How to unit test side effecting logic

Question

I have a following code

public class Component extend Framework {
  private Integer someInt;  
  private String someString;    
  public Integer getSomeInt() {
    return someInt;
  }    
  public String getSomeString() {
    return someString;
  }
  public void activate() {
     Integer tempInt = (Integer)getProperties("key"); // From Framework
     if (tempInt == null) {
         tempInt = (Integer)getRequest().getProperties("key"); // From Framework        
     }

     if(tempInt == null)
        tempInt = (Integer)getBind().getProperties("key"); // From Frameowrk 
     someString = makeServiceCall("http://.....?key=tempInt");
  }
}

Basically activate() method is called by the framework in order to access internal state of the framework to construct Component object. activate() is sort of like a setter for the Component object. If I were to unit test the code above, what would be the best way to do it without having to have framework running?

One way would be to mock out Component class and stub the super.getProperties... calls, however if we mock the class in question, what is the point of testing to begin with?

Answer 1

I will show how to test one edge case

void testServiceCallWithNoKeyPropertyFound() {
  Component componentUnderTest = new Component() {
    Integer getProperties(String key) {
       return null; // property should not be found
    }

    Request getRequest() {
      return new Request(...); //this request should not contain a property named "key", 
    }

    Bind getBind() {
      return new Bind(...); //this bind should not contain a property named "key"
    }

    String makeServiceCall(String url) {
      if (url.endsWith("null")) {
        return success;
      }
      throw new AssertionError("expected url ending with null, but was " + url);
    }

  };
  componentUnderTest.activate();
  assertThat(componentUnderTest.getSomeString(), equalTo("success"));
}

Using Mockito (spys) can make this example much more concise. But this would hide the principles how to design the test.

There are some more edge cases:

void testServiceCallWithPropertyFoundInComponent() ...
void testServiceCallWithPropertyFoundInRequest() ...
void testServiceCallWithPropertyFoundInBind() ...