JUnit 5 @RepeatedTest

The @RepeatedTest annotation is used to write repeatable test templates that could run multiple times in JUnit. The repetition frequency can be configured as a parameter to @RepeatedTest annotation.

1. @RepeatedTest Annotation

The @RepeatedTest annotation is used to mark a test method that should repeat a specified number of times with a configurable display name.

To repeat a test with different arguments, consider using @ParameterizedTest.

1.1. Syntax

To create a repeatable test, annotate the test method with @RepeatedTest.

In the given example, the test method uses @RepeatedTest(5) annotation. It means that the test will be executed five times.

@DisplayName("Add operation test") @RepeatedTest(5) void addNumber(TestInfo testInfo) {	Calculator calculator = new Calculator();	Assertions.assertEquals(2, calculator.add(1, 1), "1 + 1 should equal 2"); }

1.2. Lifecycle Methods

Please note that each invocation of a repeated test behaves like the execution of a regular test with full support for the same lifecycle callbacks and extensions.

It means that @BeforeEach and @AfterEach annotated lifecycle methods will be invoked for each invocation of the test.

package com.howtodoinjava.junit5.examples; import org.junit.jupiter.api.AfterAll; import org.junit.jupiter.api.AfterEach; import org.junit.jupiter.api.Assertions; import org.junit.jupiter.api.BeforeAll; import org.junit.jupiter.api.BeforeEach; import org.junit.jupiter.api.DisplayName; import org.junit.jupiter.api.RepeatedTest; import org.junit.jupiter.api.RepetitionInfo; import org.junit.jupiter.api.Test; import org.junit.jupiter.api.TestInfo; import org.junit.platform.runner.JUnitPlatform; import org.junit.runner.RunWith; @RunWith(JUnitPlatform.class) public class RepeatedTestExample {	@BeforeAll	public static void init(){	System.out.println("Before All init() method called");	}	@BeforeEach	public void initEach(){	System.out.println("Before Each initEach() method called");	}	@DisplayName("Add operation test")	@RepeatedTest(5)	void addNumber(TestInfo testInfo, RepetitionInfo repetitionInfo)	{	System.out.println("Running addNumber test -> " + repetitionInfo.getCurrentRepetition());	Assertions.assertEquals(2, Calculator.add(1, 1), "1 + 1 should equal 2");	}	@AfterEach	public void cleanUpEach(){	System.out.println("After Each cleanUpEach() method called");	}	@AfterAll	public static void cleanUp(){	System.out.println("After All cleanUp() method called");	} }

The output of the above test:

Before All init() method called Before Each initEach() method called After Each cleanUpEach() method called Before Each initEach() method called Running addNumber test -> 1 After Each cleanUpEach() method called Before Each initEach() method called Running addNumber test -> 2 After Each cleanUpEach() method called Before Each initEach() method called Running addNumber test -> 3 After Each cleanUpEach() method called Before Each initEach() method called Running addNumber test -> 4 After Each cleanUpEach() method called Before Each initEach() method called Running addNumber test -> 5 After Each cleanUpEach() method called After All cleanUp() method called 

2. Custom Display Names

Apart from specifying the number of repetitions, we can give a custom display name to each repetition. This custom display name can be a combination of {static text + dynamic placeholders}.

Currently, three placeholders are supported:

• {displayName}: display name of the @RepeatedTest method.
• {currentRepetition}: the current repetition count.
• {totalRepetitions}: the total number of repetitions.

public class JUnit5AnnotationsExample {	@DisplayName("Add operation test")	@RepeatedTest(value = 5, name = "{displayName} - repetition {currentRepetition} of {totalRepetitions}")	void addNumber(TestInfo testInfo) {	Assertions.assertEquals(2, Calculator.add(1, 1), "1 + 1 should equal 2");	} }

Running the above test will output in below:

We can use one of two predefined formats i.e. LONG_DISPLAY_NAME and SHORT_DISPLAY_NAME. The latter is the default format if none is specified.

• RepeatedTest.LONG_DISPLAY_NAME – {displayName} :: repetition {currentRepetition} of {totalRepetitions}
• RepeatedTest.SHORT_DISPLAY_NAME – repetition {currentRepetition} of {totalRepetitions}

@DisplayName("Add operation test") @RepeatedTest(value = 5, name = RepeatedTest.LONG_DISPLAY_NAME) void addNumber(TestInfo testInfo) {	Assertions.assertEquals(2, Calculator .add(1, 1), "1 + 1 should equal 2"); }

3. RepetitionInfo interface

RepetitionInfo is used to fetch information about the current repetition of a repeated test inside the @RepeatedTest, or lifecycle methods such as @BeforeEach, and @AfterEach.

public class JUnit5AnnotationsExample {	@BeforeEach	public void initEach(RepetitionInfo info){	int currentRepetition = info.getCurrentRepetition(); int totalRepetitions = info.getTotalRepetitions(); //Use information as needed	}	@DisplayName("Add operation test")	@RepeatedTest(value = 5, name="{displayName} :: repetition {currentRepetition} of {totalRepetitions}")	void addNumber(TestInfo testInfo) {	Calculator calculator = new Calculator();	Assertions.assertEquals(2, calculator.add(1, 1), "1 + 1 should equal 2");	}	@AfterEach	public void cleanUpEach(RepetitionInfo info){	int currentRepetition = info.getCurrentRepetition(); int totalRepetitions = info.getTotalRepetitions(); //Use information as needed	} }

Happy Learning !!

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