feat(eslint-plugin): [member-ordering] add support for grouping readonly fields

[IronGeek]

PR Checklist

• Addresses an existing open issue: fixes [member-ordering] separating readonly members is not supported #1063
• That issue was marked as accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

This PR introduces new member attribute/type/Kind: readonly-field, a superset of field, which denotes all fields with readonly modifiers. This makes it possible to group/ sort fields based on their readonly modifiers and optionally with their Accessibility, and or Scope too.

Like other member types, readonly-field can also be joined with accessibility and scope attributes to create more specific type; the following is the complete combination of readonly-field with Scope and Accessibility introduced in this PR:

"readonly-field"
"public-readonly-field"
"public-decorated-readonly-field"
"decorated-readonly-field"
"static-readonly-field"
"public-static-readonly-field"
"instance-readonly-field"
"public-instance-readonly-field"
"abstract-readonly-field"
"public-abstract-readonly-field"
"protected-readonly-field"
"protected-decorated-readonly-field"
"protected-static-readonly-field"
"protected-instance-readonly-field"
"protected-abstract-readonly-field"
"private-readonly-field"
"private-decorated-readonly-field"
"private-static-readonly-field"
"private-instance-readonly-field"
"#private-readonly-field"
"#private-static-readonly-field"
"#private-instance-readonly-field"

For example, with this configuration the following code would be treated as valid:

{
  "rules": {
    "@typescript-eslint/member-ordering": [
      "error", { 
        "default": [
            "decorated-readonly-field",
            ["public-readonly-field", "readonly-field"]
            "protected-readonly-field",
            "private-readonly-field",
            "abstract-readonly-field",
            "field"
        ] 
      }
    ]
  }
}

abstract class Foo {
  @Dec public readonly DA: string;
  @Dec protected readonly DB: string;
  @Dec private readonly DC: string;

  public static readonly SA: string;
  public readonly IA: string;
  static readonly #SD: string;
  readonly #ID: string;

  protected static readonly SB: string;
  protected readonly IB: string;

  private static readonly SC: string;
  private readonly IC: string;

  public abstract readonly AA: string;
  protected abstract readonly AB: string;

  public RA: string;
  RB: string;
  private RC: string;
  #RD: string;
}

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✅ Successfully ran 31 targets

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• Node 18 - nx test ast-spec
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• Node 14 - nx test visitor-keys --coverage=false
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• Node 18 - nx test eslint-plugin-internal
• Node 14 - nx test type-utils --coverage=false
• Node 18 - nx run-many --target=build --parallel --exclude website
• Node 14 - nx run-many --target=build --parallel --exclude website
• Node 14 - nx test utils --coverage=false
• Node 14 - nx run-many --target=build --parallel --exclude website
• Node 14 - nx run-many --target=build --parallel --exclude website
• Node 14 - nx test scope-manager --coverage=false
• Node 14 - nx run-many --target=build --parallel --exclude website
• Node 14 - nx test parser --coverage=false
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• Node 14 - nx test eslint-plugin-internal --coverage=false
• Node 14 - nx run-many --target=build --parallel --exclude website
• Node 14 - nx test ast-spec --coverage=false
• Node 14 - nx run-many --target=build --parallel --exclude website
• Node 14 - nx run-many --target=build --parallel --exclude website
• nx run-many --target=build --parallel --exclude website
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[typescript-eslint]

Thanks for the PR, @IronGeek!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

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[codecov]

Codecov Report

Merging #6349 (9f2e32c) into main (36ef0e1) will increase coverage by 2.65%.
The diff coverage is 100.00%.

❗ Current head 9f2e32c differs from pull request most recent head 534ac14. Consider uploading reports for the commit 534ac14 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6349      +/-   ##
==========================================
+ Coverage   88.62%   91.28%   +2.65%     
==========================================
  Files         382      366      -16     
  Lines       12883    12461     -422     
  Branches     3787     3656     -131     
==========================================
- Hits        11418    11375      -43     
+ Misses       1124      772     -352     
+ Partials      341      314      -27     

Flag	Coverage Δ
unittest	91.28% <100.00%> (+2.65%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...ackages/eslint-plugin/src/rules/member-ordering.ts	96.41% <100.00%> (+0.27%)	⬆️

... and 56 files with indirect coverage changes

[JoshuaKGoldberg]

A good start - thanks for getting this PR up! 🙌

Requesting changes on more test coverage & handling index signatures.

Aside: this rule gets more complicated and hard to deal with in every PR. But I don't see a way around it 😞. This comment isn't actionable and you can ignore my sadness. I'm just ... musing.

[JoshuaKGoldberg]

Whew, looks good to me! Thanks @IronGeek! 🙌

In theory one might want something like readonly-method, for cases like { readonly A: () => void }. But that can be a feature add if requested after this PR. The rule is (and already was) complex enough as it is.

[JoshuaKGoldberg]

Btw, sorry for the month-long wait time. This fell off my radar. After the v6 release I'm hopeful we can work on #6033 as a process improvement so it doesn't happen again.