JustMock - 检查传递的方法参数的值

Question

I use JustMock framework and have the following assertion:

Mock.Assert(() => activityListenerMock.PeriodPassed(
  Arg.Matches<Period>(e => e.Length == expectedLength)));

It fails with cryptic message:

Occurrence expectation failed. Expected at least 1 call. Calls so far: 0

How can I get better message. I want to know with what value it was called.

Method is actually called but with wrong argument because when I change assertion to following it passes:

Mock.Assert(() => activityListenerMock.PeriodPassed(
  Arg.IsAny<Period>()));

Answer 1

One way to see what argument was passed to PeriodPassed is to use JustMock's DebugView

Place DebugView.IsTraceEnabled = true; at the beginning of the test and add DebugView.CurrentState to the watch. Towards the end you will see something to the tune of this: Invocations: (ByRef ...).PeriodPassed("period value will go here") called 1 time; (signature: ...) Invocations: (ByRef ...).PeriodPassed("period value will go here") called 1 time; (signature: ...)

The period value will be shown in the Invocations list.

Another way to do this, is to extract the matcher into a separate lambda and use a breakpoint: Predicate<Period> matcher = e => e.Length == expectedLength; Mock.Assert(() => activityListenerMock.PeriodPassed( Arg.Matches<Period>(e => matcher(e)))); Predicate<Period> matcher = e => e.Length == expectedLength; Mock.Assert(() => activityListenerMock.PeriodPassed( Arg.Matches<Period>(e => matcher(e))));

Now you can place a breakpoint inside the predicate and check the value of the e argument. This works because now the predicate is not an expression but an actual function, so now you can debug it.

Answer 2

Just to what Stefan Dragnev wrote. I used his idea and then added logic to validate the input. If not the expected value called Assert.Fail(). Not sure if there is a better way, but this works:

Mock.Arrange(() => _uowMock.Class.Add(
    Arg.Matches<ModelClass>(x => (CheckArgs(x, updated)))))
    .DoNothing().Occurs(3);

....

protected static bool CheckArgs(ModelClass x, int y)
{
    if (x.val != y)
    {
        Assert.Fail("Houston we have a problem");
    }

    return true;
}

Answer 3

Adding additional arrange before also worked for me but it is very hacky:

Mock.Arrange(() => activityListenerMock.PeriodPassed(Arg.IsAny<Period>())).
  DoInstead((Period p) => Console.WriteLine("Actual " + p.Length+" expected "+expectedLength));

Answer 4

Ran into this same dilemma today and started expanding on Krzysztof's idea some with an extension. It's rough but functional.

public static class JustMockExtensions {
        public static FuncExpectation<T> PrintParams<T, T1>(this FuncExpectation<T> mock) {
            return mock.DoInstead<T1, T>((arg1, arg2) => {
                string message = string.Empty;
                message += Process(arg1);
                message += Process(arg2);
                Console.WriteLine(message);
            });
        }

        private static string Process<T>(T obj) {
            if (typeof(T).IsEnum) {
                return Enum.GetName(typeof(T), obj);
            }
            return obj.ToString();
        }
    }

So far using it this way allows for it be piped along in the normal flow.

Mock.Arrange(() => foo.bar(Arg.IsAny<Widget>(), Arg.IsAny<WidgetTypeEnum>()))
                .PrintParams<Widget, WidgetTypeEnum>()
                .MustBeCalled();