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Add regexp/prefer-character-class rule (#40)
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‎README.md

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@@ -95,6 +95,7 @@ The rules with the following star :star: are included in the `plugin:regexp/reco
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| [regexp/no-useless-non-greedy](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-useless-non-greedy.html) | disallow unnecessary quantifier non-greedy (`?`) | :wrench: |
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| [regexp/no-useless-range](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-useless-range.html) | disallow unnecessary range of characters by using a hyphen | :wrench: |
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| [regexp/no-useless-two-nums-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/no-useless-two-nums-quantifier.html) | disallow unnecessary `{n,m}` quantifier | :star: |
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| [regexp/prefer-character-class](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-character-class.html) | enforce using character class | :wrench: |
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| [regexp/prefer-d](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-d.html) | enforce using `\d` | :star::wrench: |
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| [regexp/prefer-plus-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-plus-quantifier.html) | enforce using `+` quantifier | :star::wrench: |
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| [regexp/prefer-quantifier](https://ota-meshi.github.io/eslint-plugin-regexp/rules/prefer-quantifier.html) | enforce using quantifier | :wrench: |

‎docs/rules/README.md

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@@ -27,6 +27,7 @@ The rules with the following star :star: are included in the `plugin:regexp/reco
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| [regexp/no-useless-non-greedy](./no-useless-non-greedy.md) | disallow unnecessary quantifier non-greedy (`?`) | :wrench: |
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| [regexp/no-useless-range](./no-useless-range.md) | disallow unnecessary range of characters by using a hyphen | :wrench: |
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| [regexp/no-useless-two-nums-quantifier](./no-useless-two-nums-quantifier.md) | disallow unnecessary `{n,m}` quantifier | :star: |
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| [regexp/prefer-character-class](./prefer-character-class.md) | enforce using character class | :wrench: |
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| [regexp/prefer-d](./prefer-d.md) | enforce using `\d` | :star::wrench: |
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| [regexp/prefer-plus-quantifier](./prefer-plus-quantifier.md) | enforce using `+` quantifier | :star::wrench: |
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| [regexp/prefer-quantifier](./prefer-quantifier.md) | enforce using quantifier | :wrench: |

‎docs/rules/prefer-character-class.md

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---
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pageClass: "rule-details"
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sidebarDepth: 0
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title: "regexp/prefer-character-class"
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description: "enforce using character class"
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---
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# regexp/prefer-character-class
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> enforce using character class
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- :exclamation: <badge text="This rule has not been released yet." vertical="middle" type="error"> ***This rule has not been released yet.*** </badge>
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- :wrench: The `--fix` option on the [command line](https://eslint.org/docs/user-guide/command-line-interface#fixing-problems) can automatically fix some of the problems reported by this rule.
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## :book: Rule Details
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This rule is aimed to use character classes instead of the disjunction of single element alternatives.
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<eslint-code-block fix>
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```js
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/* eslint regexp/prefer-character-class: "error" */
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/* ✓ GOOD */
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var foo = /[abc]/
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/* ✗ BAD */
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var foo = /a|b|c/
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```
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</eslint-code-block>
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## :wrench: Options
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Nothing.
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## :mag: Implementation
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- [Rule source](https://github.com/ota-meshi/eslint-plugin-regexp/blob/master/lib/rules/prefer-character-class.ts)
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- [Test source](https://github.com/ota-meshi/eslint-plugin-regexp/blob/master/tests/lib/rules/prefer-character-class.ts)

‎lib/rules/prefer-character-class.ts

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import type { Expression } from "estree"
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import type { RegExpVisitor } from "regexpp/visitor"
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import type {
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CapturingGroup,
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Character,
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CharacterClass,
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CharacterSet,
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Group,
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LookaroundAssertion,
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Pattern,
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} from "regexpp/ast"
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import {
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createRule,
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defineRegexpVisitor,
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fixerApplyEscape,
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getRegexpLocation,
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getRegexpRange,
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} from "../utils"
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export default createRule("prefer-character-class", {
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meta: {
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docs: {
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description: "enforce using character class",
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// TODO In the major version
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// recommended: true,
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recommended: false,
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},
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fixable: "code",
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schema: [],
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messages: {
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unexpected:
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'Unexpected the disjunction of single element alternatives. Use character class "[...]" instead.',
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},
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type: "suggestion", // "problem",
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},
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create(context) {
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const sourceCode = context.getSourceCode()
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/**
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* Create visitor
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* @param node
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*/
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function createVisitor(node: Expression): RegExpVisitor.Handlers {
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/** Verify alternatives */
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function verify(
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regexpNode:
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| Group
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| CapturingGroup
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| Pattern
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| LookaroundAssertion,
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) {
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if (regexpNode.alternatives.length <= 1) {
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return
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}
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const elements: (
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| Character
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| CharacterSet
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| CharacterClass
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)[] = []
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for (const alt of regexpNode.alternatives) {
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if (alt.elements.length !== 1) {
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return
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}
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const element = alt.elements[0]
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if (element.type === "CharacterSet") {
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if (element.kind === "any") {
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return
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}
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} else if (
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element.type !== "Character" &&
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element.type !== "CharacterClass"
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) {
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return
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}
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elements.push(element)
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}
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context.report({
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node,
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loc: getRegexpLocation(sourceCode, node, regexpNode),
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messageId: "unexpected",
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fix(fixer) {
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let replaceRange: [number, number] | null = null
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let newText = ""
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for (const element of elements) {
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const range = getRegexpRange(
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sourceCode,
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node,
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element,
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)
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if (!range) {
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return null
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}
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if (!replaceRange) {
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replaceRange = [...range]
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} else {
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replaceRange[1] = range[1]
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}
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const text =
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element.type === "CharacterClass"
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? element.raw.slice(1, -1)
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: element.raw
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if (text.startsWith("-")) {
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newText += fixerApplyEscape("\\", node)
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}
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newText += text
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}
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return fixer.replaceTextRange(
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replaceRange!,
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`[${newText}]`,
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)
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},
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})
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}
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return {
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onPatternEnter: verify,
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onGroupEnter: verify,
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onCapturingGroupEnter: verify,
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onAssertionEnter(aNode) {
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if (
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aNode.kind === "lookahead" ||
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aNode.kind === "lookbehind"
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) {
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verify(aNode)
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}
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},
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}
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}
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return defineRegexpVisitor(context, {
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createVisitor,
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})
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},
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})

‎lib/utils/rules.ts

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@@ -15,6 +15,7 @@ import noUselessExactlyQuantifier from "../rules/no-useless-exactly-quantifier"
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import noUselessNonGreedy from "../rules/no-useless-non-greedy"
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import noUselessRange from "../rules/no-useless-range"
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import noUselessTwoNumsQuantifier from "../rules/no-useless-two-nums-quantifier"
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import preferCharacterClass from "../rules/prefer-character-class"
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import preferD from "../rules/prefer-d"
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import preferPlusQuantifier from "../rules/prefer-plus-quantifier"
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import preferQuantifier from "../rules/prefer-quantifier"
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noUselessNonGreedy,
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noUselessRange,
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noUselessTwoNumsQuantifier,
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preferCharacterClass,
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preferD,
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preferPlusQuantifier,
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preferQuantifier,

‎tests/lib/rules/prefer-character-class.ts

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import { RuleTester } from "eslint"
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import rule from "../../../lib/rules/prefer-character-class"
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const tester = new RuleTester({
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parserOptions: {
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ecmaVersion: 2020,
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sourceType: "module",
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},
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})
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tester.run("prefer-character-class", rule as any, {
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valid: [
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`/regexp/`,
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`/[regexp]/`,
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`/reg|exp/`,
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String.raw`/a|b|c|\d|(d)/`,
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String.raw`/a|.|c|\d|c|[-d-f]/`,
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],
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invalid: [
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{
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code: String.raw`/a|b|c|\d/`,
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output: String.raw`/[abc\d]/`,
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errors: [
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{
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message:
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'Unexpected the disjunction of single element alternatives. Use character class "[...]" instead.',
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line: 1,
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column: 2,
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endLine: 1,
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endColumn: 10,
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},
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],
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},
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{
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code: String.raw`/(a|b|c|\d)/`,
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output: String.raw`/([abc\d])/`,
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errors: [
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{
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message:
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'Unexpected the disjunction of single element alternatives. Use character class "[...]" instead.',
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line: 1,
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column: 2,
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endLine: 1,
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endColumn: 12,
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},
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],
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},
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{
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code: String.raw`/(?:a|b|c|\d)/`,
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output: String.raw`/(?:[abc\d])/`,
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errors: [
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{
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message:
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'Unexpected the disjunction of single element alternatives. Use character class "[...]" instead.',
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line: 1,
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column: 2,
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endLine: 1,
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endColumn: 14,
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},
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],
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},
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{
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code: String.raw`/(?=a|b|c|\d)/`,
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output: String.raw`/(?=[abc\d])/`,
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errors: [
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{
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message:
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'Unexpected the disjunction of single element alternatives. Use character class "[...]" instead.',
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line: 1,
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column: 2,
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endLine: 1,
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endColumn: 14,
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},
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],
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},
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{
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code: String.raw`/(?<=a|b|c|\d)/`,
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output: String.raw`/(?<=[abc\d])/`,
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errors: [
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{
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message:
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'Unexpected the disjunction of single element alternatives. Use character class "[...]" instead.',
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line: 1,
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column: 2,
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endLine: 1,
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endColumn: 15,
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},
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],
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},
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{
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code: String.raw`/a|b|c|\d|[d-f]/`,
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output: String.raw`/[abc\dd-f]/`,
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errors: [
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'Unexpected the disjunction of single element alternatives. Use character class "[...]" instead.',
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],
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},
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{
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code: String.raw`/a|-|c|\d|c|[-d-f]/`,
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output: String.raw`/[a\-c\dc\-d-f]/`,
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errors: [
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'Unexpected the disjunction of single element alternatives. Use character class "[...]" instead.',
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],
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},
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{
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code: String.raw`/a|[.]|c|\d|c|[-d-f]/`,
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output: String.raw`/[a.c\dc\-d-f]/`,
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errors: [
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'Unexpected the disjunction of single element alternatives. Use character class "[...]" instead.',
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],
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},
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],
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})

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