The Decorators proposal does not have enough tests

[nicolo-ribaudo]

There are only syntax tests for the decorators proposal, and no behavior tests: https://github.com/search?q=repo%3Atc39%2Ftest262+path%3Adecorator+path%3A%2F%5Etest%5C%2Flanguage%5C%2F%2F&type=code

Babel has been passing all test262 decorators tests for a while, but we still found a lot of bugs in our implementation:

• [Bug]: Stage 3 decorators behavior differences from TypeScript babel/babel#16117
• [Bug]: decorators 2023-05: addInitializer runs initializer at the wrong time babel/babel#16188
• fix: Class decorator correctly passes return value babel/babel#16199
• fix: Class decorator ctx.kind is wrong babel/babel#16180
• Fix protoInit call injection timing babel/babel#16235

I'm opening this issue because I saw that there is no issue or PR about that proposal, and in our new stages process it probably wouldn't qualify for Stage 3.

EDIT: Something else interesting to test:

• Reduce helper size for decorator 2023-11 babel/babel#16263 (comment)
• [Decorators] Missing error when calling addInitializer after that the decorator is done microsoft/TypeScript#57300

[nicolo-ribaudo]

Also, there are some very good tests by @evanw at https://github.com/evanw/decorator-tests

[pzuraq]

I’m planning on working on this in the next few weeks