CODEWITHSUNDEEP
javajunitexit-codesystem.exit
Roy Sht
Roy Sht

Reputation: 123

Testing if a java program calls System.exist - without exiting Junit

I am trying to test a file processing program with Junit. In some cases, the program should print an error and finish its run. However, using "System.exit(-1)" causes the program to exit the entire Junit tests. Is there some way of avoiding it?

I can instead print the error and then return null, however I find it quite inelegant.

    private List<String> parseData(String[] args){
        if (args.length != 2){
            System.err.println(ERROR + INPUT_ERROR + "\n");
            System.exit(EXIT_CODE);

Is there a way to check if the program called "System.exit" without closing it? Thank you.

Upvotes: 2

Views: 654

Answers (2)

Aasmund Eldhuset
Aasmund Eldhuset

Reputation: 37950

While I think AdrianM's solution is the ideal one, you could also solve this with mocking.

Option one: Use a mocking framework such as PowerMock that lets you mock static methods so that you can make System.exit do nothing.

Option two: Use dependency injection and any mocking framework. Create this interface and implementing class:

public interface SystemExit {
    void exit(int code);
}

public class SystemExitImpl implements SystemExit {
    public void exit(int code) {
        System.exit(code);
    }
}

Then, make the class that contains parseData take a SystemExit as a constructor parameter and store it in a member variable (or have a setter for the member variable that lets you set it after construction). In your production code, pass a SystemExitImpl. In your test, create a mock for SystemExit and pass that instead.

Upvotes: 1

AdrianM
AdrianM

Reputation: 175

I think it's more inelegant to use System.exit to validate input parameters. Why not just throw an exception and let the caller of this method handle it ?

Upvotes: 4

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