Junit testing forcing exception

Question

I have the following method:

public Object method(){
 try
 {
      privatevoidmethod1();
      privatevoidmethod2();
 }
 catch(Exception e)
 {
      Log.debug(e);
 }
  return object;
}

How do I force the exception so I can test the debug call?

Answer 1

Leaving aside how you'd test the debug call, you'd normally trigger an exception by providing suitable inputs such that an exception would be created/thrown. If that's not suitable, the alternative is to provide a substitute (mocked) component that has been configured/written to throw an exception e.g.

public MyClass(MyInjectedComponent component) {
   this.component = component;
}

and you'd provide for your test an implementation of MyInjectedComponent that will throw an exception (for testing purposes). The approach of injecting components into other components is called dependency injection and worth investigating.

I'd normally use a mocking framework for this (e.g. Mockito or similar). However a trivial implementation of the above could be:

public class MyImplementationForTesting extends MyInjectedComponent {
   public void method() throws Exception {
      throw new Exception();
   }
}