What is Junit Test Framework?

JUnit is a Regression Testing Framework used by developers to implement unit testing in Java and accelerate programming speed and increase the quality of code. JUnit Framework can be easily integrated with either of the followings:

1.Eclipse
2.Ant
3.Maven

Features:JUnit test framework provides following important features

1. Fixtures
2. Test suites
3. Test runners
4. JUnit classes
5. Fixtures

Fixtures is a fixed state of a set of objects used as a baseline for running tests. The purpose of a test fixture is to ensure that there is a well known and fixed environment in which tests are run so that results are repeatable. It includes

setUp() method which runs before every test invocation.

tearDown() method which runs after every test method.

Let's check one example:import junit.framework.*; public class JavaTest extends TestCase { protected int value1, value2; // assigning the values protected void setUp(){ value1=3; value2=3; } // test method to add two values public void testAdd(){ double result= value1 + value2; assertTrue(result == 6); } }

Test suite:

Test suite means bundle a few unit test cases and run it together. In JUnit, both @RunWith and @Suite annotation are used to run the suite test. Here is an example which uses TestJunit1 & TestJunit2 test classes.import org.junit.runner.RunWith; import org.junit.runners.Suite; //JUnit Suite Test @RunWith(Suite.class) @Suite.SuiteClasses({ TestJunit1.class ,TestJunit2.class }) public class JunitTestSuite { }
import org.junit.Test; import org.junit.Ignore; import static org.junit.Assert.assertEquals; public class TestJunit1 { String message = "Robert"; MessageUtil messageUtil = new MessageUtil(message); @Test public void testPrintMessage() { System.out.println("Inside testPrintMessage()"); assertEquals(message, messageUtil.printMessage()); } }
import org.junit.Test; import org.junit.Ignore; import static org.junit.Assert.assertEquals; public class TestJunit2 { String message = "Robert"; MessageUtil messageUtil = new MessageUtil(message); @Test public void testSalutationMessage() { System.out.println("Inside testSalutationMessage()"); message = "Hi!" + "Robert"; assertEquals(message,messageUtil.salutationMessage()); } }

Test runner:

Test runner is used for executing the test cases. Here is an example which assumes TestJunit test class already exists.import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(TestJunit.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }

JUnit classes:

JUnit classes are important classes which is used in writing and testing JUnits. Some of the important classes are

Assert which contain a set of assert methods.

TestCase which contain a test case defines the fixture to run multiple tests.

TestResult which contain methods to collect the results of executing a test case