Exception when file name is null

[ekisielinski]

If method signature allows null string, why it throws exception?

MimeTypes/src/MimeTypes/MimeTypes.cs.pp

Line 1057 in d1e9e37

public static string GetMimeType(string? fileName)

[khellang]

Umm. Good catch! @gfoidl I assume this shouldn't be nullable? 🤔

[ekisielinski]

It depends on your design. Usually methods like TrySomething allows nulls. GetMimeType should throw ArgumentNullException for null string (because string supports Null Object Pattern - string.Empty). So I think you should remove ? from method signature.

[gfoidl]

Yeah, @ekisielinski is correct. We should remove the ? when null is validated and an ArgumentNullException thrown, so that the compilers knows that null isn't "tolerated".
For the Try-method null is allowed, so here the ? is correct.

Sorry, that's my fault. My brain was at a preview-stage of nullability and didn't update to the release along the way with updated guidlines on how to annotate...

[khellang]

Closed with 5d4e0de

[khellang]

v2.0.2 is now on NuGet 🙌