Brutally simple tutorial on using JUnit4 in Intellij with Java

IntellijJUnit4.md

JUnit testing in Intellij

This is a brutally simple introduction to unit testing in Intellij

General setup

• Create a new Project
• Create a folder called "tests" in the project. It should be at the same level as "src" for this simple example.
• Click on file
  • Click on "Project Structure"
    • Click on "Modules" in the left pane
    • Click on "Sources" in the right pane
    • Select "tests"
    • On the line that starts "Mark as" select "Texts"
    • Click on Apply and OK.

Go into your Main{ } class and enter the following: (You might have a different class name) public class Main {

    public static void main(String[] args) {
          System.out.printf("%d, %d\n",0,square(0));
        System.out.printf("%d, %d\n",-1,square(-1));
        System.out.printf("%d, %d\n",1,square(1));
        System.out.printf("%d, %d\n",85,square(85));

    }
    public static int square(int number){
        return number*number;
    }
}

Right-click on Main and select "Run"

Set up the first test

• Click on the function name "square"
• hit Ctrl-Shift-T
• Select "Create New Test.."
• Change "Groovy JUnit" to JUnit4
  • Hit "Fix"
  • Hit "OK"
• Click on the check box next to "square" and hit OK.

I suggest you type the following line up with the import

import static org.junit.Assert.*;

Type the following into the class:

public class MainTest {
    @Test
    public void square() throws Exception {
         assertEquals(4,Main.square(2));
    }
}

At this point note that you have two methods called "square" in your project. One is Main.square( ... ) and the other is MainTest.square(...) If you want to simplify things, change square in TestMain to "TestSquare"

public class MainTest {
    @Test
    public void TestSquare() throws Exception {
         assertEquals(4,Math.square(2));
    }
}

Right click on the "TestMain" class. Click "Run" You should get a green bar

Notice that if you click on "Run" on the top menu and then "Run.." you have two options for what to run.