A collection of JUnit Rules that can be helpful to Android Developers. Do you have any idea for a JUnit rule that could be helpful for everyone? Feel free to open an Issue or a Pull request!

This repo contains the source code related to this article: Don't be lazy, use @Rules.

rules4android is distributed through JCenter. To use it you need to add the following Gradle dependency to your android app gradle file (NOT the root file).

dependencies { testImplementation 'com.ncorti:rules4android:1.0.0' }

or if you need it from your Espresso tests:

dependencies { androidTestImplementation 'com.ncorti:rules4android:1.0.0' }

You can use a RetryRule to retry tests that might be flaky, just by annotating them with a @RetryOnFailure. By default, annotated tests are retried other 2 times. You can specify the retry count in the annotation. If the test fails more than 1 + retryCount times, a message will be printed out on the console.

Example:

class ExampleTest { @get:Rule val rule = RetryRule() @Test @RetryOnFailure(10) // 10 can be omitted, will default to 2. fun aFlakyTest() { assertEquals(2, Math.random().toInt()) } }

More examples can be found in the RetryRuleTest.kt file.

You can use a LoggingRule to print out the execution time of every test. If you need more structured data for further processing of your tests, you can pass a flag to the Rule to enable the CSV output.

Example:

class ExampleTest { @get:Rule val rule = TimingRule(printCsv = false) @Test fun aLongTest() { Thread.sleep(1000) assertEquals(42, 42) } }

Will print on the console:

ExampleTest:aLongTest took 1001 ms 

More examples can be found in the LoggingRuleTest.kt file.

You can use a LocaleRule to change locale of the device/JVM. The rule has support for both JUnit and Espresso tests. You can either pass a locale via the @ChangeLocale annotation, or via a parameter in the Rule constructor.

Example:

class ExampleTest { @get:Rule val rule = LocaleRule(Locale.ITALIAN) @Test fun anItalianTest() { // Locale Changed by constructor parameter. assertEquals("it", Locale.getDefault().language) } @Test @ChangeLocale("de") fun aGermanTest() { // Locale Changed by annotation. assertEquals("de", Locale.getDefault().language) } }

More examples can be found in the LocaleRuleTest.kt file.

Looking for contributors! Don't be shy. 😁 Feel free to open issues/pull requests to help me improve this project.

This project is licensed under the MIT License - see the License file for details