Setting up JUnit with IntelliJ IDEA [duplicate]

  1. Create and setup a "tests" folder
    • In the Project sidebar on the left, right-click your project and do New > Directory. Name it "test" or whatever you like.
    • Right-click the folder and choose "Mark Directory As > Test Source Root".
  2. Adding JUnit library
    • Right-click your project and choose "Open Module Settings" or hit F4. (Alternatively, File > Project Structure, Ctrl-Alt-Shift-S is probably the "right" way to do this)
    • Go to the "Libraries" group, click the little green plus (look up), and choose "From Maven...".
    • Search for "junit" -- you're looking for something like "junit:junit:4.11".
    • Check whichever boxes you want (Sources, JavaDocs) then hit OK.
    • Keep hitting OK until you're back to the code.
  3. Write your first unit test

    • Right-click on your test folder, "New > Java Class", call it whatever, e.g. MyFirstTest.
    • Write a JUnit test -- here's mine:

      import org.junit.Assert;
      import org.junit.Test;
      
      public class MyFirstTest {
          @Test
          public void firstTest() {
              Assert.assertTrue(true);
          }
      }
      
  4. Run your tests
    • Right-click on your test folder and choose "Run 'All Tests'". Presto, testo.
    • To run again, you can either hit the green "Play"-style button that appeared in the new section that popped on the bottom of your window, or you can hit the green "Play"-style button in the top bar.

Basically, you only need junit.jar on the classpath - and here's a quick way to do it:

  1. Make sure you have a source folder (e.g. test) marked as a Test Root.

  2. Create a test, for example like this:

    public class MyClassTest {
        @Test
        public void testSomething() {
    
        }
    }
    
  3. Since you haven't configured junit.jar (yet), the @Test annotation will be marked as an error (red), hit f2 to navigate to it.

  4. Hit alt-enter and choose Add junit.jar to the classpath

There, you're done! Right-click on your test and choose Run 'MyClassTest' to run it and see the test results.

Maven Note: Altervatively, if you're using maven, at step 4 you can instead choose the option Add Maven Dependency..., go to the Search for artifact pane, type junit and take whichever version (e.g. 4.8 or 4.9).