How to write custom constraint using Jmock when the method to be mocked is having multiple argument

Question

I am facing difficulty in writing Unit test case for some large code base where I have to mock a lot of classes so that I can proceed with the testing easily. I found in the API documentation of Jmock that the customeconstraint I can use is containing a method

eval(Object argo)

Which will return true if the argument is meeting the expectations.

But my method is invoked with multiple arguments. How can I evaluate the arguments and make sure that the arguments with which the method was invoked is correct. Thanks in advance.

Answer 1

Often it is sufficient to create objects that are equal to the expected parameter values:

context.checking(new Expectations() {{
  allowing(calculator).add(1, 2);
  will(returnValue(3));

  DateTime loadTime = new DateTime(12);
  DateTime fetchTime = new DateTime(14);
  allowing(reloadPolicy).shouldReload(loadTime, fetchTime);
  will(returnValue(false));
}});

JMock also provides some predefined constraints:

context.checking(new Expectations() {{
  allowing(calculator).sqrt(with(lessThan(0));
  will(throwException(new IllegalArgumentException());
}});

You also can use a custom matcher using with:

context.checking(new Expectations() {{
  DateTime loadTime = new DateTime(12);
  allowing(reloadPolicy).shouldReload(with(equal(loadTime)), with(timeGreaterThan(loadTime));
  will(returnValue(false));
}});

Here timeGreaterThan could be defined as:

public class TimeGreaterThanMatcher extends TypeSafeMatcher<DateTime> {
    private DateTime minTime;

    public TimeGreaterThanMatcher(DateTime minTime) {
        this.minTime = minTime;
    }

    public boolean matchesSafely(DateTime d) {
        return d != null && minTime.isBefore(d);
    }

    public StringBuffer describeTo(Description description) {
        return description.appendText("a DateTime greater than ").appendValue(minTime);
    }

    public static Matcher<DateTime> timeGreaterThan(DateTime minTime) {
      return new TimeGreaterThanMatcher(minTime);
    }
}

See the JMock Cookbook for more information