Improve strawberry.enum typing by using generics

[TimDumol]

Description

1. Using a TypeVar bound on EnumMeta instead of EnumMeta, which allows type-checkers (like pyright)
   to detect the fields of the enum being decorated. For example, for the following enum:

@strawberry.enum
class IceCreamFlavour(Enum):
    VANILLA = "vanilla"
    STRAWBERRY = "strawberry"
    CHOCOLATE = "chocolate"

Prior to this change, pyright would complain if you tried to access
IceCreamFlavour.VANILLA, since the type information of IceCreamFlavour was being
erased by the EnumMeta typing .

2. Overloading it so that type-checkers (like pyright) knows in what cases it returns a decorator
   (when it's called with keyword arguments, e.g. @strawberry.enum(name="IceCreamFlavor")),
   versus when it returns the original enum type (without keyword arguments.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Documentation

Issues Fixed or Closed by This PR

NA

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[TimDumol]

I'm not sure whether tests are necessary for this change. Please do tell me if they are -- I'm not sure how/where to put them, if so.

[botberry]

Thanks for adding the RELEASE.md file!

Here's a preview of the changelog:

---

Improve typing of @strawberry.enum() by:

1. Using a TypeVar bound on EnumMeta instead of EnumMeta, which allows
   type-checkers (like pyright) to detect the fields of the enum being
   decorated. For example, for the following enum:

@strawberry.enum
class IceCreamFlavour(Enum):
    VANILLA = "vanilla"
    STRAWBERRY = "strawberry"
    CHOCOLATE = "chocolate"

Prior to this change, pyright would complain if you tried to access
IceCreamFlavour.VANILLA, since the type information of IceCreamFlavour was
being erased by the EnumMeta typing .

2. Overloading it so that type-checkers (like pyright) knows in what cases it
   returns a decorator (when it's called with keyword arguments, e.g.
   @strawberry.enum(name="IceCreamFlavor")), versus when it returns the
   original enum type (without keyword arguments.

Here's the tweet text:

🆕 Release (next) is out! Thanks to Tim Joseph Dumol for the PR 👏

Get it here 👉 https://github.com/strawberry-graphql/strawberry/releases/tag/(next)

[BryceBeagle]

Nice! If you want to add tests, we have some mypy tests under tests/mypy:
https://github.com/strawberry-graphql/strawberry/blob/main/tests/mypy/test_enum.yml

[codecov]

Codecov Report

Merging #1568 (28f9de2) into main (c9ad942) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1568   +/-   ##
=======================================
  Coverage   98.11%   98.11%           
=======================================
  Files         130      130           
  Lines        4467     4468    +1     
  Branches      758      758           
=======================================
+ Hits         4383     4384    +1     
  Misses         44       44           
  Partials       40       40           

[TimDumol]

Nice! If you want to add tests, we have some mypy tests under tests/mypy: https://github.com/strawberry-graphql/strawberry/blob/main/tests/mypy/test_enum.yml

Added a pair of tests for it! It was hard to find a failing test, since mypy (unlike pyright, which is why I noticed this issue in VSCode) seems to have some special-inference for decorators.

[patrick91]

@TimDumol this looks awesome! I'm going to add a test for Pyright too if you don't mind 😊

[patrick91]

Great improvement! <3

[botberry]

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