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Developer(s)Kent Beck, Erich Gamma, David Saff, Kris Vasudevan
Stable release
5.4.2[1] / April 7, 2019 (2019-04-07)
Repository Edit this at Wikidata
Written inJava
Operating systemCross-platform
TypeUnit testing tool
LicenseEclipse Public License[2] (relicensed from CPL before)

JUnit is a unit testing framework for the Java programming language. JUnit has been important in the development of test-driven development, and is one of a family of unit testing frameworks which is collectively known as xUnit that originated with SUnit.

JUnit is linked as a JAR at compile-time; the framework resides under package junit.framework for JUnit 3.8 and earlier, and under package org.junit for JUnit 4 and later.

A research survey performed in 2013 across 10,000 Java projects hosted on GitHub found that JUnit (in a tie with slf4j-api), was the most commonly included external library; each library was used by 30.7% of projects. [3]

Example of JUnit test fixture[edit]

A JUnit test fixture is a Java object. With older versions of JUnit, fixtures had to inherit from junit.framework.TestCase, but the new tests using JUnit 4 should not do this.[4] Test methods must be annotated by the @Test annotation. If the situation requires it,[5] it is also possible to define a method to execute before (or after) each (or all) of the test methods with the @Before (or @After) and @BeforeClass (or @AfterClass) annotations.[4]

import org.junit.*;

public class FoobarTest {
    public static void setUpClass() throws Exception {
        // Code executed before the first test method

    public void setUp() throws Exception {
        // Code executed before each test
    public void testOneThing() {
        // Code that tests one thing

    public void testAnotherThing() {
        // Code that tests another thing

    public void testSomethingElse() {
        // Code that tests something else

    public void tearDown() throws Exception {
        // Code executed after each test 
    public static void tearDownClass() throws Exception {
        // Code executed after the last test method 


JUnit alternatives have been written in other languages including:

See also[edit]

  • TestNG, another test framework for Java
  • Mock object, a technique used during unit testing
  • Mockito and PowerMock, mocking extensions to JUnit
  • JUnit-Tools, a set of tools to optimize the creation and maintainability of junit-tests (www.junit-tools.org)
  • EvoSuite, a tool to automatically generate JUnit tests
  • JUnit Foundation, a set of extensions including event notifications, timeout management, automatic retry, and artifact capture.


  1. ^ JUnit Releases
  2. ^ "Relicense JUnit from CPL to EPL". Philippe Marschall. 18 May 2013. Retrieved 20 September 2013.
  3. ^ "We Analyzed 30,000 GitHub Projects – Here Are The Top 100 Libraries in Java, JS and Ruby".
  4. ^ a b Kent Beck, Erich Gamma. "JUnit Cookbook". junit.sourceforge.net. Retrieved 2011-05-21.
  5. ^ Kent Beck. "Expensive Setup Smell". C2 Wiki. Retrieved 2011-11-28.

External links[edit]