refactor(test): remove redundant undefined

[noritaka1166]

remove redundant undefined in test

[kettanaito]

Hi, @noritaka1166. Appreciate the suggestion here, but that undefined is not redundant as x?: string, x: string | undefined, and x?: string | undefined are three different types that produce different matching results.

In our case, we want to match three things:

• The property is not required (x?:)
• The property can be string, if defined (x?: string)
• The property can also be an explicit undefined (x?: string | undefined).

I believe the current type tests capture these scenarios well. Let me know if I missed anything. Otherwise, I will close this pull request.

[noritaka1166]

@kettanaito
Understood. I close this PR.