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

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@@ -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:
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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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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',
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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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import * as util from '../util';
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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 {
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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: {
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},
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schema: [
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{
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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' }
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'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,
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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: ['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
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additionalProperties: false,
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},
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],
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},
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],
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},
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defaultOptions: ['never'],
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create(context, [option]) {
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const never = option !== 'always';
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defaultOptions: [{ prefixWithI: 'never' }],
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create(context, [options]) {
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const parsedOptions = parseOptions([options]);
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/**
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* Checks if a string is prefixed with "I".
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return /^I[A-Z]/.test(name);
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}
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/**
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* Checks if a string is prefixed with "I" or "_I".
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* @param name The string to check
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*/
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function isPrefixedWithIOrUnderscoreI(name: string): boolean {
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if (typeof name !== 'string') {
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return false;
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}
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return /^_?I[A-Z]/.test(name);
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}
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return {
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TSInterfaceDeclaration(node): void {
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if (never) {
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if (isPrefixedWithI(node.id.name)) {
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if (parsedOptions.prefixWithI === 'never') {
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if (isPrefixedWithIOrUnderscoreI(node.id.name)) {
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context.report({
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node: node.id,
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messageId: 'noPrefix',
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});
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}
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} else {
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if (!isPrefixedWithI(node.id.name)) {
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context.report({
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node: node.id,
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messageId: 'alwaysPrefix',
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});
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if (parsedOptions.allowUnderscorePrefix) {
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if (!isPrefixedWithIOrUnderscoreI(node.id.name)) {
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context.report({
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node: node.id,
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messageId: 'alwaysPrefix',
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});
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}
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} else {
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if (!isPrefixedWithI(node.id.name)) {
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context.report({
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node: node.id,
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messageId: 'alwaysPrefix',
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});
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}
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}
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}
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},

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

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@@ -14,6 +14,10 @@ ruleTester.run('class-name-casing', rule, {
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sourceType: 'module',
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},
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},
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{
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code: 'class _NameWithUnderscore {}',
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options: [{ allowUnderscorePrefix: true }],
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},
1721
'var Foo = class {};',
1822
'interface SomeInterface {}',
1923
'class ClassNameWithDigit2 {}',
@@ -50,6 +54,20 @@ ruleTester.run('class-name-casing', rule, {
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},
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],
5256
},
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{
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code: 'class _NameWithUnderscore {}',
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errors: [
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{
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messageId: 'notPascalCased',
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data: {
63+
friendlyName: 'Class',
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name: '_NameWithUnderscore',
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},
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line: 1,
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column: 7,
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},
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],
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},
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{
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code: 'var foo = class {};',
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errors: [

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