How to Set Custom Names for Parameterized Tests in JUnit 4

How can I customize test case names in JUnit 4 parameterized tests?

@RunWith(Parameterized.class)
public class MyTests {

    @Parameterized.Parameters
    public static Collection<Object[]> data() {
        return Arrays.asList(new Object[][] {
            { "test1", 1 },
            { "test2", 2 }
        });
    }

    private String name;
    private int value;

    public MyTests(String name, int value) {
        this.name = name;
        this.value = value;
    }

    @Test
    public void testMethod() {
        System.out.println(name + " is testing with value " + value);
        // Implement actual test logic
    }
}

JUnit 4 provides a framework for creating parameterized tests, allowing you to run the same test with different inputs. However, by default, the test case names are generated in a generic format like [Test class].runTest[n]. To enhance clarity and maintainability, customizing these names can be essential.

@RunWith(Parameterized.class)
public class MyTests {

    @Parameterized.Parameters(name="{0}")
    public static Collection<Object[]> data() {
        return Arrays.asList(new Object[][] {
            { "test name 1", 1 },
            { "test name 2", 2 }
        });
    }

    private String name;
    private int value;

    public MyTests(String name, int value) {
        this.name = name;
        this.value = value;
    }

    @Test
    public void testMethod() {
        // Your test logic here
    }
}

Causes

• Default naming conventions in JUnit 4 do not reflect the test scenarios effectively.
• Parameterization can lead to ambiguous output if not named properly.

Solutions

• Implement the constructor of your test class to take a specific name as a parameter.
• Override the toString() method of the test case to return the custom name.

Mistake: Not providing a proper custom name in the parameters collection.

Solution: Ensure that the name is the first element of the parameters array passed to the data() method.

Mistake: Failing to customize test method behavior based on parameters.

Solution: Ensure the test logic uses the parameterized inputs correctly to validate the expected outcomes.