in string parameter verifying doesn't work in some cases

[wholegroup]

moq 4.10.1

        public interface ISome
        {
            string bad(in string text);
        }

        [Test]
        public void testMoq()
        {
            var m = new Mock<ISome>();
            m.Setup(foo => foo.bad("test")).Verifiable();
            m.Object.bad("test.".TrimEnd('.')); // it doesn't work
//            m.Object.bad("test"); // it works well
            m.Verify();
        }

[stakx]

Why are you passing string using in? System.String is already a reference type, and as such will be passed by-reference anyway.

[wholegroup]

@stakx
I use in modifier to mark variables as immutable. It's kind of final in Java. Microsoft calls this 'readonly references'.

[stakx]

in was introduced to be used mostly in conjunction with value types.
Of course it's your decision to use it however you want. Just be aware that Moq has certain rules when it comes to matching by-ref arguments (which align more with how by-ref parameters are typically employed), which you'll need to follow if you want to continue using in your way.

P.S.: The reason one of your invocations is matched while the other isn't most likely has to do with string interning.

m.Object.bad("test.".TrimEnd('.')); // it doesn't work
// m.Object.bad("test"); // it works well

When using the string constant "test", both the setup and the invocation refer to the exact same string instance in both cases due to interning. When you use a string expression "test.".TrimEnd('.'), a new, distinct string object will get computed that does not reference-equal the "test" string instance. To test that theory, try calling your method with an argument string.Intern("test.".Trim('.')) and see what happens.

[wholegroup]

@stakx

Thank you for your help and fast response! I definitely used in in the wrong way.

When using the string constant "test", both the setup and the invocation refer to the exact same string instance in both cases due to interning. When you use a string expression "test.".TrimEnd('.'), a new, distinct string object will get computed that does not reference-equal the "test" string instance. To test that theory, try calling your method with an argument string.Intern("test.".Trim('.')) and see what happens.

[stakx]

Glad I could help. 😃