Junit 5 – repeated tests

In this article we will see how Junit 5 repeated tests works, how to use @RepeatedTest, RepetitionInfo in writing test cases, display custom names in writing repeated tests, how test methods execution order works with repeated tests and how to create a custom annotation using repeated tests with several examples.

1. Junit 5 repeated tests

@RepeatedTest is used to signal that the annotated method is a test template method that should be repeated a specified number of times with a configurable display name.

1.1. @RepeatedTest example

The @RepeatedTest test method is just like a regular @Test method, the same life cycle. @RepeatedTest methods must not be private or static and must return void.

public class Junit5_RepeatedTest_Test {
	
	@RepeatedTest(1)
	static void test_Add() {
		System.out.println("test_Add()");
		assertEquals(5, MathUtil.add(3, 2));
	}
	
	@Test
	void test_Multiply() {
		System.out.println("test_Multiply()");
		assertEquals(15, MathUtil.multiple(3, 5));
	}

	@RepeatedTest(3)
	void test_Devide() {
		System.out.println("test_Devide()");
		assertEquals(5, MathUtil.devide(25, 5));
	}
	
	@RepeatedTest(2)
	void test_IsPrime() {
		System.out.println("test_IsPrime()");
		assertTrue(MathUtil.isPrime(13));
	}
}

Output :

test_IsPrime()
test_IsPrime()
test_Devide()
test_Devide()
test_Devide()
test_Multiply()

1.2. @RepeatedTest custom test name example

We can configure the custom name of the @RepeatedTest method. Following are the place holders can be used to display custom names for Repeated tests Or we can use RepeatedTest.LONG_DISPLAY_NAME or RepeatedTest.LONG_DISPLAY_NAME.

1. {displayName}: Name of the test method.
2. {currentRepetition}: The current repetition count.
3. {totalRepetitions}: The total number of repetitions.

@DisplayNameGeneration(DisplayNameGenerator.ReplaceUnderscores.class)
public class Junit5_RepeatedTest_CustomDisplayName_Test {
	
	@Test
	void test_Add() {
		System.out.println("test_Add()");
		assertEquals(5, MathUtil.add(3, 2));
	}
	
	@RepeatedTest(value = 1, name = RepeatedTest.SHORT_DISPLAY_NAME)
	void test_Multiply() {
		System.out.println("test_Multiply()");
		assertEquals(15, MathUtil.multiple(3, 5));
	}

	@RepeatedTest(value = 3, name = "{displayName} - {currentRepetition}/{totalRepetitions}")
	void test_Devide() {
		System.out.println("test_Devide()");
		assertEquals(5, MathUtil.devide(25, 5));
	}
	
	@RepeatedTest(value = 2, name = RepeatedTest.LONG_DISPLAY_NAME)
	void test_IsPrime() {
		System.out.println("test_IsPrime()");
		assertTrue(MathUtil.isPrime(13));
	}
}

Results in Eclipse :

2. Injecting RepetitionInfo with example

1. RepetitionInfo is used to inject information about the current repetition of a repeated test into @RepeatedTest, @BeforeEach, @AfterEach methods.
2. If a method parameter is of type RepetitionInfo, JUnit will supply an instance of RepetitionInfo corresponding to the current repeated test as the value for the parameter.
3. RepetitionInfo cannot be injected into a @BeforeEach or @AfterEach method if the corresponding test method is not a @RepeatedTest.

@DisplayNameGeneration(DisplayNameGenerator.ReplaceUnderscores.class)
public class Junit5_RepeatedTest_RepetitionInfo_Test {
	
	@BeforeEach
    void beforeEach(TestInfo testInfo, RepetitionInfo repetitionInfo) {
        int currentRepetition = repetitionInfo.getCurrentRepetition();
        int totalRepetitions = repetitionInfo.getTotalRepetitions();
        String methodName = testInfo.getTestMethod().get().getName();
        
        System.out.println(String.format("About to execute repetition %d of %d for %s", //
                currentRepetition, totalRepetitions, methodName));
    }
	
	@Test
	void test_Add(RepetitionInfo repetitionInfo) {
		System.out.println("test_Add()");
		assertEquals(5, MathUtil.add(3, 2));
	}
	
	@RepeatedTest(1)
	void test_Multiply() {
		System.out.println("test_Multiply()");
		assertEquals(15, MathUtil.multiple(3, 5));
	}

	@RepeatedTest(3)
	void test_Devide() {
		System.out.println("test_Devide()");
		assertEquals(5, MathUtil.devide(25, 5));
	}
	
	@RepeatedTest(2)
	void test_IsPrime(RepetitionInfo repetitionInfo) {
		assertEquals(2, repetitionInfo.getTotalRepetitions());
		System.out.println("test_IsPrime()");
		assertTrue(MathUtil.isPrime(13));
	}
}

Output :

About to execute repetition 1 of 2 for test_IsPrime
test_IsPrime()
About to execute repetition 2 of 2 for test_IsPrime
test_IsPrime()
About to execute repetition 1 of 3 for test_Devide
test_Devide()
About to execute repetition 2 of 3 for test_Devide
test_Devide()
About to execute repetition 3 of 3 for test_Devide
test_Devide()
About to execute repetition 1 of 1 for test_Multiply
test_Multiply()

Results in Eclipse

3. Repeated tests method execution order

By default test methods order not defined, but Junit 5 algorithm ensures same method order for the subsequent tests runs by default. To control the order annotate your test class with @TestMethodOrder.

@TestMethodOrder(Alphanumeric.class)
public class Junit5_RepeatedTest_MethodOrder_Test {
	
	@RepeatedTest(1)
	static void test_Add() {
		System.out.println("test_Add()");
		assertEquals(5, MathUtil.add(3, 2));
	}
	
	@Test
	void test_Multiply() {
		System.out.println("test_Multiply()");
		assertEquals(15, MathUtil.multiple(3, 5));
	}

	@RepeatedTest(3)
	void test_Devide() {
		System.out.println("test_Devide()");
		assertEquals(5, MathUtil.devide(25, 5));
	}
	
	@RepeatedTest(2)
	void test_IsPrime() {
		System.out.println("test_IsPrime()");
		assertTrue(MathUtil.isPrime(13));
	}
}

Output :

test_Devide()
test_Devide()
test_Devide()
test_IsPrime()
test_IsPrime()
test_Multiply()

4. Create Custom RepeatedTest annotation

If we are using same number of repetitions, Junit 5 supports to create a custom annotation for repeated test annotation.

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@RepeatedTest(value = 3, name = "{displayName} - {currentRepetition}/{totalRepetitions}")
public @interface MyRepeatedTest {

}

public class Junit5_RepeatedTest_CustomAnnotation_Test {
	
	@MyRepeatedTest
	static void test_Add() {
		System.out.println("test_Add()");
		assertEquals(5, MathUtil.add(3, 2));
	}
	
	@MyRepeatedTest
	void test_Multiply() {
		System.out.println("test_Multiply()");
		assertEquals(15, MathUtil.multiple(3, 5));
	}

	@MyRepeatedTest
	void test_Devide() {
		System.out.println("test_Devide()");
		assertEquals(5, MathUtil.devide(25, 5));
	}
	
	@MyRepeatedTest
	void test_IsPrime() {
		System.out.println("test_IsPrime()");
		assertTrue(MathUtil.isPrime(13));
	}
}

Output :

test_IsPrime()
test_IsPrime()
test_IsPrime()
test_Devide()
test_Devide()
test_Devide()
test_Multiply()
test_Multiply()
test_Multiply()

Conclusion

In this article we have seen how Junit 5 repeated tests works, how to use @RepeatedTest, RepetitionInfo in writing test cases, display custom names in writing repeated tests, how test methods execution order works with repeated tests and how to create a custom annotation using repeated tests with several examples.

You also might be interested in following examples :

1. Junit 5 Dynamic Tests
2. Junit 5 tags and filter test cases
3. Junit 5 Timeout tests
4. Junit 5 test order
5. Junit 5 parameterized tests
6. Junit 5 Parameter Resolvers