JUnit - Test Suites

JUnit – Test Suites

In this tutorial, you will learn about JUnit test suites. These Test Suites allows you to group multiple test classes and run them together as a single unit.

JUnit test suites are defined using the @Suite annotation, which groups a collection of test classes.

What Are Test Suites?

A test suite in JUnit is a way to bundle multiple test classes so that they can be run together as a group.

A Test Suite is useful for:

Testing specific features or modules by including only related test classes.
Running regression tests or a subset of critical tests.
Organizing and managing tests for better scalability in large projects.

JUnit 5 supports test suites through the @Suite annotation provided by the org.junit.platform.suite.api package.

How to Create a Test Suite

To create a test suite in JUnit 5, follow these steps:

1 Add Required Dependencies

Ensure that your project includes the JUnit 5 dependency. If you’re using Maven, add the following to your pom.xml:

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<dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter</artifactId>
    <version>5.x.x</version>
    <scope>test</scope>
</dependency>

2 Create Test Classes

Create individual test classes for the features you want to test. For example:

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import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;

class MathTest {

    @Test
    void testAddition() {
        assertEquals(5, 2 + 3, "2 + 3 should equal 5");
    }
}

class StringTest {

    @Test
    void testConcatenation() {
        assertEquals("Hello World", "Hello " + "World", "Strings should concatenate correctly");
    }
}

3 Define the Test Suite

Create a suite class that groups the test classes using the @Suite annotation:

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import org.junit.platform.suite.api.SelectClasses;
import org.junit.platform.suite.api.Suite;

@Suite
@SelectClasses({ MathTest.class, StringTest.class })
class MyTestSuite {
    // This class remains empty. It is used only as a holder for the annotations.
}

Explanation:

@Suite: Indicates that the class is a test suite.
@SelectClasses: Specifies the test classes to include in the suite.

4 Run the Test Suite

Run the test suite like any other test class using your IDE or build tool (e.g., Maven or Gradle). JUnit will execute all the included test classes.

Advanced Suite Configuration

JUnit 5 provides additional annotations for more advanced test suite configurations. Let’s explore them:

1 Include Tests by Package

Use the @SelectPackages annotation to include all test classes from specific packages:

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import org.junit.platform.suite.api.SelectPackages;
import org.junit.platform.suite.api.Suite;

@Suite
@SelectPackages("com.example.tests")
class PackageTestSuite {
    // This suite will include all tests in the specified package.
}

2 Filtering Tests with Tags

You can use the @IncludeTags and @ExcludeTags annotations to filter tests based on tags:

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import org.junit.platform.suite.api.IncludeTags;
import org.junit.platform.suite.api.Suite;

@Suite
@IncludeTags("regression")
class TaggedTestSuite {
    // Only tests tagged with "regression" will be included in this suite.
}

3 Combine Annotations

You can combine annotations like @SelectClasses, @SelectPackages, and @IncludeTags to create highly customized test suites.

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import org.junit.platform.suite.api.*;

@Suite
@SelectPackages("com.example.tests")
@IncludeTags("critical")
class CombinedTestSuite {
    // Includes only tests in the specified package and tagged as "critical."
}

Best Practices for Test Suites

Group Logically: Organize tests into suites based on features, modules, or categories like regression, integration, and unit tests.
Keep Suites Lightweight: Avoid adding too many classes or tests to a single suite to maintain fast execution times.
Use Tags Strategically: Leverage tags to include or exclude tests dynamically based on the testing context.
Maintain Modular Tests: Ensure that tests are independent so that suites can be executed without interference between test cases.

Conclusion

JUnit test suites provide a powerful way to organize and execute groups of tests. Whether you’re managing tests by feature, package, or tags, test suites enable efficient execution and better scalability for large projects. By following the examples and best practices outlined in this guide, you can build well-organized and maintainable test suites that streamline your testing process and improve overall project quality.

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JUnit – Test Suites