com.android.shell.tests process, and injects instrumentation code into the process for test execution. This also means that the test code will have access to all the class instances running in the application under test and may be able to manipulate state depends on the test hooks exposed.
In order to simplify test execution, you also need write a test configuration file for Android's test harness, TradeFederation.
The test configuration can specify special device setup options and default arguments to supply the test class.
The config can be found: frameworks/base/packages/Shell/tests/src/com/android/shell/BugreportReceiverTest.javast.java
A snapshot is included here for convenience:
<configuration description="Runs Tests for Shell."> <target_preparer class="com.android.tradefed.targetprep.TestAppInstallSetup"> <option name="test-file-name" value="ShellTests.apk" /> </target_preparer> <option name="test-suite-tag" value="apct" /> <option name="test-tag" value="ShellTests" /> <test class="com.android.tradefed.testtype.AndroidJUnitTest" > <option name="package" value="com.android.shell.tests" /> <option name="runner" value="android.support.test.runner.AndroidJUnitRunner" /> </test> </configuration>
Some select remarks on the test configuration file:
<target_preparer class="com.android.tradefed.targetprep.TestAppInstallSetup"> <option name="test-file-name" value="ShellTests.apk"/> </target_preparer>
This tells TradeFederation to install the ShellTests.apk onto the target device using a specified target_preparer. There are many target preparers available to developers in TradeFederation and these can be used to ensure the device is setup properly prior to test execution.
<test class="com.android.tradefed.testtype.AndroidJUnitTest"> <option name="package" value="com.android.shell.tests"/> <option name="runner" value="android.support.test.runner.AndroidJUnitRunner"/> </test>
This specifies the TradeFederation test class to use to execute the test and passes in the package on the device to be executed and the test runner framework which is JUnit in this case.
Look here for more information on Test Module Configs
Using android-support-test library as test runner enables adoptation of new JUnit4 style test classes, and the sample gerrit change contains some very basic use of its features.
Latest source code for the sample gerrit change can be accessed at: frameworks/base/packages/Shell/tests/src/com/android/shell/BugreportReceiverTest.javast.java
While testing patterns are usually specific to component teams, there are some generally useful usage patterns.
@SmallTest @RunWith(AndroidJUnit4.class) public final class FeatureFactoryImplTest {
A significant difference in JUnit4 is that tests are no longer required to inherit from a common base test class; instead, you write tests in plain Java classes and use annotation to indicate certain test setup and constraints. In this example, we are instructing that this class should be run as an Android JUnit4 test.
The @SmallTest annotation specified a test size for the entire test class: all test methods added into this test class inherit this test size annotation. pre test class setup, post test tear down, and post test class tear down: similar to setUp and tearDown methods in JUnit4. Test annotation is used for annotating the actual test.
Important: the test methods themselves are annotated with @Test annotation; and note that for tests to be executed via APCT, they must be annotated with test sizes. Such annotation may be applied at method scope, or class scope.
@Before public void setup() { ... @Test public void testGetProvider_shouldCacheProvider() { ...
The @Before annotation is used on methods by JUnit4 to perform pre test setup. Although not used in this example, there's also @After for post test teardown. Similarly, the @BeforeClass and @AfterClass annotations are can be used on methods by JUnit4 to perform setup before executing all tests in a test class, and teardown afterwards. Note that the class-scope setup and teardown methods must be static.
As for the test methods, unlike in earlier version of JUnit, they no longer need to start the method name with test, instead, each of them must be annotated with @Test. As usual, test methods must be public, declare no return value, take no parameters, and may throw exceptions.
Context context = InstrumentationRegistry.getTargetContext();
Because the JUnit4 tests no longer require a common base class, it's no longer necessary to obtain Context instances via getContext() or getTargetContext() via base class methods; instead, the new test runner manages them via InstrumentationRegistry where contextual and environmental setup created by instrumentation framework is stored. Through this class, you can also call:
getInstrumentation(): the instance to the Instrumentation classgetArguments(): the command line arguments passed to am instrument via -e <key> <value>Follow these Instructions