Substitute.ForPartsOf() usage -- or Alternative?

[CleveSteve]

I have a method (MethodA) I'm trying to test (of course) and I'd like to substitute a method (MethodC) that is called inside of the method (MethodA) being tested like this...

public async MethodA(CustomClass myInfo, bool myBool)
{
    ... await stuff
    paramVal1 = MethodB(paramVal1, myInfo, myBool);
    ...morestuff
}

public DifferentCustomClass MethodB(DifferentCustomClass paramVal1, CustomClass myInfo, bool myBool)
{
    ...stuff
    paramVal1.PropertyZ = MethodC(myInfo, myBool);
    ...stuff
    return paramVal1;
}

Methods A, B, and C are all in the same class.

Is there any way I can use NSubstitute to give a .Returns(value) for MethodC when testing MethodA? I tried Substitute.ForPartsOf with .Configure().MethodC(val1, val2).Returns(val0) with and without .When(x => x.MethodC(val1, val2)).DoNotCallBase() to no avail.

Is it clear what I am trying to do here? Is there a way this can be implemented in NSubstitute? Thanks.

[CleveSteve]

never mind... I realized I'm trying to substitute something that is non-virtual anyways... I've gotta just add to the constructor... ugh. Great tool though, thank you.

[dtchepak]

@CleveSteve Glad you got it sorted. If you need more info try the partial subs documentation.

Another option rather than a partial sub (which calls base implementations by default), is using a normal sub and opting-in to calling base on some members:

public class Example
{
    public virtual string Repeat(string s, int times) {
        return String.Join(" ", Enumerable.Repeat(s, times));
    }

    public virtual string Hi(string name) => $"Hi {name}";
}

[Fact]
public void Sample() {
    var sub = Substitute.For<Example>();
    sub.Repeat("", 0).ReturnsForAnyArgs(x => "stub");
    sub.WhenForAnyArgs(x => x.Hi("")).CallBase();

    var resultFromCallingBase = sub.Hi("World");
    var stubbedResult = sub.Repeat("asfd", 42);

    Assert.Equal(resultFromCallingBase, "Hi World");
    Assert.Equal(stubbedResult, "stub");
}

Sometimes that's easier than using DoNotCallBase() on calls.

[CleveSteve]

Very Cool! Missed that option somehow. Thanks for the reply.