Wsrtjtyk

I am testing my Java program with JUnit.
The program includes some JavaFX GUI interface and other logging code. However, during testing, I don't want these to be tested. Is there any way to switch the code between testing and development?

The description can be abstract, I'll use an example:

public class Helloworld {



    /**

     * @param args the command line arguments

     */

    public static int greetingCnt = 0;



    public static void main(String args) {

        Helloworld helloword = new Helloworld();

        helloword.greetWorld();

        helloword.greetWorld();

        helloword.greetWorld();

        System.out.println("Greating count: " + greetingCnt);

    }



    public void greetWorld() {

        System.out.println("Hello World!");

        ++greetingCnt;

        //some other computation...

    }



}

In this example, if I only want to test the correct number of greetingCnt but not want to have anything printed or any extra computation to be performed. But during actual program execution, there is no influence on the function of the program. May I know if there is any way to do it?

Thank you!

It is impossible without additional effort from you.

Computer simply have no way to tell which computation affect what.

You can turn off specific features like printing to console by replacing default PrintWriter, but there is no generic solution.

For your specific case : you could use PowerMock in order to mock System.out, but the be honest I ignore the whole side effects it might have.

More generally : what you are looking for is called Mock object, and basically allows an instance of an Object to do nothing be the just minimum to run through your code.

For your case, mocking System.out would allow you to run through the calls to System.out.println() without actually calling those.
So as a result, your code would execute as if it was :

public class Helloworld {



/**

 * @param args the command line arguments

 */

public static int greetingCnt = 0;



public static void main(String args) {

    Helloworld helloword = new Helloworld();

    helloword.greetWorld();

    helloword.greetWorld();

    helloword.greetWorld();

    // System.out.println("Greating count: " + greetingCnt);

}



public void greetWorld() {

    // System.out.println("Hello World!");

    ++greetingCnt;

    //some other computation...

}

I could go further in explaining how it really occurs, but I guess this is enough for your answer. If you are curious, you could look at runtime execution of your tests to inspect the real type of your mocked objects.

You would first need to make your Java program configurable.

One way to do this is using Java property files. You can then use specific properties to disable parts of your program.

During testing you can then use one property file, and during normal execution another.

The property file is typically a resource on the Java class path. Then you can run the tests with a classpath containing the property files describing the test configuration.