JUnit 4 and TestNG are both very popular unit test framework in Java. Both frameworks look very similar in functionality. Which one is better? Which unit test framework should I use in Java project?
Here I did a feature comparison between JUnit 4 and TestNG.
junit-vs-testngjpg

1. Annotation Support

The annotation supports are implemented in both JUnit 4 and TestNG look similar.
FeatureJUnit 4TestNG
test annotation@Test@Test
run before all tests in this suite have run–@BeforeSuite
run after all tests in this suite have run–@AfterSuite
run before the test–@BeforeTest
run after the test–@AfterTest
run before the first test method that belongs to any of these groups is invoked–@BeforeGroups
run after the last test method that belongs to any of these groups is invoked–@AfterGroups
run before the first test method in the current class is invoked@BeforeClass@BeforeClass
run after all the test methods in the current class have been run@AfterClass@AfterClass
run before each test method@Before@BeforeMethod
run after each test method@After@AfterMethod
ignore test@ignore@Test(enbale=false)
expected exception@Test(expected = ArithmeticException.class)@Test(expectedExceptions = ArithmeticException.class)
timeout@Test(timeout = 1000)@Test(timeout = 1000)
The main annotation differences between JUnit4 and TestNG are
1. In JUnit 4, we have to declare “@BeforeClass” and “@AfterClass” method as static method. TestNG is more flexible in method declaration, it does not have this constraints.
2. 3 additional setUp/tearDown level: suite and group (@Before/AfterSuite, @Before/AfterTest, @Before/AfterGroup). See more detail here.
JUnit 4
    @BeforeClass
    public static void oneTimeSetUp() {
        // one-time initialization code   
    	System.out.println("@BeforeClass - oneTimeSetUp");
    }
TestNG
    @BeforeClass
    public void oneTimeSetUp() {
        // one-time initialization code   
    	System.out.println("@BeforeClass - oneTimeSetUp");
}
In JUnit 4, the annotation naming convention is a bit confusing, e.g “Before”, “After” and “Expected”, we do not really understand what is “Before” and “After” do, and what we “Expected” from test method? TestiNG is easier to understand, it uses “BeforeMethod”, “AfterMethod” and “ExpectedException” instead.

2. Exception Test

The “exception testing” means what exception throws from the unit test, this feature is implemented in both JUnit 4 and TestNG.
JUnit 4
      @Test(expected = ArithmeticException.class)  
	public void divisionWithException() {  
	  int i = 1/0;
	}
TestNG
      @Test(expectedExceptions = ArithmeticException.class)  
	public void divisionWithException() {  
	  int i = 1/0;
	}

3. Ignore Test

The “Ignored” means whether it should ignore the unit test, this feature is implemented in both JUnit 4 and TestNG .
JUnit 4
        @Ignore("Not Ready to Run")  
	@Test
	public void divisionWithException() {  
	  System.out.println("Method is not ready yet");
	}
TestNG
	@Test(enabled=false)
	public void divisionWithException() {  
	  System.out.println("Method is not ready yet");
	}

4. Time Test

The “Time Test” means if an unit test takes longer than the specified number of milliseconds to run, the test will terminated and mark as fails, this feature is implemented in both JUnit 4 and TestNG .
JUnit 4
        @Test(timeout = 1000)  
	public void infinity() {  
		while (true);  
	}
TestNG
	@Test(timeOut = 1000)  
	public void infinity() {  
		while (true);  
	}

5. Suite Test

The “Suite Test” means bundle a few unit test and run it together. This feature is implemented in both JUnit 4 and TestNG. However both are using very different method to implement it.
JUnit 4
The “@RunWith” and “@Suite” are use to run the suite test. The below class means both unit test “JunitTest1” and “JunitTest2” run together after JunitTest5 executed. All the declaration is define inside the class.
@RunWith(Suite.class)
@Suite.SuiteClasses({
        JunitTest1.class,
        JunitTest2.class
})
public class JunitTest5 {
}
TestNG
XML file is use to run the suite test. The below XML file means both unit test “TestNGTest1” and “TestNGTest2” will run it together.

 name="My test suite">
   name="testing">
    
        name="com.fsecure.demo.testng.TestNGTest1" />
        name="com.fsecure.demo.testng.TestNGTest2" />