JUnit is a framework for writing tests in Java. We currently use JUnit 4.7 for our tests, which still supports the older JUnit 3.8 syntax.

A simple example of a testcase:

 import org.junit.Assert;
 import org.junit.Test;

 public class MyTests {
     @Test
     public final void testOne() {
         // your code here...
         Assert.assertEquals(expectedValue, actualValue);
     }
     @Test
     public final void testTwo() {
         // your code here...
         Assert.assertNotNull(someObject);
     }
     @Test @Ignore("not yet fully implemented")
     public final void testThree() {
         // your code here...
         // TODO complete test
     }
 }

This code defines three tests (testOne, testTwo, testThree). JUnit offers many different assert-statements which should be used to verify the results of your tests. Do not use the standard assert() offered by Java, as this must especially be enabled to be evaluated! If a test is not yet fully implemented but you still want to commit the code, add the annotation @Ignore to the test. In that case, the test will not be executed. Note that your code must still compile when committing ignored tests.

If you need to read in or write out files to disk, use MatsimTestUtils as a rule:

 import org.junit.Assert;
 import org.junit.Rule;
 import org.junit.Test;

 public class MyTests {
     @Rule public MatsimTestUtils utils = new MatsimTestUtils();
     @Test
     public final void testOne() {
         String inputFile = utils.getInputDirectory() + "myFile.txt";
         // your code here...
         String outputFile = utils.getOutputDirectory() + "myFile.txt";
         Assert.assertEquals(expectedValue, actualValue);
     }
 }

Please note that many methods of MatsimTestUtils can only be used in the actual test (marked with @Test), but not in a constructor or other initialization methods (e.g. in @Before).