JUnit 4 - Basic for Java Interview

INTO to Junit
  1. @TestMark your test cases with @Test annotations. You don’t need to prefix your test cases with “test”.  In addition, your class does not need to extend from “TestCase” class.
    public void addition() {
    assertEquals(12, simpleMath.add(7, 5));
    public void subtraction() {
    assertEquals(9, simpleMath.substract(12, 3));
  2. @Before and @After
    Use @Before and @After annotations for “setup” and “tearDown” methods respectively. They run before and after every test case.
    public void runBeforeEveryTest() {
    simpleMath = new SimpleMath();
    public void runAfterEveryTest() {
    simpleMath = null;
  3. @BeforeClass and @AfterClassUse @BeforeClass and @AfterClass annotations for class wide “setup” and “tearDown” respectively. Think them as one time setup and tearDown. They run for one time before and after all test cases.
    public static void runBeforeClass() {
    // run for one time before all test cases
    public static void runAfterClass() {
    // run for one time after all test cases
  4. Exception Handling
    Use “expected” paramater with @Test annotation for test cases that expect exception. Write the class name of the exception that will be thrown.
    @Test(expected = ArithmeticException.class)
    public void divisionWithException() {
    // divide by zero
    simpleMath.divide(1, 0);
  5. @Ignore
    Put @Ignore annotation for test cases you want to ignore. You can add a string parameter that defines the reason of ignorance if you want.

    @Ignore(“Not Ready to Run”)
    public void multiplication() {
    assertEquals(15, simpleMath.multiply(3, 5));
  6. Timeout
    Define a timeout period in miliseconds with “timeout” parameter. The test fails when the timeout period exceeds.
    @Test(timeout = 1000)
    public void infinity() {
    while (true)
  7. New Assertions
    Compare arrays with new assertion methods. Two arrays are equal if they have the same length and each element is equal to the corresponding element in the other array; otherwise, they’re not.
    public static void assertEquals(Object[] expected, Object[] actual);
    public static void assertEquals(String message, Object[] expected, Object[] actual);
    public void listEquality() {
    List expected = new ArrayList();
    List actual = new ArrayList();
    assertEquals(expected, actual);
  8. JUnit4Adapter
    Run your Junit 4 tests in Junit 3 test runners with Junit4Adapter.
    public static junit.framework.Test suite() {
    return new JUnit4TestAdapter(SimpleMathTest.class);