Enterprise Java

Parameterized JUnit tests

Sometimes you encounter a problem that just screams for using “parameterized” tests rather than copy/pasting the same method many times.   The test method is basically the same and the only thing that changes is the data passed in.  In this case, consider creating a test case that utilitizes the ” Parameterized” class from JUnit.

I recently ran into a problem where our validation of an email address did not allow unicode characters.  The fix was fairly straight-forward, change the regular expression to allow those characters.  Next, it was time to test the change.  Rather than copy/paste separate methods for each set of data, I decided to learn about the Parameterized method.   Below is the result.  The data includes the expected result and the email address to be validated.

JUnit test class

package com.mycompany.client;
import static org.junit.Assert.*;
import java.util.Arrays;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;
import com.mycompany.test.TestServiceUtil;
 * Parameterized test case for validating email addresses against a regular expression.
 * We need to allow unicode characters in the userid portion of the email address, so 
 * these test cases where created to help validate the validateEmailAddress method
 * in the FieldValidationController class.
 * @author mmiller
public class TestFieldValiationController {
    @Parameters(name = "{index}: {1} is valid email address = {0}")
    public static Iterable<Object> data() {
        return Arrays.asList(new Object[][] { 
         { true, "john@mycomp.com" },           { true,  "john123@mycomp.com" },
         { true, "j+._%20_-brown@mycomp.com" }, { true,  "123@mycomp.com" },
         { false, "john brown@mycomp.com" },    { false, "123@mycomp" },
         { false, "john^brown@mycomp.com" },    { true , "1john@mycomp.com" },
         { false, "john#brown@mycomp.com" },    { false, "john!brown@mycomp.com" },
         { false, "john()brown@mycomp.com" },   { false, "john=brown@mycomp.com" },
         { true,  "johñ.brown@mycomp.com" },    { false, "john.brown@mycomp.coñ" },
         { true,  "johú@mycomp.com" },          { true,  "johíáó@mycomp.com" }
    private boolean expected;
    private String emailAddress;
    public TestFieldValiationController(boolean expected, String emailAddress) {
        this.expected = expected;
        this.emailAddress = emailAddress;
    public void validateEmail() {
        assertEquals(expected, FieldValidationController.getInstance().validateEmailAddress(emailAddress));

Hope this helps!

Reference: Parameterized JUnit tests from our JCG partner Mike Miller at the Scratching my programming itch blog.

Mike Miller

Mike is a software developer who loves to learn how things work. A Java programmer who caught the Groovy & Grails itch and is always looking for opportunities to include them as part of the solution.
Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Newest Most Voted
Inline Feedbacks
View all comments
10 years ago

I assume the line 46 is redundant?

10 years ago

Parametrization of tests is easier with TestNG.

Artur Szeja
Artur Szeja
10 years ago

You didn’t mention that the functionality of customized test names is available since JUnit 4.11

Back to top button