Unit tests

Here’s a few handy commands if you want to run only a specific unit test(s). Suppose we have the following unit tests in the project:

./gradlew test – run unit tests for all variants
./gradlew testDebug – run tests for Debug variant
./gradlew testDebug --tests="*.helpers.*" – run all tests in the helpers package
./gradlew testDebug --tests="*.HelperTest" – run all tests in HelperTest.java class
./gradlew testDebug --tests="*.getHelp" – run only the getHelp test method.

Instrumentation tests

Running instrumentation tests is a bit different than unit tests. If you just want to run a single instrumentation test class you can use:

./gradlew -Pandroid.testInstrumentationRunnerArguments.class=com.example.TestClass connectedDebugAndroidTest

Or if you want to run just 1 single test method within the class:

./gradlew -Pandroid.testInstrumentationRunnerArguments.class=com.example.TestClass#testMethod connectedDebugAndroidTest

There also another, more versatile way to run instrumentation tests from the console:

./gradlew installDebugAndroidTest – install the app and tests

adb shell am instrument -w -e class com.example.MyInstrumentationTest#testFoo com.example.test/android.support.test.runner.AndroidJUnitRunner

The instrument command supports a lot of options that give you fine-grained control over what and how it’s ran. For a full list of them check the official Android documentation HERE.

Bonus – printing unit test results to the console

It’s really useful to see why a unit test is failing directly in the console output like this:

To do so we need a bit of Gradle magic:

android {
	...

	testOptions {
        unitTests.all {
            testLogging {
                events "passed", "failed", "standardError"
                showCauses true
                showExceptions true
            }
        }
    } 
}

Adding this to your build.gradle will output the result of every test (passed / failed), or any errors that have occurred. Documentation for the testLogging task, including all possible options can be found HERE.

One thing to mention here – by default Gradle will cache results of every task and won’t execute it again if there’s no changes (thus you see a lot of “UP-TO-DATE” when you run a subsequent build). This applies to the test task as well, so running it twice in a row won’t run your unit tests twice if the first time is successful and you don’t perform a clean in between.

If you want to overwrite the specific behaviour you can force the tests to be run every time by adding outputs.upToDateWhen {false} to any task that’s part of the test chain. Since you already have a testLogging one in place, you can just put it there:

android {
	...

	testOptions {
        unitTests.all {
            testLogging {
                outputs.upToDateWhen {false}
                events "passed", "failed", "standardError"
                showCauses true
                showExceptions true
            }
        }
    } 
}

Lastly it’s worth mentioning that if you have more specific needs in regards to running multiple test suites and configurations, it’s probably a good idea to take a look at Square’s Spoon or Shazam’s Fork libraries.

Happy testing!