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feat(eslint-plugin): [interface-name-prefix, class-name-casing] Add allowUnderscorePrefix option to support private declarations (#790)
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‎packages/eslint-plugin/docs/rules/class-name-casing.md

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Original file line numberDiff line numberDiff line change
@@ -5,6 +5,17 @@ This rule enforces PascalCased names for classes and interfaces.
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## Rule Details
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This rule aims to make it easy to differentiate classes from regular variables at a glance.
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The `_` prefix is sometimes used to designate a private declaration, so the rule also supports a name
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that might be `_Example` instead of `Example`.
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## Options
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This rule has an object option:
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- `"allowUnderscorePrefix": false`: (default) does not allow the name to have an underscore prefix
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- `"allowUnderscorePrefix": true`: allows the name to optionally have an underscore prefix
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## Examples
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Examples of **incorrect** code for this rule:
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@@ -16,6 +27,8 @@ class Another_Invalid_Class_Name {}
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var bar = class invalidName {};
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interface someInterface {}
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class _InternalClass {}
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```
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Examples of **correct** code for this rule:
@@ -28,6 +41,9 @@ export default class {}
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var foo = class {};
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interface SomeInterface {}
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/* eslint @typescript-eslint/class-name-casing: { "allowUnderscorePrefix": true } */
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class _InternalClass {}
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```
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## When Not To Use It

‎packages/eslint-plugin/docs/rules/interface-name-prefix.md

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@@ -1,29 +1,50 @@
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# Require that interface names be prefixed with `I` (interface-name-prefix)
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It can be hard to differentiate between classes and interfaces.
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Prefixing interfaces with "I" can help telling them apart at a glance.
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Interfaces often represent important software contracts, so it can be helpful to prefix their names with `I`.
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The unprefixed name is then available for a class that provides a standard implementation of the interface.
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Alternatively, the contributor guidelines for the TypeScript repo suggest
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[never prefixing](https://github.com/Microsoft/TypeScript/wiki/Coding-guidelines#names) interfaces with `I`.
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## Rule Details
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This rule enforces consistency of interface naming prefix conventions.
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This rule enforces whether or not the `I` prefix is required for interface names.
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The `_` prefix is sometimes used to designate a private declaration, so the rule also supports a private interface
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that might be named `_IAnimal` instead of `IAnimal`.
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## Options
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This rule has a string option.
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This rule has an object option:
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- `"never"` (default) disallows all interfaces being prefixed with `"I"`
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- `"always"` requires all interfaces be prefixed with `"I"`
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- `{ "prefixWithI": "never" }`: (default) disallows all interfaces being prefixed with `"I"` or `"_I"`
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- `{ "prefixWithI": "always" }`: requires all interfaces be prefixed with `"I"` (but does not allow `"_I"`)
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- `{ "prefixWithI": "always", "allowUnderscorePrefix": true }`: requires all interfaces be prefixed with
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either `"I"` or `"_I"`
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For backwards compatibility, this rule supports a string option instead:
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- `"never"`: Equivalent to `{ "prefixWithI": "never" }`
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- `"always"`: Equivalent to `{ "prefixWithI": "always" }`
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## Examples
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### never
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TypeScript suggests [never prefixing](https://github.com/Microsoft/TypeScript/wiki/Coding-guidelines#names) interfaces with "I".
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**Configuration:** `{ "prefixWithI": "never" }`
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The following patterns are considered warnings:
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```ts
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interface IAnimal {
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name: string;
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}
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interface IIguana {
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name: string;
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}
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interface _IAnimal {
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name: string;
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}
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```
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The following patterns are not warnings:
@@ -32,16 +53,30 @@ The following patterns are not warnings:
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interface Animal {
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name: string;
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}
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interface Iguana {
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name: string;
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}
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```
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### always
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**Configuration:** `{ "prefixWithI": "always" }`
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The following patterns are considered warnings:
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```ts
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interface Animal {
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name: string;
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}
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interface Iguana {
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name: string;
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}
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interface _IAnimal {
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name: string;
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}
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```
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The following patterns are not warnings:
@@ -50,6 +85,42 @@ The following patterns are not warnings:
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interface IAnimal {
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name: string;
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}
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interface IIguana {
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name: string;
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}
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```
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### always and allowing underscores
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**Configuration:** `{ "prefixWithI": "always", "allowUnderscorePrefix": true }`
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The following patterns are considered warnings:
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```ts
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interface Animal {
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name: string;
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}
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interface Iguana {
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name: string;
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}
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```
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The following patterns are not warnings:
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```ts
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interface IAnimal {
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name: string;
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}
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interface IIguana {
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name: string;
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}
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interface _IAnimal {
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name: string;
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}
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```
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## When Not To Use It

‎packages/eslint-plugin/src/rules/class-name-casing.ts

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@@ -4,7 +4,14 @@ import {
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} from '@typescript-eslint/experimental-utils';
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import * as util from '../util';
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7-
export default util.createRule({
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type Options = [
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{
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allowUnderscorePrefix?: boolean;
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},
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];
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type MessageIds = 'notPascalCased';
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export default util.createRule<Options, MessageIds>({
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name: 'class-name-casing',
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meta: {
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type: 'suggestion',
@@ -16,16 +23,31 @@ export default util.createRule({
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messages: {
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notPascalCased: "{{friendlyName}} '{{name}}' must be PascalCased.",
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},
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schema: [],
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schema: [
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{
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type: 'object',
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properties: {
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allowUnderscorePrefix: {
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type: 'boolean',
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default: false,
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},
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},
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additionalProperties: false,
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},
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],
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},
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defaultOptions: [],
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create(context) {
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defaultOptions: [{ allowUnderscorePrefix: false }],
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create(context, [options]) {
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/**
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* Determine if the identifier name is PascalCased
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* @param name The identifier name
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*/
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function isPascalCase(name: string): boolean {
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return /^[A-Z][0-9A-Za-z]*$/.test(name);
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if (options.allowUnderscorePrefix) {
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return /^_?[A-Z][0-9A-Za-z]*$/.test(name);
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} else {
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return /^[A-Z][0-9A-Za-z]*$/.test(name);
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}
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}
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/**

‎packages/eslint-plugin/src/rules/interface-name-prefix.ts

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@@ -1,8 +1,43 @@
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import * as util from '../util';
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3-
type Options = ['never' | 'always'];
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type ParsedOptions =
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| {
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prefixWithI: 'never';
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}
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| {
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prefixWithI: 'always';
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allowUnderscorePrefix: boolean;
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};
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type Options = [
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| 'never'
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| 'always'
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| {
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prefixWithI?: 'never';
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}
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| {
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prefixWithI: 'always';
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allowUnderscorePrefix?: boolean;
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},
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];
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type MessageIds = 'noPrefix' | 'alwaysPrefix';
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/**
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* Parses a given value as options.
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*/
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export function parseOptions([options]: Options): ParsedOptions {
29+
if (options === 'always') {
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return { prefixWithI: 'always', allowUnderscorePrefix: false };
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}
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if (options !== 'never' && options.prefixWithI === 'always') {
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return {
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prefixWithI: 'always',
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allowUnderscorePrefix: !!options.allowUnderscorePrefix,
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};
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}
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return { prefixWithI: 'never' };
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}
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export default util.createRule<Options, MessageIds>({
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name: 'interface-name-prefix',
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meta: {
@@ -21,13 +56,46 @@ export default util.createRule<Options, MessageIds>({
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},
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schema: [
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{
24-
enum: ['never', 'always'],
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oneOf: [
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{
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enum: [
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// Deprecated, equivalent to: { prefixWithI: 'never' }
63+
'never',
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// Deprecated, equivalent to: { prefixWithI: 'always', allowUnderscorePrefix: false }
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'always',
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],
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},
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{
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type: 'object',
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properties: {
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prefixWithI: {
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type: 'string',
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enum: ['never'],
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},
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},
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additionalProperties: false,
77+
},
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{
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type: 'object',
80+
properties: {
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prefixWithI: {
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type: 'string',
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enum: ['always'],
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},
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allowUnderscorePrefix: {
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type: 'boolean',
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},
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},
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required: ['prefixWithI'], // required to select this "oneOf" alternative
90+
additionalProperties: false,
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},
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],
2593
},
2694
],
2795
},
28-
defaultOptions: ['never'],
29-
create(context, [option]) {
30-
const never = option !== 'always';
96+
defaultOptions: [{ prefixWithI: 'never' }],
97+
create(context, [options]) {
98+
const parsedOptions = parseOptions([options]);
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32100
/**
33101
* Checks if a string is prefixed with "I".
@@ -41,21 +109,42 @@ export default util.createRule<Options, MessageIds>({
41109
return /^I[A-Z]/.test(name);
42110
}
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112+
/**
113+
* Checks if a string is prefixed with "I" or "_I".
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* @param name The string to check
115+
*/
116+
function isPrefixedWithIOrUnderscoreI(name: string): boolean {
117+
if (typeof name !== 'string') {
118+
return false;
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}
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return /^_?I[A-Z]/.test(name);
122+
}
123+
44124
return {
45125
TSInterfaceDeclaration(node): void {
46-
if (never) {
47-
if (isPrefixedWithI(node.id.name)) {
126+
if (parsedOptions.prefixWithI === 'never') {
127+
if (isPrefixedWithIOrUnderscoreI(node.id.name)) {
48128
context.report({
49129
node: node.id,
50130
messageId: 'noPrefix',
51131
});
52132
}
53133
} else {
54-
if (!isPrefixedWithI(node.id.name)) {
55-
context.report({
56-
node: node.id,
57-
messageId: 'alwaysPrefix',
58-
});
134+
if (parsedOptions.allowUnderscorePrefix) {
135+
if (!isPrefixedWithIOrUnderscoreI(node.id.name)) {
136+
context.report({
137+
node: node.id,
138+
messageId: 'alwaysPrefix',
139+
});
140+
}
141+
} else {
142+
if (!isPrefixedWithI(node.id.name)) {
143+
context.report({
144+
node: node.id,
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messageId: 'alwaysPrefix',
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});
147+
}
59148
}
60149
}
61150
},

‎packages/eslint-plugin/tests/rules/class-name-casing.test.ts

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@@ -14,6 +14,10 @@ ruleTester.run('class-name-casing', rule, {
1414
sourceType: 'module',
1515
},
1616
},
17+
{
18+
code: 'class _NameWithUnderscore {}',
19+
options: [{ allowUnderscorePrefix: true }],
20+
},
1721
'var Foo = class {};',
1822
'interface SomeInterface {}',
1923
'class ClassNameWithDigit2 {}',
@@ -50,6 +54,20 @@ ruleTester.run('class-name-casing', rule, {
5054
},
5155
],
5256
},
57+
{
58+
code: 'class _NameWithUnderscore {}',
59+
errors: [
60+
{
61+
messageId: 'notPascalCased',
62+
data: {
63+
friendlyName: 'Class',
64+
name: '_NameWithUnderscore',
65+
},
66+
line: 1,
67+
column: 7,
68+
},
69+
],
70+
},
5371
{
5472
code: 'var foo = class {};',
5573
errors: [

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