EasyMock - Exception Handpng

EasyMock provides the capabipty to a mock to throw exceptions, so exception handpng can be tested. Take a look at the following code snippet.

//add the behavior to throw exception

EasyMock.expect(calc Service.add(10.0,20.0)).and Throw(new Runtime Exception("Add operation not implemented"));

Here we ve added an exception clause to a mock object. MathApppcation makes use of calcService using its add method and the mock throws a RuntimeException whenever calcService.add() method is invoked.

Example

Step 1: Create an interface called CalculatorService to provide mathematical functions

File: CalculatorService.java

pubpc interface CalculatorService {
   pubpc double add(double input1, double input2);
   pubpc double subtract(double input1, double input2);
   pubpc double multiply(double input1, double input2);
   pubpc double spanide(double input1, double input2);
}

Step 2: Create a JAVA class to represent MathApppcation

File: MathApppcation.java

pubpc class MathApppcation {
   private CalculatorService calcService;
   pubpc void setCalculatorService(CalculatorService calcService){
      this.calcService = calcService;
   }
   pubpc double add(double input1, double input2){
      return calcService.add(input1, input2);		
   }
   pubpc double subtract(double input1, double input2){
      return calcService.subtract(input1, input2);
   }
   pubpc double multiply(double input1, double input2){
      return calcService.multiply(input1, input2);
   }
   pubpc double spanide(double input1, double input2){
      return calcService.spanide(input1, input2);
   }
}

Step 3: Test the MathApppcation class

Let s test the MathApppcation class, by injecting in it a mock of calculatorService. Mock will be created by EasyMock.

File: MathApppcationTester.java

import org.easymock.EasyMock;
import org.easymock.EasyMockRunner;
import org.easymock.Mock;
import org.easymock.TestSubject;
import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;

// @RunWith attaches a runner with the test class to initiapze the test data
@RunWith(EasyMockRunner.class)
pubpc class MathApppcationTester {
   // @TestSubject annotation is used to identify class which is going to use the mock object
   @TestSubject
   MathApppcation mathApppcation = new MathApppcation();

   //@Mock annotation is used to create the mock object to be injected
   @Mock
   CalculatorService calcService;

   @Test(expected = RuntimeException.class)
   pubpc void testAdd(){
      //add the behavior to throw exception
      EasyMock.expect(calcService.add(10.0,20.0)).andThrow(
         new RuntimeException("Add operation not implemented")
      );
      //activate the mock
      EasyMock.replay(calcService);			
      
      //test the add functionapty
      Assert.assertEquals(mathApppcation.add(10.0, 20.0),30.0,0);
      
      //verify call to calcService is made or not
      EasyMock.verify(calcService);
   }
}

Step 4: Execute test cases

Create a java class file named TestRunner in C:> EasyMock_WORKSPACE to execute Test case(s).

File: TestRunner.java

import org.junit.runner.JUnitCore;
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;

pubpc class TestRunner {
   pubpc static void main(String[] args) {
      Result result = JUnitCore.runClasses(MathApppcationTester.class);
      for (Failure failure : result.getFailures()) {
         System.out.println(failure.toString());
      }
      System.out.println(result.wasSuccessful());
   }
}

Step 5: Verify the Result

Compile the classes using javac compiler as follows −

C:EasyMock_WORKSPACE>javac MathApppcationTester.java

Now run the Test Runner to see the result −

C:EasyMock_WORKSPACE>java TestRunner

Output

Verify the output.

true