Junit: @Test: Test the exception

@Test annotation provides an optional argument 'expected', by using this, you can test the exception thrown by a method.

Example

         @Test(expected=IllegalArgumentException.class)

         public void divide_10By0_IllegalArgumentException() {

                 

                  Arithmetic obj1 = new Arithmetic();

                  obj1.divide(10, 0);

                 

         }

Find the below working application.

Arithmetic.java

package com.sample.arithmetic;

public class Arithmetic {

 public int divide(int a, int b) {
  if (b == 0) {
   throw new IllegalArgumentException("Division by zero is not supported");
  }

  return a / b;
 }
}

ArithmeticTest.java

package com.sample.arithmetic;

import org.junit.Test;

/**
 * Test cases follow below naming convention. 
 *  methodName_input_output format.
 * 
 * @author krishna
 *
 */
public class ArithmeticTest {

 @Test(expected=IllegalArgumentException.class)
 public void divide_10By0_IllegalArgumentException() {
  
  Arithmetic obj1 = new Arithmetic();
  obj1.divide(10, 0);
  
 }
}

Above approach is good in testing the exceptions thrown by a method. Sometimes you may want to test the exception message also. In my next post, I will explain about this.

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