JUnit 4 has introduced a new feature called parameterized tests.
Parameterized tests allow a developer to run the same test over and
over again using different values. There are five steps that you need to
follow to create a parameterized test.
- Annotate test class with @RunWith(Parameterized.class).
- Create a public static method annotated with @Parameters that returns a Collection of Objects (as Array) as test data set.
- Create a public constructor that takes in what is equivalent to one "row" of test data.
- Create an instance variable for each "column" of test data.
- Create your test case(s) using the instance variables as the source of the test data.
Create a Class
Create a java class to be tested, say, PrimeNumberChecker.java in C:\>JUNIT_WORKSPACE.public class PrimeNumberChecker { public Boolean validate(final Integer primeNumber) { for (int i = 2; i < (primeNumber / 2); i++) { if (primeNumber % i == 0) { return false; } } return true; } }
Create Parameterized Test Case Class
Create a java test class, say, PrimeNumberCheckerTest.java. Create a java class file named PrimeNumberCheckerTest.java in C:\>JUNIT_WORKSPACE.import java.util.Arrays; import java.util.Collection; import org.junit.Test; import org.junit.Before; import org.junit.runners.Parameterized; import org.junit.runners.Parameterized.Parameters; import org.junit.runner.RunWith; import static org.junit.Assert.assertEquals; @RunWith(Parameterized.class) public class PrimeNumberCheckerTest { private Integer inputNumber; private Boolean expectedResult; private PrimeNumberChecker primeNumberChecker; @Before public void initialize() { primeNumberChecker = new PrimeNumberChecker(); } // Each parameter should be placed as an argument here // Every time runner triggers, it will pass the arguments // from parameters we defined in primeNumbers() method public PrimeNumberCheckerTest(Integer inputNumber, Boolean expectedResult) { this.inputNumber = inputNumber; this.expectedResult = expectedResult; } @Parameterized.Parameters public static Collection primeNumbers() { return Arrays.asList(new Object[][] { { 2, true }, { 6, false }, { 19, true }, { 22, false }, { 23, true } }); } // This test will run 4 times since we have 5 parameters defined @Test public void testPrimeNumberChecker() { System.out.println("Parameterized Number is : " + inputNumber); assertEquals(expectedResult, primeNumberChecker.validate(inputNumber)); } }
Create Test Runner Class
Create a java class file named TestRunner.java in C:\>JUNIT_WORKSPACE to execute test case(s).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(PrimeNumberCheckerTest.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }Compile the PrimeNumberChecker, PrimeNumberCheckerTest and Test Runner classes using javac.
C:\JUNIT_WORKSPACE>javac PrimeNumberChecker.java PrimeNumberCheckerTest.java TestRunner.javaNow run the Test Runner, which will run the test cases defined in the provided Test Case class.
C:\JUNIT_WORKSPACE>java TestRunnerVerify the output.
Parameterized Number is : 2 Parameterized Number is : 6 Parameterized Number is : 19 Parameterized Number is : 22 Parameterized Number is : 23 true
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