Add support for intersection types/interfaces

[rvetere]

This change adds support for complex union interfaces like the following:

import { MyType } from 'MyType';
import { MySecondType } from 'MySecondType';
type SuperType = { name: string } & (MyType | MySecondType);

const x: SuperType = {};

Expected result would be something like:

{
  "elements": [
    {
      "key": "name",
      "value": {
        "name": "string",
        "required": true,
      },
    },
    {
      "key": "a",
      "value": {
        "name": "number",
        "required": true,
      },
    },
    {
      "key": "b",
      "value": {
        "name": "string",
        "required": false,
      },
    },
  ],
  "name": "intersection",
  "raw": "{ name: string } & (MyType | MySecondType)",
}

I have added a test to address this, and i was fighting pretty hard with the existing types (chat gpt was a big help) - but i'm pretty sure there is room for improvement, help would be appreciated :)

TODOS

• Modify "handleTSIntersectionType" in "getTSType" to fully resolve all involved types
• Add new "handleTSParenthesizedType" to "getTSType" to fully resolve all involved types
• Add new test for "getTSType", "deep resolve intersection types"
• Get rid of "any" typings and stupid typeguards in "getTSType" i have added to "make it work"
• Support TS union types in "codeTypeHelper"
• Adjust existing test "does not support union proptypes" into "does support union proptypes"
• Add tests for the new utility "mergeTSIntersectionTypes"
• Create changeset, this is definitely a new version

Fixes #914

[changeset-bot]

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Latest commit: ae337cc

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[danez]

Thanks a lot, i will try to find some time to review this in the coming weeks. Probably will take a little while.

[rvetere]

Hey i needed to convert the PR to a draft for the moment. I realized that the codeHelper needs similar modifications to support union types and i'm not done yet. And i'm pretty sure i have not tested all possible cases yet - i want to extend the tests to fully cover that ;-)

[rvetere]

Hi @danez, i'm happy now with the output produced - with these changes in place, our team would be unblocked to finally migrate from react-docgen-typescript to react-docgen. But i'm sure there are still missing pieces. For one, the changeset. I think we should create a new minor version for that, what do you think?

The other thing is the typing - i'm not happy with that what i've done in getTSType. Another interesting find for me - after adding the support of "intersection types" in getTSType, i still got the same output from the parsed component. I had to add the same kind of changes to the codeTypeHandler too until i've got the output i want. So i guess, my extension of getTSType was somewhat useless? :D

And finally, please help me out with flow types - i have never really worked with flow typing and i already failed trying to setup an example repo for that. For now i'm going to publish a fork for this package with all changes so we can test it thoroughly in our e-commerce platform.