junit vs TestNG – core differences

Junit and TestNG differ in the core design. Junit is a unit testing framework while TestNG addresses testing at a higher level. This article discusses the three main differences between TestNG and Junit.

1.     In Junit, one test case failure can cause a bunch of test cases to fail in the test suite. There is no option of skipping the set of dependent test cases. The dependent test cases are also reported as failures. For example, suppose there is a test case to test login and the next 10 test cases need to perform a transaction after login. If the login test case fails the other 10 test cases will also fail.

TestNG handles dependency between test cases. If one test case failure causes the failure of a group of test cases it skips that group and executes the rest of the test suite. The group that has dependency on the failed test cases is reported as skipped NOT failed.

2.     In TestNG groups can be defined. Groups are specific subsets of the test suite. We can choose to run only specific subset of the testsuite say database related test cases instead of running the entire test suite. This can be done as below:

In the test case we define two groups DBTestcase and deprecated as below:

@Test(groups = {"DBTestcase", "deprecated"})
public void testMethod2()
{
 
}

In TestNG.xml config file we write the below piece of code to include only database related test cases and exclude the deprecated ones.

<test name="Sample">
	<groups>
		<run>
			<include name="DBTestcase" />
			<exclude name="deprecated" />
		</run>
	</groups>
	<classes>
		<class name="example1.Test1" />
	</classes>
</test>

In Junit for a long time it was not possible to run a specific subset of the test cases. We can either run the entire suite or run each test case individually. Junit 4.8 introduced a new feature called “Categories” to overcome this limitation. However groups are much easier to configure in TestNG.

3.     TestNG supports parameterization for objects. For example I can execute a single test case for multiple test data sets through the parameterization of DataProvider object. This makes the implementation of data driven testing more flexible in TestNG as below:

@DataProvider(name = "DP1")
public String[][] testData() throws Exception
{
String[][] sdataArray = {{"james","moosecat$", "james@gmail.com","selenigr","selenigr1$", "selenigr@yahoo.co.uk"}};
return sdataArray;
}
 
@Test (dataProvider = "DP1")
public void evernoteSharing(String user1, String password1, String email1, String user2, String password2, String email2)
{
 
}

In junit test data is not parameterized using a DataProvider hook. Data-driven testing is implemented differently and involves more coding.

In TestNG groups can be defined. Groups are specific subsets of the test suite. We can choose to run only specific groups instead of running the entire test suite.