1. JUnit
SWE 619
Spring 2008

2. SWE 619 (c) Aynur Abdurazik
What is JUnit?
Open source Java testing framework used to write and run repeatable automated tests
JUnit features include:
Assertions for testing expected results
Test fixtures for sharing common test data
Test suites for easily organizing and running tests
Graphical and textual test runners
July 18, 2007
SWE 619 (c) Aynur Abdurazik

3. Test Scenarios with JUnit
Used to test
A whole object
Part of an object - a method or some interacting methods
Interaction between several objects
A test case represents one scenario
A tester class contains more than one scenario
Each senario is written into one test method
July 18, 2007
SWE 619 (c) Aynur Abdurazik

4. Writing Tests for JUnit
Need to use the methods of the junit.framework.assert class
javadoc gives a complete description of its capabilities
Each of these methods checks some condition and reports back to the test runner whether the test failed or succeeded.
The test runner uses the result to update the display. All of the methods return void (i.e. they are procedures)
July 18, 2007
SWE 619 (c) Aynur Abdurazik

5. Writing Tests for JUnit – (cont’d)
A few representative methods of junit.framework.assert
assertTrue(boolean)
assertTrue(String, boolean)
assertEquals(Object, Object)
assertNull(Object)
fail(String)
assertTrue(boolean)
You can supply any boolean expression to this method, and as long as the boolean expression evaluates to true, the method reports success. If the condition you want to check should be false, simply prepend the "!" negation operator to your parenthesized expression.
assertTrue(String, boolean)
Same as the first form of assertTrue, except that the supplied String is printed if the assertion fails. Most methods have a version of this form with a message string.
assertEquals(Object, Object)
Compares the two objects you pass in using the equals( ) method.
assertNull(Object)
Succeeds if the Object reference passed in is null. There is also an assertNotNull method.
fail(String)
Causes the test to fail, printing out the supplied String.
July 18, 2007
SWE 619 (c) Aynur Abdurazik

6. Sample Assertions (cont’d)
static void assertEquals(boolean expected, boolean actual)           Asserts that two booleans are equal.
static void assertEquals(byte expected, byte actual)           Asserts that two bytes are equal.
static void assertEquals(char expected, char actual)           Asserts that two chars are equal.
static void assertEquals(double expected, double actual, double delta)           Asserts that two doubles are equal concerning a delta.
static void assertEquals(float expected, float actual, float delta)           Asserts that two floats are equal concerning a delta.
static void assertEquals(int expected, int actual)           Asserts that two ints are equal.
For a complete list, see
July 18, 2007
SWE 619 (c) Aynur Abdurazik

7. SWE 619 (c) Aynur Abdurazik
How to write test case
Two different ways for junit versions 3.X and 4.x.
In Junit 3.X
1) import junit.framework.* 2) extend TestCase.
3) name the test methods with a prefix of ‘test’
4) validate conditions using one of the several assert methods
July 18, 2007
SWE 619 (c) Aynur Abdurazik

8. How to write test case (cont’d)
In Junit 4.0 and later:
Do not extend from Junit.framework.TestCase
Do not prefix the test method wit ‘test’
Use one of the assert methods
Run the test using JUnit4TestAdapter
July 18, 2007
SWE 619 (c) Aynur Abdurazik

9. SWE 619 (c) Aynur Abdurazik
Simple Example
public class Math {         static public int add(int a, int b) {                   return a + b;         } }
July 18, 2007
SWE 619 (c) Aynur Abdurazik

10. Example JUnit test case
import junit.framework.*;
public class TestMath extends TestCase {
  public void testAdd() {         int num1 = 3;         int num2 = 2;         int total = 5;         int sum = 0;         sum = Math.add(num1, num2);         assertEquals(sum, total);   } } 
July 18, 2007
SWE 619 (c) Aynur Abdurazik

11. Testing the Stack class
public class Stack{
public String toString() {
// EFFECTS: Returns the String representation of this Stack from the
// top to the bottom.
StringBuffer buf = new StringBuffer("{");
for (int i = size-1; i >= 0; i--) {
if (i < (size-1)) {
buf.append(", "); }
buf.append(elements[i].toString());
buf.append("}");
return buf.toString();
public boolean repOk() {
if (elements == null) return false;
if (size != elements.length) return false;
for (int i = 0; i < size; i++) {
if (elements[i] == null) return false;
return true;
July 18, 2007
SWE 619 (c) Aynur Abdurazik

12. TestCases with JUnit 4.X for Stack
Necessary classes to be imported:
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import static org.junit.Assert.assertEquals;
import junit.framework.JUnit4TestAdapter;
July 18, 2007
SWE 619 (c) Aynur Abdurazik

13. SWE 619 (c) Aynur Abdurazik
TestCases with JUnit (Cont’d)
public class StackTest {
private Stack stack;
/**
* setUp method annotation.
* Method can be named anything. */
@Before public void runBeforeEachTest(){
stack = new Stack(); }
July 18, 2007
SWE 619 (c) Aynur Abdurazik

14. Test case with JUnit (cont’d)
@Test public void testRepOk(){
boolean result = stack.repOk();
assertEquals(true, result);
stack = stack.push(new Integer(1));
result = stack.repOk();
stack = stack.pop();
stack.top(); }
July 18, 2007
SWE 619 (c) Aynur Abdurazik

15. Test case with JUnit (cont’d)
@Test public void testToString(){
stack = stack.push(new Integer(1));
stack = stack.push(new Integer(2));
assertEquals("{2, 1}", stack.toString()); }
@After public void runAfterEachTest(){
stack = null;
public static junit.framework.Test suite(){
return new JUnit4TestAdapter(StackTest.class);
July 18, 2007
SWE 619 (c) Aynur Abdurazik

16. SWE 619 (c) Aynur Abdurazik
How to Run Tests
JUnit provides test drivers
Character-based test driver runs from the command line
GUI-based test driver-junit.swingui.TestRunner
allows to specify the test class to run,
"Run" button
examines the chosen class and finds all methods whose names begin with "test."
If a test fails, Junit gives the location of the failure and any exceptions that were thrown
July 18, 2007
SWE 619 (c) Aynur Abdurazik

17. JUnit Installation in Eclipse
In Eclipse, select Help->Software Updates->Find and Install
Choose 'Search For New Features to Install' and select 'Next'
Select 'New Remote Site'
Enter a name for this server: JUnit Factory
Enter (or copy/paste) this url:
Install all plug-ins in the 'JUnit Factory' category and restart Eclipse
assertTrue(boolean)
You can supply any boolean expression to this method, and as long as the boolean expression evaluates to true, the method reports success. If the condition you want to check should be false, simply prepend the "!" negation operator to your parenthesized expression.
assertTrue(String, boolean)
Same as the first form of assertTrue, except that the supplied String is printed if the assertion fails. Most methods have a version of this form with a message string.
assertEquals(Object, Object)
Compares the two objects you pass in using the equals( ) method.
assertNull(Object)
Succeeds if the Object reference passed in is null. There is also an assertNotNull method.
fail(String)
Causes the test to fail, printing out the supplied String.
July 18, 2007
SWE 619 (c) Aynur Abdurazik

18. Generating Tests in Eclipse
Select a Java class in Eclipse and click the Generate Tests ( )button
When the JUnit Factory view says your test is done, click the link in the Result column to open it
Select the test and choose Run->Run As->Agitar JUnit Test from the main menu
July 18, 2007
SWE 619 (c) Aynur Abdurazik

19. SWE 619 (c) Aynur Abdurazik
Eclipse JUnit Plugin
See tutorial
July 18, 2007
SWE 619 (c) Aynur Abdurazik