JUnit 4.x – Testing Framework : JUnit API

• JUnit Framework API
• Downloads Examples

we have to understand following in order to use JUnit for unit testing

• The class hierarchy of junit.framework Package
• What is a TestCase Class
• Working with TestCase Class
• What are assert methods
• Defining and adding necessary codes to assert methods
• The programmer has to create a JUnit Test Class (that implements the test method for testing the existing method) – This is achieved by inheriting (extends) JUnit’s TestCase class
• Define assert methods -The assert method of TestCase class is overridden by calling programmer’s Code for comparing the actual value with the expected value

What is a TestCase?

• A TestCase is a class defined in junit.framework
• Fixture are defined in TestCase to run multiple tests
• It is meant for defining test cases.

Calculator class that helps to add two number.

Calculator.java

package com.javaskool;

public class Calculator {
	
	public int add(int a,int b)
	{
		return a+b;
	}
}

CalcTest class that helps to test my Calculator class.

CalcTest.java

package com.javaskool;

import static org.junit.Assert.*;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class CalcTest {

	@Before
	public void setUp() throws Exception {
		System.out.println("Before");
	}

	@After
	public void tearDown() throws Exception {
		System.out.println("After");
	}

	@Test
	public void testAdd() {
			
		Calculator c=new Calculator();
		int x=c.add(50, 20);
		assertEquals(70, x);	//Here 70 is Expected value and x is the Actual value that would come from addition.				
		System.out.println(x);		
	}
}

Working with TestCase:

• To define a Test case class it should
• Be a subclass of TestCase
• Define instance variables
• Initialize the fixture state by overriding setUp
• Clean-up after a test
• In its own fixture so there can be no side effects among test runs.

Assert methods

• Assert methods are usually used to compare the actual value with the expected value.
• All assert methods are static methods
• Return type of all assert methods are void.
• Assert types
  • assertEquals()
  • assertTrue()
  • assertFalse(), etc…

Syntax: 
assertEquals(<datatype>,<datatype>,[<datatype>])

TestSuite

• A TestSuite is a Composite of Tests
• TestSuite runs a collection of test cases

Example:

TestSuite ts1 = new TestSuite();	
ts1.addTest(new MyTest("testAdd"));
ts1.addTest(new MyTest("testDivide"));

TestResult

• The results of executing a test case is collected by an Instance of TestResult.
• The test framework differentiates between failures and errors.
• A failure is expected and checked for with assertions.
• Errors are unexpected problems like an ArrayIndexOutOfBoundsException

TestRunner

• TestRunner is a Pre-defined class in JUnit package.
• It is meant for running either TestCase or TestSuite.
• It is a subclass of BaseTestRunner and implements TestListener interface.
• TestRunner class of junit.swingui. Package implements TestRunContext.
• Types of TestRunner are :

Click here to Download First JUnit Framework Basic Example