JUnit is used for unit testing of Java applications. JUnit and TestNG are two popular unit testing frameworks. In this tutorial I will explore JUnit only.

There are two popular version of JUnit – JUnit 3 and JUnit 4. Below table shows few important differences in these versions . Apart from this there is one more important difference that from JUnit 4.7 parallel execution of JUnit test cases is supported.

JUnit 3.x Sample

import junit.framework.*;
public class MoneyTest extends TestCase {
	private Money f12CHF;			// fixtures
	private Money f14CHF;

	protected void setUp() {		// create the test data
		f12CHF = new Money(12, "CHF");
		f14CHF = new Money(14, "CHF");
	}
   void testAdd() {				// create the test data
		Money expected = new Money(26, “CHF”);
		assertEquals(“amount not equal”,
                     expected,f12CHF.add(f14CHF);
	}
	...
}

JUnit 4.x Sample

import junit.framework.*;
import org.junit.*;
import static org.junit.Assert.*;
public class MoneyTest <del>extends TestCase</del> {
	private Money f12CHF;
	private Money f14CHF;

	@Before
        public void setUp() // setup, teardown function names are not mandatory now as we have annotations now
        {
		f12CHF = new Money(12, "CHF");    // - the fixture
		f14CHF = new Money(14, "CHF");
	}
	@Test
        public void testAdd() // create the test data
        {
		Money expected = new Money(26, “CHF”);
		assertEquals(“amount not equal”,
                     expected,f12CHF.add(f14CHF));
	}
	...
}

Following changes were happened in JUnit 4.x

1. No need to start test method name with prefix “test”.
2. @BeforeClass and @AfterClass were introduced
   1. @BeforeClass method – executes only once; before the first test method
   2. @AfterClass method – executes only once; after the last test method
3. Instead of setup and tearDown now JUnit 4 has @Before and @After annotations.
   1. @Before method – executes every time; before the test method.
   2. @After method – executes every time; after the test method.
4. @Ignore was introduced to skip a test case while running.
5. “expected” was introduced to tell JUnitRunner that what exception we are expecting. Example : @Test(expected=ArithmeticException.class)
6. “timeout” was introduced to put a time limit on a testcase. If test does not complete in that time limit, an exception will raise with message “test timed out after xxx milliseconds”

Next posts will show the working examples with these annotations.