Junit

JUnit is a unit testing framework for Java programming language. 

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

It is an open-source testing framework for java programmers. The java programmer can create test cases and test his/her own code.

It is one of the unit testing framework.

To perform unit testing, we need to create test cases. The unit test case is a code which ensures that the program logic works as expected.

The org.junit package contains many interfaces and classes for junit testing such as Assert, Test, Before, After etc.

Junit Annotations

@Test annotation specifies that method is the test method.

@Test(timeout=1000) annotation specifies that method will be failed if it takes longer than 1000 milliseconds (1 second).

@BeforeClass annotation specifies that method will be invoked only once, before starting all the tests.

@Before annotation specifies that method will be invoked before each test.

@After annotation specifies that method will be invoked after each test.

@AfterClass annotation specifies that method will be invoked only once, after finishing all the tests.

Methods of Assert class

The common methods of Assert class are as follows:

void assertEquals(boolean expected,boolean actual): checks that two primitives/objects are equal. It is overloaded.

void assertTrue(boolean condition): checks that a condition is true.

void assertFalse(boolean condition): checks that a condition is false.

void assertNull(Object obj): checks that object is null.

void assertNotNull(Object obj): checks that object is not null.