Fix: Optional methods are not marked as optional (fixes #206)

[Pajn]

No description provided.

[eslintbot]

LGTM

[soda0289]

I don't think you can have optional parameters defined in a class. This would only be valid when the class is declared

declare class A {
  optional?();
  required();
}

or maybe even an abstract class

abstract class A {
  public abstract optional?();
  
  public abstract required();
}

The typescript parser should throw an error not sure why its not.

[soda0289]

I could be wrong thou it seems to work on typescript playground just seems odd to me.
I should note it works when I remove the empty body required() function:

class A {
  public  optional?();
}

[Pajn]

If I understand the tests correctly optional properties are not allowed but optional methods are
https://github.com/Microsoft/TypeScript/blob/ac67b94a6ea209760bfc31d9328337a16c41a0c1/tests/cases/conformance/types/namedTypes/classWithOptionalParameter.ts
https://github.com/Microsoft/TypeScript/blob/ac67b94a6ea209760bfc31d9328337a16c41a0c1/tests/cases/conformance/types/namedTypes/optionalMethods.ts

However, non of the show errors in my editor so it seems I have stumbled upon a strange corner case 😛

[soda0289]

I never knew of that typescript feature. I think we may want to add tests for the other two cases, declare and abstract, and maybe not have a class with a required function without a body since that should be an error in typescript.

[soda0289]

I see the test case does not have a required function without a body. Never mind this should be good.

[Pajn]

ah, sorry for that. I focused on the optional part and didn't realize the example in the issue was invalid. But as you noticed, that isn't the same as the test :)

I will add one ambient/declare and one abstract class as test cases as well.

[eslintbot]

LGTM