Initial Commit

.gitignore

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+coverage
+dist

.prettierignore

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+coverage
+dist

.prettierrc.js

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+// https://prettier.io/docs/en/options.html
+module.exports = {
+  semi: false,
+  useTabs: false,
+  tabWidth: 2,
+  singleQuote: true,
+  trailingComma: 'es5',
+  bracketSpacing: true,
+  jsxBracketSameLine: true,
+  arrowParens: 'always',
+}

.vscode/settings.json

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+{
+  "editor.formatOnSave": true
+}

CHANGELOG.md

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+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## 0.0.1 - 2021-04-17
+
+### Added
+
+- added `better-dates/ban-date-mutation` rule to prevent modifying Dates

LICENSE

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+MIT License
+
+Copyright (c) 2021 Christopher Dignam
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# eslint-plugin-better-dates [![npm version](https://img.shields.io/npm/v/@typescript-eslint/eslint-plugin.svg)](https://www.npmjs.com/package/@typescript-eslint/eslint-plugin)
+
+> An ESlint plugin to prevent `Date`-related bugs.
+
+## Installation
+
+Make sure you have TypeScript and [`@typescript-eslint/parser`](https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/parser/README.md) installed:
+
+```console
+$ yarn add -D typescript @typescript-eslint/parser
+$ npm i --save-dev typescript @typescript-eslint/parser
+```
+
+Then install the plugin:
+
+```console
+$ yarn add -D eslint-plugin-better-dates
+$ npm i --save-dev eslint-plugin-better-dates
+```
+
+## Usage
+
+Add `@typescript-eslint/parser` to the `parser` field and `better-dates` to the plugins section of your `.eslintrc` configuration file, then configure the rules you want to use under the rules section.
+
+```json
+{
+  "parser": "@typescript-eslint/parser",
+  "plugins": ["better-dates"],
+  "rules": {
+    "better-dates/ban-mutation": "error"
+  }
+}
+```
+
+**Note: Make sure to use `eslint --ext .js,.ts` since by [default](https://eslint.org/docs/user-guide/command-line-interface#--ext) `eslint` will only search for `.js` files.**
+
+## Rules
+
+**Key**: :wrench: = fixable, :thought_balloon: = requires type information
+
+| Name                                                     | Description                                               | :wrench: | :thought_balloon: |
+| -------------------------------------------------------- | --------------------------------------------------------- | -------- | ----------------- |
+| [`ban-date-mutation`](./docs/rules/ban-date-mutation.md) | Bans calling methods on `Date` that will mutate the date. |          | :thought_balloon: |
+
+> Project layout and configuration modified from [`typescript-eslint/eslint-plugin`](https://github.com/typescript-eslint/typescript-eslint/tree/26d71b57fbff013b9c9434c96e2ba98c6c541259/packages/eslint-plugin).

docs/rules/ban-date-mutation.md

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+# Bans mutating dates (`ban-date-mutation`)
+
+Mutating dates can create confusing bugs. Instead, create new dates using a library like [`date-fns`](https://github.com/date-fns/date-fns).
+
+## Rule Details
+
+This rule bans methods that mutate `Date`.
+
+Banned `Date` methods:
+
+- `setDate`
+- `setFullYear`
+- `setHours`
+- `setMilliseconds`
+- `setMinutes`
+- `setMonth`
+- `setSeconds`
+- `setTime`
+- `setUTCDate`
+- `setUTCFullYear`
+- `setUTCHours`
+- `setUTCMilliseconds`
+- `setUTCMinutes`
+- `setUTCMonth`
+- `setUTCSeconds`
+- `setYear`
+
+### Examples
+
+Examples of **incorrect** code with the default options:
+
+```ts
+const expiration = new Date()
+
+const noon = expiration.setHours(12)
+const seventeenth = expiration.setDate(17)
+const twentyTen = expiration.setFullYear(2010, 05, 23)
+const thirtySeconds = expiration.setSeconds(30)
+```
+
+Examples of **correct** code with the default options:
+
+```ts
+const expiration = new Date()
+
+import setHours from 'date-fns/setHours'
+const noon = setHours(setHours, 12)
+
+import setDate from 'date-fns/setDate'
+const seventeenth = setDate(expiration, 17)
+
+import setYear from 'date-fns/setYear'
+import setMonth from 'date-fns/setMonth'
+import setDate from 'date-fns/setDate'
+const twentyTen = setDate(setMonth(setYear(expiration, 2010), 05), 23)
+
+import setSeconds from 'date-fns/setSeconds'
+const thirtySeconds = setSeconds(expiration, 30)
+```
+
+## When Not To Use It
+
+If you don't mind the risk of date mutations causing bugs in your system.

jest.config.js

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+'use strict'
+
+// @ts-check
+/** @type {import('@jest/types').Config.InitialOptions} */
+module.exports = {
+  globals: {
+    'ts-jest': {
+      isolatedModules: true,
+    },
+  },
+  testEnvironment: 'node',
+  transform: {
+    '^.+\\.tsx?$': 'ts-jest',
+  },
+  testRegex: './tests/.+\\.test\\.ts$',
+  collectCoverage: false,
+  collectCoverageFrom: ['src/**/*.{js,jsx,ts,tsx}'],
+  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
+  coverageReporters: ['text-summary', 'lcov'],
+}

package.json

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+{
+  "name": "eslint-plugin-better-dates",
+  "version": "0.0.1",
+  "description": "ESLint plugin to prevent Date-related bugs.",
+  "keywords": [
+    "eslint",
+    "eslintplugin",
+    "eslint-plugin",
+    "typescript"
+  ],
+  "engines": {
+    "node": "^10.12.0 || >=12.0.0"
+  },
+  "files": [
+    "dist",
+    "docs",
+    "package.json",
+    "README.md",
+    "LICENSE"
+  ],
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/chdsbd/eslint-plugin-better-dates.git"
+  },
+  "bugs": {
+    "url": "https://github.com/chdsbd/eslint-plugin-better-dates/issues"
+  },
+  "license": "MIT",
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "scripts": {
+    "build": "tsc -b tsconfig.json",
+    "clean": "tsc -b tsconfig.json --clean",
+    "format": "prettier --write \"./**/*.{ts,js,json,md}\"",
+    "lint": "eslint . --ext .js,.ts --ignore-path ../../.eslintignore",
+    "test": "jest --coverage",
+    "typecheck": "tsc -p tsconfig.json --noEmit"
+  },
+  "dependencies": {
+    "@typescript-eslint/experimental-utils": "^4.22.0"
+  },
+  "devDependencies": {
+    "@types/node": "^14.14.41",
+    "@types/prettier": "*",
+    "@typescript-eslint/parser": "^4.22.0",
+    "eslint": "^7.24.0",
+    "jest": "^26.6.3",
+    "prettier": "*",
+    "ts-jest": "^26.5.5",
+    "typescript": "*"
+  },
+  "peerDependencies": {
+    "@typescript-eslint/parser": "^4.0.0",
+    "eslint": "^5.0.0 || ^6.0.0 || ^7.0.0"
+  },
+  "peerDependenciesMeta": {
+    "typescript": {
+      "optional": true
+    }
+  }
+}

src/index.ts

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+import rules from './rules'
+
+export = {
+  rules,
+}

src/rules/ban-date-mutation.ts

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+import * as ts from 'typescript'
+import * as util from '../util'
+
+export type MessageIds = 'banDateMutation'
+
+const disallowedDateMethods = new Set([
+  'setDate',
+  'setFullYear',
+  'setHours',
+  'setMilliseconds',
+  'setMinutes',
+  'setMonth',
+  'setSeconds',
+  'setTime',
+  'setUTCDate',
+  'setUTCFullYear',
+  'setUTCHours',
+  'setUTCMilliseconds',
+  'setUTCMinutes',
+  'setUTCMonth',
+  'setUTCSeconds',
+  'setYear',
+])
+
+const methodToDateFns: Record<string, string | null> = {
+  setDate: 'setDate',
+  setFullYear: '{setYear,setMonth,setDate}',
+  setHours: '{setHours,setMinutes,setSeconds,setMilliseconds}',
+  setMilliseconds: 'setMilliseconds',
+  setMinutes: 'setMinutes',
+  setMonth: 'setMonth',
+  setSeconds: 'setSeconds',
+  setTime: 'fromUnixTime',
+  setUTCDate: null,
+  setUTCFullYear: null,
+  setUTCHours: null,
+  setUTCMilliseconds: null,
+  setUTCMinutes: null,
+  setUTCMonth: null,
+  setUTCSeconds: null,
+  setYear: 'setYear',
+}
+
+function formatSuggestion(
+  methodName: string,
+  suggestion: string | null
+): string {
+  if (suggestion === null) {
+    return ''
+  }
+  return ` Replace \`Date.${methodName}\` with \`date-fns/${suggestion}\``
+}
+
+function isDate(symbol: ts.Symbol, typeChecker: ts.TypeChecker): boolean {
+  return (
+    typeChecker.typeToString(
+      typeChecker.getTypeOfSymbolAtLocation(symbol, symbol.valueDeclaration)
+    ) === 'DateConstructor'
+  )
+}
+
+export default util.createRule<[], MessageIds>({
+  name: 'ban-date-mutation',
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'Bans mutating Date objects',
+      category: 'Best Practices',
+      recommended: 'error',
+    },
+    messages: {
+      banDateMutation: "Don't mutate a Date with `{{method}}`.{{suggestion}}",
+    },
+    schema: [],
+  },
+  defaultOptions: [],
+  create(context) {
+    return {
+      MemberExpression(node): void {
+        const parserServices = util.getParserServices(context)
+        const typeChecker = parserServices.program.getTypeChecker()
+        const objectType = typeChecker
+          .getTypeAtLocation(
+            parserServices.esTreeNodeToTSNodeMap.get(node.object)
+          )
+          .getSymbol()
+        if (objectType != null && isDate(objectType, typeChecker)) {
+          const dateMethod = typeChecker
+            .getTypeAtLocation(
+              parserServices.esTreeNodeToTSNodeMap.get(node.property)
+            )
+            .getSymbol()
+            ?.getEscapedName()
+          if (dateMethod == null) {
+            return
+          }
+          const dateMethodString = dateMethod.toString()
+          if (disallowedDateMethods.has(dateMethodString)) {
+            context.report({
+              node,
+              data: {
+                method: dateMethod,
+                suggestion: formatSuggestion(
+                  dateMethodString,
+                  methodToDateFns[dateMethodString]
+                ),
+              },
+              messageId: 'banDateMutation',
+            })
+          }
+        }
+      },
+    }
+  },
+})

src/rules/index.ts

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+import banDateMutation from './ban-date-mutation'
+
+export default {
+  'ban-date-mutation': banDateMutation,
+}

src/util.ts

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+import { ESLintUtils } from '@typescript-eslint/experimental-utils'
+
+const { getParserServices } = ESLintUtils
+
+const version = require('../package.json').version
+
+export const createRule = ESLintUtils.RuleCreator(
+  (name) =>
+    `https://github.com/chdsbd/eslint-plugin-better-dates/blob/v${version}/packages/eslint-plugin/docs/rules/${name}.md`
+)
+
+export { getParserServices }