The most important package in JUnit is junit.framework, which contains all the core classes.
Some of the important classes are as follows −
Sr.No. Class Name Functionality
1 Assert A set of assert methods.
2 TestCase A test case defines the fixture to run multiple tests.
3 TestResult A TestResult collects the results of executing a test case.
4 TestSuite A TestSuite is a composite of tests.
Assert Class :-
Following is the declaration for org.junit.Assert class −
public class Assert extends java.lang.Object
This class provides a set of assertion methods useful for writing tests. Only failed assertions are recorded. Some of the important methods of Assert class are as follows −
Sr.No. Methods & Description
1 void assertEquals(boolean expected, boolean actual)
Checks that two primitives/objects are equal.
2 void assertFalse(boolean condition)
Checks that a condition is false.
3 void assertNotNull(Object object)
Checks that an object isn't null.
4 void assertNull(Object object)
Checks that an object is null.
5 void assertTrue(boolean condition)
Checks that a condition is true.
6 void fail()
Fails a test with no message.
Let's use some of the above-mentioned methods in an example. Create a java class file named TestJunit1.java in C:\>JUNIT_WORKSPACE.
import static org.junit.Assert.*;
public class TestJunit1 {
@Test
public void testAdd() {
//test data
int num = 5;
String temp = null;
String str = "Junit is working fine";
//check for equality
assertEquals("Junit is working fine", str);
//check for false condition
assertFalse(num > 6);
//check for not null value
assertNotNull(temp);
}
}
Next, create a java class file named TestRunner1.java in C:\>JUNIT_WORKSPACE to execute test case(s).
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;
public class TestRunner1 {
public static void main(String[] args) {
Result result = JUnitCore.runClasses(TestJunit1.class);
for (Failure failure : result.getFailures()) {
System.out.println(failure.toString());
}
System.out.println(result.wasSuccessful());
}
}
Compile the test case and Test Runner classes using javac.
C:\JUNIT_WORKSPACE>javac TestJunit1.java TestRunner1.java
Now run the Test Runner, which will run the test case defined in the provided Test Case class.
C:\JUNIT_WORKSPACE>java TestRunner1
Verify the output.
true
TestCase Class :-
Following is the declaration for org.junit.TestCase class −
public abstract class TestCase extends Assert implements Test
A test case defines the fixture to run multiple tests.
Some of the important methods of TestCase class are as follows −
Sr.No. Methods & Description
1 int countTestCases()
Counts the number of test cases executed by run(TestResult result).
2 TestResult createResult()
Creates a default TestResult object.
3 String getName()
Gets the name of a TestCase.
4 TestResult run()
A convenience method to run this test, collecting the results with a default TestResult object.
5 void run(TestResult result)
Runs the test case and collects the results in TestResult.
6 void setName(String name)
Sets the name of a TestCase.
7 void setUp()
Sets up the fixture, for example, open a network connection.
8 void tearDown()
Tears down the fixture, for example, close a network connection.
9 String toString()
Returns a string representation of the test case.
Let's use some of the above-mentioned methods in an example. Create a java class file named TestJunit2.java in C:\>JUNIT_WORKSPACE.
import org.junit.Before;
import org.junit.Test;
public class TestJunit2 extends TestCase {
protected double fValue1;
protected double fValue2;
@Before
public void setUp() {
fValue1 = 2.0;
fValue2 = 3.0;
}
@Test
public void testAdd() {
//count the number of test cases
System.out.println("No of Test Case = "+ this.countTestCases());
//test getName
String name = this.getName();
System.out.println("Test Case Name = "+ name);
//test setName
this.setName("testNewAdd");
String newName = this.getName();
System.out.println("Updated Test Case Name = "+ newName);
}
//tearDown used to close the connection or clean up activities
public void tearDown( ) {
}
}
Next, create a java class file named TestRunner2.java in C:\>JUNIT_WORKSPACE to execute test case(s).
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;
public class TestRunner2 {
public static void main(String[] args) {
Result result = JUnitCore.runClasses(TestJunit2.class);
for (Failure failure : result.getFailures()) {
System.out.println(failure.toString());
}
System.out.println(result.wasSuccessful());
}
}
Compile the test case and Test Runner classes using javac.
C:\JUNIT_WORKSPACE>javac TestJunit2.java TestRunner2.java
Now run the Test Runner, which will run the test case defined in the provided Test Case class.
C:\JUNIT_WORKSPACE>java TestRunner2
Verify the output.
No of Test Case = 1
Test Case Name = testAdd
Updated Test Case Name = testNewAdd
true
TestResult Class :-
Following is the declaration for org.junit.TestResult class −
public class TestResult extends Object
A TestResult collects the results of executing a test case. It is an instance of the Collecting Parameter pattern. The test framework distinguishes between failures and errors.
A failure is anticipated and checked for with assertions. Errors are unanticipated problems like an ArrayIndexOutOfBoundsException.
Some of the important methods of TestResult class are as follows −
Sr.No. Methods & Description
1 void addError(Test test, Throwable t)
Adds an error to the list of errors.
2 void addFailure(Test test, AssertionFailedError t)
Adds a failure to the list of failures.
3 void endTest(Test test)
Informs the result that a test was completed.
4 int errorCount()
Gets the number of detected errors.
5 Enumeration<TestFailure> errors()
Returns an Enumeration for the errors.
6 int failureCount()
Gets the number of detected failures.
7 void run(TestCase test)
Runs a TestCase.
8 int runCount()
Gets the number of run tests
9 void startTest(Test test)
Informs the result that a test will be started.
10 void stop()
Marks that the test run should stop.
Create a java class file named TestJunit3.java in C:\>JUNIT_WORKSPACE.
import junit.framework.AssertionFailedError;
import junit.framework.TestResult;
public class TestJunit3 extends TestResult {
// add the error
public synchronized void addError(Test test, Throwable t) {
super.addError((junit.framework.Test) test, t);
}
// add the failure
public synchronized void addFailure(Test test, AssertionFailedError t) {
super.addFailure((junit.framework.Test) test, t);
}
@Test
public void testAdd() {
// add any test
}
// Marks that the test run should stop.
public synchronized void stop() {
//stop the test here
}
}
Next, create a java class file named TestRunner3.java in C:\>JUNIT_WORKSPACE to execute test case(s).
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;
public class TestRunner3 {
public static void main(String[] args) {
Result result = JUnitCore.runClasses(TestJunit3.class);
for (Failure failure : result.getFailures()) {
System.out.println(failure.toString());
}
System.out.println(result.wasSuccessful());
}
}
Compile the test case and Test Runner classes using javac.
C:\JUNIT_WORKSPACE>javac TestJunit3.java TestRunner3.java
Now run the Test Runner, which will run the test case defined in the provided Test Case class.
C:\JUNIT_WORKSPACE>java TestRunner3
Verify the output.
true
TestSuite Class :-
Following is the declaration for org.junit.TestSuite class:
public class TestSuite extends Object implements Test
A TestSuite is a Composite of tests. It runs a collection of test cases.
Some of the important methods of TestSuite class are as follows −
Sr.No. Methods & Description
1 void addTest(Test test)
Adds a test to the suite.
2 void addTestSuite(Class<? extends TestCase> testClass)
Adds the tests from the given class to the suite.
3 int countTestCases()
Counts the number of test cases that will be run by this test.
4 String getName()
Returns the name of the suite.
5 void run(TestResult result)
Runs the tests and collects their result in a TestResult.
6 void setName(String name)
Sets the name of the suite.
7 Test testAt(int index)
Returns the test at the given index.
8 int testCount()
Returns the number of tests in this suite.
9 static Test warning(String message)
Returns a test which will fail and log a warning message.
Create a java class file named JunitTestSuite.java in C:\>JUNIT_WORKSPACE to create Test suite.
public class JunitTestSuite {
public static void main(String[] a) {
// add the test's in the suite
TestSuite suite = new TestSuite(TestJunit1.class, TestJunit2.class, TestJunit3.class );
TestResult result = new TestResult();
suite.run(result);
System.out.println("Number of test cases = " + result.runCount());
}
}
Compile the Test suite classes using javac.
C:\JUNIT_WORKSPACE>javac JunitTestSuite.java
Now run the Test Suite.
C:\JUNIT_WORKSPACE>java JunitTestSuite
Verify the output.
No of Test Case = 1
Test Case Name = testAdd
Updated Test Case Name = testNewAdd
Number of test cases = 3