The
AndroidJUnitRunner
class is a
JUnit
test runner that
lets you run instrumented
JUnit 4
tests on Android devices,
including those using the
Espresso
,
UI Automator
, and
Compose
testing frameworks.
The test runner handles loading your test package and the app under test to a
device, running your tests, and reporting test results.
This test runner supports several common testing tasks, including the following:
Write JUnit tests
The following code snippet shows how you might write an instrumented JUnit 4
test to validate that the
changeText
operation in the
ChangeTextBehavior
class works correctly:
Kotlin
@RunWith(AndroidJUnit4::class) // Only needed when mixing JUnit 3 and 4 tests
@LargeTest // Optional runner annotation
class ChangeTextBehaviorTest {
val stringToBeTyped = "Espresso"
// ActivityTestRule accesses context through the runner
@get:Rule
val activityRule = ActivityTestRule(MainActivity::class.java)
@Test fun changeText_sameActivity() {
// Type text and then press the button.
onView(withId(R.id.editTextUserInput))
.perform(typeText(stringToBeTyped), closeSoftKeyboard())
onView(withId(R.id.changeTextBt)).perform(click())
// Check that the text was changed.
onView(withId(R.id.textToBeChanged))
.check(matches(withText(stringToBeTyped)))
}
}
Java
@RunWith(AndroidJUnit4.class) // Only needed when mixing JUnit 3 and 4 tests
@LargeTest // Optional runner annotation
public class ChangeTextBehaviorTest {
private static final String stringToBeTyped = "Espresso";
@Rule
public ActivityTestRule<MainActivity>; activityRule =
new ActivityTestRule<>;(MainActivity.class);
@Test
public void changeText_sameActivity() {
// Type text and then press the button.
onView(withId(R.id.editTextUserInput))
.perform(typeText(stringToBeTyped), closeSoftKeyboard());
onView(withId(R.id.changeTextBt)).perform(click());
// Check that the text was changed.
onView(withId(R.id.textToBeChanged))
.check(matches(withText(stringToBeTyped)));
}
}
Access the Application's Context
When you use
AndroidJUnitRunner
to run your tests, you can access the context
for the app under test by calling the static
ApplicationProvider.getApplicationContext()
method. If you've created a custom
subclass of
Application
in your app, this method returns your custom
subclass's context.
If you're a tools implementer, you can access low-level testing APIs using the
InstrumentationRegistry
class. This class includes the
Instrumentation
object, the target app
Context
object, the test
app
Context
object, and the command line arguments passed into your test.
Filter tests
In your JUnit 4.x tests, you can use annotations to configure the test run. This
feature minimizes the need to add boilerplate and conditional code in your
tests. In addition to the standard annotations supported by JUnit 4, the test
runner also supports
Android-specific annotations
, including the
following:
@RequiresDevice
: Specifies that the test should run only on physical
devices, not on emulators.
@SdkSuppress
: Suppresses the test from running on a lower Android API
level
than the given level. For example, to suppress tests on all API levels lower
than 23 from running, use the annotation
@SDKSuppress(minSdkVersion=23)
.
@SmallTest
,
@MediumTest
, and
@LargeTest
: Classify how long a test
should take to run, and consequently, how frequently you can run the test. You
can use this annotation to filter which tests to run, setting the
android.testInstrumentationRunnerArguments.size
property:
-Pandroid.testInstrumentationRunnerArguments.size=small
Shard tests
If you need to parallelize the execution of your tests, sharing them across
multiple servers to make them run faster, you can split them into groups, or
shards
. The test runner supports splitting a single test suite into multiple
shards, so you can easily run tests belonging to the same shard together as a
group. Each shard is identified by an index number. When running tests, use the
-e numShards
option to specify the number of separate shards to create and the
-e shardIndex
option to specify which shard to run.
For example, to split the test suite into 10 shards and run only the tests
grouped in the second shard, use the following
adb command
:
adb shell am instrument -w -e numShards 10 -e shardIndex 2
Use Android Test Orchestrator
Android Test Orchestrator allows you to run each of your app's tests within its
own invocation of
Instrumentation
. When using AndroidJUnitRunner version 1.0
or higher, you have access to Android Test Orchestrator.
Android Test Orchestrator offers the following benefits for your testing
environment:
- Minimal shared state:
Each test runs in its own
Instrumentation
instance. Therefore, if your tests share app state, most of that shared state
is removed from your device's CPU or memory after each test.
To remove
all
shared state from your device's CPU and memory after each
test, use the
clearPackageData
flag. See the
Enable from Gradle
section for an example.
- Crashes are isolated:
Even if one test crashes, it takes down only its
own instance of
Instrumentation
. This means that the other tests in
your suite still run, providing complete test results.
This isolation results in a possible increase in test execution time as the
Android Test Orchestrator restarts the application after each test.
Both Android Studio and Firebase Test Lab have Android Test Orchestrator
pre-installed, though you need to
enable the feature in Android
Studio
.
Enable from Gradle
To enable Android Test Orchestrator using the Gradle command-line tool, complete
these steps:
- Step 1
: Modify gradle file. Add the following statements to your
project's
build.gradle
file:
android {
defaultConfig {
...
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
// The following argument makes the Android Test Orchestrator run its
// "pm clear" command after each test invocation. This command ensures
// that the app's state is completely cleared between tests.
testInstrumentationRunnerArguments clearPackageData: 'true'
}
testOptions {
execution 'ANDROIDX_TEST_ORCHESTRATOR'
}
}
dependencies {
androidTestImplementation 'androidx.test:runner:1.1.0'
androidTestUtil 'androidx.test:orchestrator:1.1.0'
}
- Step 2
: Run Android Test Orchestrator by executing the following command:
./gradlew connectedCheck
Enable from Android Studio
To enable Android Test Orchestrator in Android Studio, add the statements shown
in
Enable from Gradle
to your app's
build.gradle
file.
Enable from command line
To use Android Test Orchestrator on the command line, run the following commands
in a terminal window:
DEVICE_API_LEVEL=$(adb shell getprop ro.build.version.sdk)
FORCE_QUERYABLE_OPTION=""
if [[ $DEVICE_API_LEVEL -ge 30 ]]; then
FORCE_QUERYABLE_OPTION="--force-queryable"
fi
# uninstall old versions
adb uninstall androidx.test.services
adb uninstall androidx.test.orchestrator
# Install the test orchestrator.
adb install $FORCE_QUERYABLE_OPTION -r path/to/m2repository/androidx/test/orchestrator/1.4.2/orchestrator-1.4.2.apk
# Install test services.
adb install $FORCE_QUERYABLE_OPTION -r path/to/m2repository/androidx/test/services/test-services/1.4.2/test-services-1.4.2.apk
# Replace "com.example.test" with the name of the package containing your tests.
# Add "-e clearPackageData true" to clear your app's data in between runs.
adb shell 'CLASSPATH=$(pm path androidx.test.services) app_process / \
androidx.test.services.shellexecutor.ShellMain am instrument -w -e \
targetInstrumentation com.example.test/androidx.test.runner.AndroidJUnitRunner \
androidx.test.orchestrator/.AndroidTestOrchestrator'
As the command syntax shows, you install Android Test Orchestrator, then use it
directly.
adb shell pm list instrumentation
Using different toolchains
If you use a different toolchain to test your app, you can still use Android
Test Orchestrator by completing the following steps:
- Include the necessary
packages
in your app's build file.
- Enable Android Test Orchestrator
from the command-line
.
Architecture
The Orchestrator service APK is stored in a process that's separate from the
test APK and the APK of the app under test:
Android Test Orchestrator collects JUnit tests at the beginning of your test
suite run, but it then executes each test separately, in its own instance of
Instrumentation
.
To learn more about using AndroidJUnitRunner, see the
API reference
.
Additional resources
For more information about using
AndroidJUnitRunner
, consult the following
resources.
Samples