#junit 4

[javaknowledgecafe]

JUnit 4 - How to write a Test for an expected Exception

Not only the good weather tests should be done, also the bad weather tests. So its often the case, that you want the method you test to provoke to throw an exception. In this case of course the test was successful. So how to do this in a human readable way?

package com.tumblr.javaknowledgecafe.junit; import junit.framework.Assert; import org.junit.Test;   public class JUnitExpectedException {     // how to write     @Test(expected = Exception.class)     public void testThrowException() throws Exception { this.methodThatThrowsAnException();     }     // how you wrote it before     @Test     public void testThrowExceptionOld() { try {    this.methodThatThrowsAnException();   Assert.fail(); } catch (Exception e) {     // ignore }     }     private void methodThatThrowsAnException()  throws Exception { throw new Exception();     } }

So with the expected you get rid of FIVE lines + the code is much more readable!

Yeah you maybe say, its only four because of the //ignore-line. But I think its a bad habit to not write this line, because an other reader or maybe just you some weeks later, don't know anymore, did you forget to do something there? Much better it is with a longer statement like: //ignore, because a default value is chosen

[javaknowledgecafe]

JUnit 4 - How to make a TestSuite

With JUnit 4 - There are some really cool new features. For example you can make a TestSuite with annotations, much easier than with JUnit 3.

package com.tumblr.javaknowledgecafe.junit; import org.junit.runner.RunWith; import org.junit.runners.Suite; import com.tumblr.javaknowledgecafe.junit.TestClassOne; import com.tumblr.javaknowledgecafe.junit.TestClassTwo; @RunWith(Suite.class) @Suite.SuiteClasses({ TestClassOne.class,TestClassTwo.class }) public class AllTests { // stays empty }

Remember with JUnit 3 it was much more complicated, thats what you had to write in the constructor:

public AllTests() { TestSuite testSuite = new TestSuite(); testSuite.addTest(new TestSuite(TestClassOne.class)); testSuite.addTest(new TestSuite(TestClassTwo.class)); }