Java Tutorial/JUnit/TestCase

extends TestCase

   <source lang="java">

import junit.framework.*; public class TestSimple extends TestCase {

 public TestSimple(String name) {
   super(name);
 }
 public void testAdd() {
   assertEquals(2, 1+1);
 }

}</source>

Init class being tested in test case method

   <source lang="java">

import junit.framework.Test; import junit.framework.TestCase; import junit.framework.TestSuite; public class TestClassTwo extends TestCase {

 public TestClassTwo(String method) {
   super(method);
 }
 public void testLongRunner() {
   TSP tsp = new TSP();
   assertEquals(2300, tsp.shortestPath(50));
 }
 public void testShortTest() {
   TSP tsp = new TSP();
   assertEquals(140, tsp.shortestPath(5));
 }
 public void testAnotherShortTest() {
   TSP tsp = new TSP();
   assertEquals(586, tsp.shortestPath(10));
 }
 public static Test suite() {
   TestSuite suite = new TestSuite();
   // Only include short tests
   suite.addTest(new TestClassTwo("testShortTest"));
   suite.addTest(new TestClassTwo("testAnotherShortTest"));
   return suite;
 }

} class TSP {

 public int shortestPath(int numCities) {
   switch (numCities) {
   case 50:
     return 2300;
   case 5:
     return 140;
   case 10:
     return 586;
   }
   return 0;
 }

}</source>

JUnit Test Composition

   <source lang="java">

import junit.framework.*; public class TestClassOne extends TestCase {

 public TestClassOne(String method) {
   super(method);
 }
 public void testAddition() {
   assertEquals(4, 2+2);
 }
 public void testSubtraction() {
   assertEquals(0, 2-2);
 }

}</source>

Per-Test Setup and Tear-Down

   <source lang="java">

import java.sql.Connection; import junit.framework.TestCase; public class TestDB extends TestCase {

 private Connection dbConn;
 protected void setUp() {
   // connect to database
 }
 protected void tearDown() {
   // disconnect from database
 }
 public void testAccountAccess() {
 }
 public void testEmployeeAccess() {
 }

}</source>

Test algorithm

   <source lang="java">

import junit.framework.TestCase; public class TestLargest extends TestCase {

 public TestLargest(String name) {
   super(name);
 }
 public void testOrder() {
   assertEquals(9, Largest.largest(new int[] { 9, 8, 7 }));
   assertEquals(9, Largest.largest(new int[] { 8, 9, 7 }));
   assertEquals(9, Largest.largest(new int[] { 7, 8, 9 }));
 }
 public void testEmpty() {
   try {
     Largest.largest(new int[] {});
     fail("Should have thrown an exception");
   } catch (RuntimeException e) {
     assertTrue(true);
   }
 }
 public void testOrder2() {
   int[] arr = new int[3];
   arr[0] = 8;
   arr[1] = 9;
   arr[2] = 7;
   assertEquals(9, Largest.largest(arr));
 }

} class Largest {

 public static int largest(int[] list) {
   int index, max = Integer.MAX_VALUE;
   if (list.length == 0) {
     throw new RuntimeException("Empty list");
   }
   for (index = 0; index < list.length - 1; index++) {
     if (list[index] > max) {
       max = list[index];
     }
   }
   return max;
 }

}</source>

Test Skeleton

   <source lang="java">

import junit.framework.Test; import junit.framework.TestCase; import junit.framework.TestSuite; public class TestSkeleton extends TestCase {

 /**
  * Per-method test set up
  */
 public void setUp() {
 }
 /**
  * Per-method test tear down
  */
 public void tearDown() {
 }
 /**
  * Add tests here: public void testName() ...
  */
 public TestSkeleton(String name) {
   super(name);
 }
 /**
  * Default suite method
  */
 public static Test suite() {
   return new TestSuite(TestSkeleton.class);
 }
 /**
  * Note -- "main" will only be run when invoked individually from the command
  * line (not via Ant"s JUnit Task, etc.)
  */
 public static void main(String[] args) {
   TestSuite suite = new TestSuite();
   if (args.length != 0) {
     // Run specific tests as indicated from the
     // command line
     for (int i = 0; i < args.length; i++) {
       suite.addTest(new TestSkeleton(args[i]));
     }
   } else {
     // Dynamically discover all of them, or use
     // user-defined suite
     suite.addTest(TestSkeleton.suite());
   }
   junit.textui.TestRunner.run(suite);
 }

}</source>

Test your stack structure

   <source lang="java">

import junit.framework.TestCase; public class TestMyStack extends TestCase {

 public void testEmpty() throws Exception {
   MyStack stack = new MyStack();
   stack.checkInvariant();
   stack.push("sample");
   stack.checkInvariant();
   assertEquals("sample", stack.pop());
   stack.checkInvariant();
   stack.delete(1);
   stack.checkInvariant();
 }

} class MyStack {

 public MyStack() {
   stack = new String[100];
   next_index = 0;
 }
 public String pop() {
   return stack[--next_index];
 }
 public void delete(int n) {
   next_index -= n;
 }
 public void push(String aString) {
   stack[next_index++] = aString;
 }
 public String top() {
   return stack[next_index - 1];
 }
 public void checkInvariant() throws Exception {
   if (!(next_index >= 0 && next_index < stack.length)) {
     throw new Exception("next_index out of range: " + next_index + " for stack length "
         + stack.length);
   }
 }
 private int next_index;
 private String[] stack;

}</source>

Use assertEquals in a test method

   <source lang="java">

import junit.framework.TestCase; public class TestLargest extends TestCase {

 public TestLargest(String name) {
   super(name);
 }
 public void testAdds() {
   assertEquals(2, 1 + 1);
   assertEquals(4, 2 + 2);
   assertEquals(-8, -12 + 4);
 }

}</source>