feat: stricter validation of heading fragments by being Case sensitive

Fixes #8

BREAKING CHANGE: Heading fragments is now Case sensitive.
For example "#ExistIng-Heading" is invalid as it should be "#existing-heading".

.eslintrc.json

@@ -1,7 +1,11 @@
 {
   "extends": ["conventions", "prettier"],
-  "plugins": ["prettier"],
+  "plugins": ["prettier", "import", "unicorn"],
+  "parserOptions": {
+    "project": "./tsconfig.json"
+  },
   "rules": {
-    "prettier/prettier": "error"
+    "prettier/prettier": "error",
+    "import/extensions": ["error", "always"]
   }
 }

.github/ISSUE_TEMPLATE/BUG.md

@@ -1,8 +1,8 @@
 ---
-name: '🐛 Bug Report'
+name: "🐛 Bug Report"
-about: 'Report an unexpected problem or unintended behavior.'
+about: "Report an unexpected problem or unintended behavior."
-title: '[Bug]'
+title: "[Bug]"
-labels: 'bug'
+labels: "bug"
 ---
 
 <!--

.github/ISSUE_TEMPLATE/DOCUMENTATION.md

@@ -1,8 +1,8 @@
 ---
-name: '📜 Documentation'
+name: "📜 Documentation"
-about: 'Correct spelling errors, improvements or additions to documentation files (README, CONTRIBUTING...).'
+about: "Correct spelling errors, improvements or additions to documentation files (README, CONTRIBUTING...)."
-title: '[Documentation]'
+title: "[Documentation]"
-labels: 'documentation'
+labels: "documentation"
 ---
 
 <!-- Please make sure your issue has not already been fixed. -->

.github/ISSUE_TEMPLATE/FEATURE_REQUEST.md

@@ -1,8 +1,8 @@
 ---
-name: '✨ Feature Request'
+name: "✨ Feature Request"
-about: 'Suggest a new feature idea.'
+about: "Suggest a new feature idea."
-title: '[Feature]'
+title: "[Feature]"
-labels: 'feature request'
+labels: "feature request"
 ---
 
 <!-- Please make sure your issue has not already been fixed. -->

.github/ISSUE_TEMPLATE/IMPROVEMENT.md

@@ -1,8 +1,8 @@
 ---
-name: '🔧 Improvement'
+name: "🔧 Improvement"
-about: 'Improve structure/format/performance/refactor/tests of the code.'
+about: "Improve structure/format/performance/refactor/tests of the code."
-title: '[Improvement]'
+title: "[Improvement]"
-labels: 'improvement'
+labels: "improvement"
 ---
 
 <!-- Please make sure your issue has not already been fixed. -->

.github/ISSUE_TEMPLATE/QUESTION.md

@@ -1,8 +1,8 @@
 ---
-name: '🙋 Question'
+name: "🙋 Question"
-about: 'Further information is requested.'
+about: "Further information is requested."
-title: '[Question]'
+title: "[Question]"
-labels: 'question'
+labels: "question"
 ---
 
 ### Question

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,6 +1,6 @@
 <!-- Please first discuss the change you wish to make via issue before making a change. It might avoid a waste of your time. -->
 
-## What changes this PR introduce?
+# What changes this PR introduce?
 
 ## List any relevant issue numbers
 

.github/workflows/lint.yml

@@ -1,4 +1,4 @@
-name: 'Lint'
+name: "Lint"
 
 on:
   push:
@@ -8,21 +8,22 @@ on:
 
 jobs:
   lint:
-    runs-on: 'ubuntu-latest'
+    runs-on: "ubuntu-latest"
     steps:
-      - uses: 'actions/checkout@v3.0.0'
+      - uses: "actions/checkout@v4.1.1"
 
-      - name: 'Use Node.js'
+      - name: "Setup Node.js"
-        uses: 'actions/setup-node@v3.1.0'
+        uses: "actions/setup-node@v4.0.2"
         with:
-          node-version: 'lts/*'
+          node-version: "lts/*"
-          cache: 'npm'
+          cache: "npm"
 
-      - name: 'Install'
+      - name: "Install dependencies"
-        run: 'npm install'
+        run: "npm clean-install"
 
       - run: 'npm run lint:commit -- --to "${{ github.sha }}"'
-      - run: 'npm run lint:editorconfig'
+      - run: "npm run lint:editorconfig"
-      - run: 'npm run lint:markdown'
+      - run: "npm run lint:markdown"
-      - run: 'npm run lint:eslint'
+      - run: "npm run lint:eslint"
-      - run: 'npm run lint:prettier'
+      - run: "npm run lint:prettier"
+      - run: "npm run lint:javascript"

.github/workflows/release.yml

@@ -1,4 +1,4 @@
-name: 'Release'
+name: "Release"
 
 on:
   push:
@@ -6,24 +6,32 @@ on:
 
 jobs:
   release:
-    runs-on: 'ubuntu-latest'
+    runs-on: "ubuntu-latest"
+    permissions:
+      contents: "write"
+      issues: "write"
+      pull-requests: "write"
+      id-token: "write"
     steps:
-      - uses: 'actions/checkout@v3.0.0'
+      - uses: "actions/checkout@v4.1.1"
         with:
           fetch-depth: 0
           persist-credentials: false
 
-      - name: 'Use Node.js'
+      - name: "Setup Node.js"
-        uses: 'actions/setup-node@v3.1.0'
+        uses: "actions/setup-node@v4.0.2"
         with:
-          node-version: 'lts/*'
+          node-version: "lts/*"
-          cache: 'npm'
+          cache: "npm"
 
-      - name: 'Install'
+      - name: "Install dependencies"
-        run: 'npm install'
+        run: "npm clean-install"
 
-      - name: 'Release'
+      - name: "Verify the integrity of provenance attestations and registry signatures for installed dependencies"
-        run: 'npm run release'
+        run: "npm audit signatures"
+
+      - name: "Release"
+        run: "npm run release"
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           NPM_TOKEN: ${{ secrets.NPM_TOKEN }}

.github/workflows/test.yml

@@ -1,4 +1,4 @@
-name: 'Test'
+name: "Test"
 
 on:
   push:
@@ -8,18 +8,18 @@ on:
 
 jobs:
   test:
-    runs-on: 'ubuntu-latest'
+    runs-on: "ubuntu-latest"
     steps:
-      - uses: 'actions/checkout@v3.0.0'
+      - uses: "actions/checkout@v4.1.1"
 
-      - name: 'Use Node.js'
+      - name: "Setup Node.js"
-        uses: 'actions/setup-node@v3.1.0'
+        uses: "actions/setup-node@v4.0.2"
         with:
-          node-version: 'lts/*'
+          node-version: "lts/*"
-          cache: 'npm'
+          cache: "npm"
 
-      - name: 'Install'
+      - name: "Install dependencies"
-        run: 'npm install'
+        run: "npm clean-install"
 
-      - name: 'Test'
+      - name: "Test"
-        run: 'npm run test'
+        run: "npm run test"

.husky/commit-msg

@@ -1,4 +1,3 @@
-#!/bin/sh
+#!/usr/bin/env sh
-. "$(dirname "$0")/_/husky.sh"
 
 npm run lint:commit -- --edit

.husky/pre-commit

@@ -1,5 +1,5 @@
-#!/bin/sh
+#!/usr/bin/env sh
-. "$(dirname "$0")/_/husky.sh"
 
 npm run lint:staged
+npm run lint:javascript
 npm run test

.lintstagedrc.json

@@ -1,6 +1,7 @@
 {
-  "*": ["editorconfig-checker"],
+  "**/*": ["editorconfig-checker", "prettier --write --ignore-unknown"],
-  "*.{js,jsx,ts,tsx}": ["prettier --write", "eslint --fix"],
+  "**/*.md": ["markdownlint-cli2 --fix --no-globs"],
-  "*.{json,jsonc,yml,yaml}": ["prettier --write"],
+  "**/*.{js,jsx,ts,tsx}": [
-  "*.{md,mdx}": ["prettier --write", "markdownlint-cli2 --fix"]
+    "eslint --fix --max-warnings 0 --report-unused-disable-directives"
+  ]
 }

.markdownlint-cli2.jsonc

@@ -1,5 +1,11 @@
 {
-  "globs": ["**/*.{md,mdx}"],
+  "config": {
-  "ignores": ["**/node_modules", "**/test/fixtures"],
+    "extends": "markdownlint/style/prettier",
-  "customRules": ["./src/index.js"]
+    "default": true,
+    "relative-links": true,
+    "no-inline-html": false,
+  },
+  "globs": ["**/*.md"],
+  "ignores": ["**/node_modules", "**/test/fixtures/**"],
+  "customRules": ["./src/index.js"],
 }

.markdownlint.json

@@ -1,8 +0,0 @@
-{
-  "default": true,
-  "relative-links": true,
-  "extends": "markdownlint/style/prettier",
-  "MD024": false,
-  "MD033": false,
-  "MD041": false
-}

.npmrc

@@ -1 +1,2 @@
 save-exact=true
+provenance=true

.prettierrc.json

@@ -1,6 +1,3 @@
 {
-  "singleQuote": true,
+  "semi": false
-  "jsxSingleQuote": true,
-  "semi": false,
-  "trailingComma": "none"
 }

.taprc

@@ -1,8 +0,0 @@
-ts: false
-jsx: false
-flow: false
-check-coverage: false
-coverage: false
-
-files:
-  - 'test/**/*.test.js'

.vscode/settings.json

@@ -3,6 +3,6 @@
   "prettier.configPath": ".prettierrc.json",
   "editor.formatOnSave": true,
   "editor.codeActionsOnSave": {
-    "source.fixAll": true
+    "source.fixAll": "explicit"
   }
 }

CODE_OF_CONDUCT.md

@@ -60,7 +60,7 @@ representative at an online or offline event.
 
 Instances of abusive, harassing, or otherwise unacceptable behavior may be
 reported to the community leaders responsible for enforcement at
-contact@divlo.fr.
+<contact@theoludwig.fr>.
 All complaints will be reviewed and investigated promptly and fairly.
 
 All community leaders are obligated to respect the privacy and security of the

CONTRIBUTING.md

@@ -2,6 +2,14 @@
 
 Thanks a lot for your interest in contributing to **markdownlint-rule-relative-links**! 🎉
 
+## Code of Conduct
+
+**markdownlint-rule-relative-links** adopted the [Contributor Covenant](https://www.contributor-covenant.org/) as its Code of Conduct, and we expect project participants to adhere to it. Please read [the full text](./CODE_OF_CONDUCT.md) so that you can understand what actions will and will not be tolerated.
+
+## Open Development
+
+All work on **markdownlint-rule-relative-links** happens directly on this repository. Both core team members and external contributors send pull requests which go through the same review process.
+
 ## Types of contributions
 
 - Reporting a bug.
@@ -11,7 +19,7 @@ Thanks a lot for your interest in contributing to **markdownlint-rule-relative-l
 
 ## Pull Requests
 
-- **Please first discuss** the change you wish to make via [issue](https://github.com/Divlo/markdownlint-rule-relative-links/issues) before making a change. It might avoid a waste of your time.
+- **Please first discuss** the change you wish to make via [issue](https://github.com/theoludwig/markdownlint-rule-relative-links/issues) before making a change. It might avoid a waste of your time.
 
 - Ensure your code respect linting.
 
@@ -21,26 +29,4 @@ If you're adding new features to **markdownlint-rule-relative-links**, please in
 
 ## Commits
 
-The commit message guidelines respect [@commitlint/config-conventional](https://github.com/conventional-changelog/commitlint/tree/master/%40commitlint/config-conventional) and [Semantic Versioning](https://semver.org/) for releases.
+The commit message guidelines adheres to [Conventional Commits](https://www.conventionalcommits.org/) and [Semantic Versioning](https://semver.org/) for releases.
-
-### Types
-
-Types define which kind of changes you made to the project.
-
-| Types    | Description                                                                                                  |
-| -------- | ------------------------------------------------------------------------------------------------------------ |
-| feat     | A new feature.                                                                                               |
-| fix      | A bug fix.                                                                                                   |
-| docs     | Documentation only changes.                                                                                  |
-| style    | Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc).      |
-| refactor | A code change that neither fixes a bug nor adds a feature.                                                   |
-| perf     | A code change that improves performance.                                                                     |
-| test     | Adding missing tests or correcting existing tests.                                                           |
-| build    | Changes that affect the build system or external dependencies (example scopes: gulp, broccoli, npm).         |
-| ci       | Changes to our CI configuration files and scripts (example scopes: Travis, Circle, BrowserStack, SauceLabs). |
-| chore    | Other changes that don't modify src or test files.                                                           |
-| revert   | Reverts a previous commit.                                                                                   |
-
-### Scopes
-
-Scopes define what part of the code changed.

LICENSE

@@ -1,6 +1,6 @@
-MIT License
+# MIT License
 
-Copyright (c) Divlo
+Copyright (c) Théo LUDWIG <contact@theoludwig.fr>
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -4,15 +4,13 @@
   <strong>Custom rule for <a href="https://github.com/DavidAnson/markdownlint">markdownlint</a> to validate relative links.</strong>
 </p>
 
-</p>
-
 <p align="center">
-  <a href="./CONTRIBUTING.md"><img src="https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat" /></a>
+  <a href="./CONTRIBUTING.md"><img src="https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat" alt="CONTRIBUTING" /></a>
   <a href="./LICENSE"><img src="https://img.shields.io/badge/licence-MIT-blue.svg" alt="Licence MIT"/></a>
   <a href="./CODE_OF_CONDUCT.md"><img src="https://img.shields.io/badge/Contributor%20Covenant-v2.0%20adopted-ff69b4.svg" alt="Contributor Covenant" /></a>
   <br />
-  <a href="https://github.com/Divlo/markdownlint-rule-relative-links/actions/workflows/lint.yml"><img src="https://github.com/Divlo/markdownlint-rule-relative-links/actions/workflows/lint.yml/badge.svg?branch=develop" /></a>
+  <a href="https://github.com/theoludwig/markdownlint-rule-relative-links/actions/workflows/lint.yml"><img src="https://github.com/theoludwig/markdownlint-rule-relative-links/actions/workflows/lint.yml/badge.svg?branch=develop" alt="Lint" /></a>
-  <a href="https://github.com/Divlo/emarkdownlint-rule-relative-linksactions/workflows/test.yml"><img src="https://github.com/Divlo/markdownlint-rule-relative-links/actions/workflows/test.yml/badge.svg?branch=develop" /></a>
+  <a href="https://github.com/theoludwig/markdownlint-rule-relative-links/actions/workflows/test.yml"><img src="https://github.com/theoludwig/markdownlint-rule-relative-links/actions/workflows/test.yml/badge.svg?branch=develop" alt="Test" /></a>
   <br />
   <a href="https://conventionalcommits.org"><img src="https://img.shields.io/badge/Conventional%20Commits-1.0.0-yellow.svg" alt="Conventional Commits" /></a>
   <a href="https://github.com/semantic-release/semantic-release"><img src="https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg" alt="semantic-release" /></a>
@@ -23,9 +21,44 @@
 
 **markdownlint-rule-relative-links** is a [markdownlint](https://github.com/DavidAnson/markdownlint) custom rule to validate relative links.
 
-It ensures that relative links that start with `./` or `../` (or not starting with external protocols like `http://` or `https://`) are working and not "dead" which means that it exists in the file system of the project that uses `markdownlint`.
+It ensures that relative links (using `file:` protocol) are working and exists in the file system of the project that uses [markdownlint](https://github.com/DavidAnson/markdownlint).
 
-Related links:
+### Example
+
+File structure:
+
+```txt
+├── abc.txt
+└── awesome.md
+```
+
+With `awesome.md` content:
+
+```md
+[abc](./abc.txt)
+
+[Invalid link](./invalid.txt)
+```
+
+Running [markdownlint-cli2](https://github.com/DavidAnson/markdownlint-cli2) with `markdownlint-rule-relative-links` will output:
+
+```sh
+awesome.md:3 relative-links Relative links should be valid ["./invalid.txt" should exist in the file system]
+```
+
+### Additional features
+
+- Support images (e.g: `![Image](./image.png)`).
+- Support links fragments similar to the [built-in `markdownlint` rule - MD051](https://github.com/DavidAnson/markdownlint/blob/main/doc/md051.md) (e.g: `[Link](./awesome.md#heading)`).
+- Ignore external links and absolute paths as it only checks relative links (e.g: `https://example.com/` or `/absolute/path.png`).
+
+### Limitations
+
+- Only images and links defined using markdown syntax are validated, html syntax is ignored (e.g: `<a href="./link.txt" />` or `<img src="./image.png" />`).
+
+Contributions are welcome to improve the rule, and to alleviate these limitations. See [CONTRIBUTING.md](./CONTRIBUTING.md) for more information.
+
+### Related links
 
 - [DavidAnson/markdownlint#253](https://github.com/DavidAnson/markdownlint/issues/253)
 - [DavidAnson/markdownlint#121](https://github.com/DavidAnson/markdownlint/issues/121)
@@ -33,7 +66,7 @@ Related links:
 
 ## Prerequisites
 
-- [Node.js](https://nodejs.org/) >= 16.0.0
+[Node.js](https://nodejs.org/) >= 16.0.0
 
 ## Installation
 
@@ -43,9 +76,9 @@ npm install --save-dev markdownlint-rule-relative-links
 
 ## Configuration
 
-There are various ways `markdownlint` can be configured using objects, config files etc. For more information on `markdownlint` configuration refer [options.config](https://github.com/DavidAnson/markdownlint#optionsconfig).
+There are various ways [markdownlint](https://github.com/DavidAnson/markdownlint) can be configured using objects, config files etc. For more information on configuration refer to [options.config](https://github.com/DavidAnson/markdownlint#optionsconfig).
 
-We recommend configuring `markdownlint-cli2` over `markdownlint-cli` for compatibility with the `vscode-markdownlint` plugin.
+We recommend configuring [markdownlint-cli2](https://github.com/DavidAnson/markdownlint-cli2) over [markdownlint-cli](https://github.com/igorshubovych/markdownlint-cli) for compatibility with the [vscode-markdownlint](https://github.com/DavidAnson/vscode-markdownlint) extension.
 
 `.markdownlint-cli2.jsonc`
 
@@ -55,7 +88,7 @@ We recommend configuring `markdownlint-cli2` over `markdownlint-cli` for compati
     "default": true,
     "relative-links": true
   },
-  "globs": ["**/*.{md,mdx}"],
+  "globs": ["**/*.md"],
   "ignores": ["**/node_modules"],
   "customRules": ["markdownlint-rule-relative-links"]
 }

jsconfig.json

@@ -0,0 +1,25 @@
+{
+  "compilerOptions": {
+    "lib": ["ESNext"],
+    "target": "ESNext",
+    "module": "CommonJS",
+    "moduleResolution": "Node",
+    "checkJs": true,
+    "allowJs": true,
+    "noEmit": true,
+    "rootDir": ".",
+    "baseUrl": ".",
+    "skipLibCheck": true,
+    "strict": true,
+    "allowUnusedLabels": false,
+    "allowUnreachableCode": false,
+    "noFallthroughCasesInSwitch": true,
+    "noImplicitAny": true,
+    "noImplicitOverride": true,
+    "noImplicitReturns": true,
+    "noUncheckedIndexedAccess": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "forceConsistentCasingInFileNames": true
+  }
+}

package.json

@@ -3,16 +3,16 @@
   "version": "0.0.0-development",
   "public": true,
   "description": "Custom rule for markdownlint to validate relative links.",
-  "author": "Divlo <contact@divlo.fr>",
+  "author": "Théo LUDWIG <contact@theoludwig.fr>",
   "license": "MIT",
   "repository": {
     "type": "git",
-    "url": "https://github.com/Divlo/markdownlint-rule-relative-links.git"
+    "url": "https://github.com/theoludwig/markdownlint-rule-relative-links.git"
   },
   "bugs": {
-    "url": "https://github.com/Divlo/markdownlint-rule-relative-links/issues"
+    "url": "https://github.com/theoludwig/markdownlint-rule-relative-links/issues"
   },
-  "homepage": "https://github.com/Divlo/markdownlint-rule-relative-links#readme",
+  "homepage": "https://github.com/theoludwig/markdownlint-rule-relative-links#readme",
   "keywords": [
     "markdownlint",
     "markdownlint-rule"
@@ -21,42 +21,51 @@
   "files": [
     "src"
   ],
+  "publishConfig": {
+    "access": "public",
+    "provenance": true
+  },
   "engines": {
     "node": ">=16.0.0",
-    "npm": ">=8.0.0"
+    "npm": ">=9.0.0"
   },
   "scripts": {
     "lint:commit": "commitlint",
     "lint:editorconfig": "editorconfig-checker",
     "lint:markdown": "markdownlint-cli2",
-    "lint:eslint": "eslint \"**/*.{js,jsx,ts,tsx}\" --ignore-path \".gitignore\"",
+    "lint:eslint": "eslint . --max-warnings 0 --report-unused-disable-directives --ignore-path .gitignore",
-    "lint:prettier": "prettier \".\" --check --ignore-path \".gitignore\"",
+    "lint:prettier": "prettier . --check --ignore-path .gitignore",
+    "lint:javascript": "tsc --project jsconfig.json --noEmit",
     "lint:staged": "lint-staged",
-    "test": "tap",
+    "test": "node --test",
     "release": "semantic-release",
-    "postinstall": "husky install",
+    "postinstall": "husky",
     "prepublishOnly": "pinst --disable",
     "postpublish": "pinst --enable"
   },
+  "dependencies": {
+    "markdown-it": "14.1.0"
+  },
   "devDependencies": {
-    "@commitlint/cli": "17.3.0",
+    "@commitlint/cli": "19.2.2",
-    "@commitlint/config-conventional": "17.3.0",
+    "@commitlint/config-conventional": "19.2.2",
-    "@types/tap": "15.0.7",
+    "@types/markdown-it": "14.1.1",
-    "editorconfig-checker": "4.0.2",
+    "@types/node": "20.12.12",
-    "eslint": "8.31.0",
+    "editorconfig-checker": "5.1.5",
-    "eslint-config-conventions": "6.0.0",
+    "eslint": "8.57.0",
-    "eslint-config-prettier": "8.5.0",
+    "eslint-config-conventions": "14.2.0",
-    "eslint-plugin-import": "2.26.0",
+    "eslint-config-prettier": "9.1.0",
-    "eslint-plugin-prettier": "4.2.1",
+    "eslint-plugin-import": "2.29.1",
-    "eslint-plugin-promise": "6.1.1",
+    "eslint-plugin-prettier": "5.1.3",
-    "eslint-plugin-unicorn": "45.0.2",
+    "eslint-plugin-promise": "6.2.0",
-    "husky": "8.0.2",
+    "eslint-plugin-unicorn": "53.0.0",
-    "lint-staged": "13.1.0",
+    "husky": "9.0.11",
-    "markdownlint": "0.27.0",
+    "lint-staged": "15.2.5",
-    "markdownlint-cli2": "0.6.0",
+    "markdownlint": "0.34.0",
+    "markdownlint-cli2": "0.13.0",
     "pinst": "3.0.0",
-    "prettier": "2.8.1",
+    "prettier": "3.2.5",
-    "semantic-release": "19.0.5",
+    "semantic-release": "23.1.1",
-    "tap": "16.3.2"
+    "typescript": "5.4.5"
   }
 }

src/index.js

@@ -1,96 +1,175 @@
-'use strict'
+"use strict"
 
-const { pathToFileURL } = require('node:url')
+const { pathToFileURL } = require("node:url")
-const fs = require('node:fs')
+const fs = require("node:fs")
+
+const { filterTokens } = require("./markdownlint-rule-helpers/helpers.js")
+const {
+  convertHeadingToHTMLFragment,
+  getMarkdownHeadings,
+  getMarkdownIdOrAnchorNameFragments,
+  isValidIntegerString,
+  getNumberOfLines,
+  getLineNumberStringFromFragment,
+  lineFragmentRe,
+} = require("./utils.js")
+
+/** @typedef {import('markdownlint').Rule} MarkdownLintRule */
 
 /**
- * Calls the provided function for each matching token.
+ * @type {MarkdownLintRule}
- *
- * @param {Object} params RuleParams instance.
- * @param {string} type Token type identifier.
- * @param {Function} handler Callback function.
- * @returns {void}
  */
-const filterTokens = (params, type, handler) => {
+const customRule = {
-  for (const token of params.tokens) {
+  names: ["relative-links"],
-    if (token.type === type) {
+  description: "Relative links should be valid",
-      handler(token)
+  tags: ["links"],
+  parser: "markdownit",
+  function: (params, onError) => {
+    filterTokens(params, "inline", (token) => {
+      const children = token.children ?? []
+      for (const child of children) {
+        const { type, attrs, lineNumber } = child
+
+        /** @type {string | undefined} */
+        let hrefSrc
+
+        if (type === "link_open") {
+          for (const attr of attrs) {
+            if (attr[0] === "href") {
+              hrefSrc = attr[1]
+              break
             }
           }
         }
 
-/**
+        if (type === "image") {
- * Adds a generic error object via the onError callback.
+          for (const attr of attrs) {
- *
+            if (attr[0] === "src") {
- * @param {Object} onError RuleOnError instance.
+              hrefSrc = attr[1]
- * @param {number} lineNumber Line number.
+              break
- * @param {string} [detail] Error details.
+            }
- * @param {string} [context] Error context.
+          }
- * @param {number[]} [range] Column and length of error.
+        }
- * @param {Object} [fixInfo] RuleOnErrorFixInfo instance.
+
- * @returns {void}
+        if (hrefSrc == null) {
- */
+          continue
-const addError = (onError, lineNumber, detail, context, range, fixInfo) => {
+        }
+
+        const url = new URL(hrefSrc, pathToFileURL(params.name))
+        const isRelative =
+          url.protocol === "file:" &&
+          !hrefSrc.startsWith("/") &&
+          !hrefSrc.startsWith("#")
+
+        if (!isRelative) {
+          continue
+        }
+
+        const detail = `"${hrefSrc}"`
+
+        if (!fs.existsSync(url)) {
           onError({
             lineNumber,
-    detail,
+            detail: `${detail} should exist in the file system`,
-    context,
-    range,
-    fixInfo
           })
+          continue
         }
 
-const EXTERNAL_PROTOCOLS = new Set([
+        if (url.hash.length <= 0) {
-  'http:',
+          if (hrefSrc.includes("#")) {
-  'https:',
+            if (type === "image") {
-  'mailto:',
+              onError({
-  'tel:',
+                lineNumber,
-  'ftp:'
+                detail: `${detail} should not have a fragment identifier as it is an image`,
-])
-
-const customRule = {
-  names: ['relative-links'],
-  description: 'Relative links should be valid',
-  tags: ['links'],
-  function: (params, onError) => {
-    filterTokens(params, 'inline', (token) => {
-      token.children.forEach((child) => {
-        const { lineNumber, type, attrs } = child
-
-        /** @type {string | null} */
-        let hrefSrc = null
-
-        if (type === 'link_open') {
-          attrs.forEach((attr) => {
-            if (attr[0] === 'href') {
-              hrefSrc = attr[1]
-            }
               })
+              continue
             }
 
-        if (type === 'image') {
+            onError({
-          attrs.forEach((attr) => {
+              lineNumber,
-            if (attr[0] === 'src') {
+              detail: `${detail} should have a valid fragment identifier`,
-              hrefSrc = attr[1]
-            }
             })
+            continue
+          }
+          continue
         }
 
-        if (hrefSrc != null) {
+        if (type === "image") {
-          const url = new URL(hrefSrc, pathToFileURL(params.name))
+          onError({
-          url.hash = ''
+            lineNumber,
-          const isRelative =
+            detail: `${detail} should not have a fragment identifier as it is an image`,
-            hrefSrc.startsWith('./') ||
+          })
-            hrefSrc.startsWith('../') ||
+          continue
-            !EXTERNAL_PROTOCOLS.has(url.protocol)
+        }
-          if (isRelative && !fs.existsSync(url.pathname)) {
+
-            const detail = `Link "${hrefSrc}" is dead`
+        if (!url.pathname.endsWith(".md")) {
-            addError(onError, lineNumber, detail)
+          continue
+        }
+
+        const fileContent = fs.readFileSync(url, { encoding: "utf8" })
+        const headings = getMarkdownHeadings(fileContent)
+        const idOrAnchorNameHTMLFragments =
+          getMarkdownIdOrAnchorNameFragments(fileContent)
+
+        /** @type {Map<string, number>} */
+        const fragments = new Map()
+
+        const fragmentsHTML = headings.map((heading) => {
+          const fragment = convertHeadingToHTMLFragment(heading)
+          const count = fragments.get(fragment) ?? 0
+          fragments.set(fragment, count + 1)
+          if (count !== 0) {
+            return `${fragment}-${count}`
+          }
+          return fragment
+        })
+
+        fragmentsHTML.push(...idOrAnchorNameHTMLFragments)
+
+        if (!fragmentsHTML.includes(url.hash)) {
+          if (url.hash.startsWith("#L")) {
+            const lineNumberFragmentString = getLineNumberStringFromFragment(
+              url.hash,
+            )
+
+            const hasOnlyDigits = isValidIntegerString(lineNumberFragmentString)
+            if (!hasOnlyDigits) {
+              if (lineFragmentRe.test(url.hash)) {
+                continue
+              }
+
+              onError({
+                lineNumber,
+                detail: `${detail} should have a valid fragment identifier`,
+              })
+              continue
+            }
+
+            const lineNumberFragment = Number.parseInt(
+              lineNumberFragmentString,
+              10,
+            )
+            const numberOfLines = getNumberOfLines(fileContent)
+            if (lineNumberFragment > numberOfLines) {
+              onError({
+                lineNumber,
+                detail: `${detail} should have a valid fragment identifier, ${detail} should have at least ${lineNumberFragment} lines to be valid`,
+              })
+              continue
+            }
+
+            continue
+          }
+
+          onError({
+            lineNumber,
+            detail: `${detail} should have a valid fragment identifier`,
+          })
+          continue
         }
       }
     })
-    })
+  },
-  }
 }
 
 module.exports = customRule

src/markdownlint-rule-helpers/helpers.js

@@ -0,0 +1,38 @@
+/**
+ * Dependency Vendoring of `markdownlint-rule-helpers`
+ * @see https://www.npmjs.com/package/markdownlint-rule-helpers
+ */
+
+/** @typedef {import('markdownlint').RuleParams} MarkdownLintRuleParams */
+/** @typedef {import('markdownlint').MarkdownItToken} MarkdownItToken */
+
+/**
+ * Calls the provided function for each matching token.
+ *
+ * @param {MarkdownLintRuleParams} params RuleParams instance.
+ * @param {string} type Token type identifier.
+ * @param {(token: MarkdownItToken) => void} handler Callback function.
+ * @returns {void}
+ */
+const filterTokens = (params, type, handler) => {
+  for (const token of params.parsers.markdownit.tokens) {
+    if (token.type === type) {
+      handler(token)
+    }
+  }
+}
+
+/**
+ * Gets a Regular Expression for matching the specified HTML attribute.
+ *
+ * @param {string} name HTML attribute name.
+ * @returns {RegExp} Regular Expression for matching.
+ */
+const getHtmlAttributeRe = (name) => {
+  return new RegExp(`\\s${name}\\s*=\\s*['"]?([^'"\\s>]*)`, "iu")
+}
+
+module.exports = {
+  filterTokens,
+  getHtmlAttributeRe,
+}

src/utils.js

@@ -0,0 +1,163 @@
+const MarkdownIt = require("markdown-it")
+
+const { getHtmlAttributeRe } = require("./markdownlint-rule-helpers/helpers.js")
+
+const markdownIt = new MarkdownIt({ html: true })
+
+const lineFragmentRe = /^#(?:L\d+(?:C\d+)?-L\d+(?:C\d+)?|L\d+)$/
+
+/**
+ * Converts a Markdown heading into an HTML fragment according to the rules
+ * used by GitHub.
+ *
+ * @see https://github.com/DavidAnson/markdownlint/blob/d01180ec5a014083ee9d574b693a8d7fbc1e566d/lib/md051.js#L1
+ * @param {string} inlineText Inline token for heading.
+ * @returns {string} Fragment string for heading.
+ */
+const convertHeadingToHTMLFragment = (inlineText) => {
+  return (
+    "#" +
+    encodeURIComponent(
+      inlineText
+        .toLowerCase()
+        // RegExp source with Ruby's \p{Word} expanded into its General Categories
+        // https://github.com/gjtorikian/html-pipeline/blob/main/lib/html/pipeline/toc_filter.rb
+        // https://ruby-doc.org/core-3.0.2/Regexp.html
+        .replace(
+          /[^\p{Letter}\p{Mark}\p{Number}\p{Connector_Punctuation}\- ]/gu,
+          "",
+        )
+        .replace(/ /gu, "-"),
+    )
+  )
+}
+
+const headingTags = new Set(["h1", "h2", "h3", "h4", "h5", "h6"])
+const ignoredTokens = new Set(["heading_open", "heading_close"])
+
+/**
+ * Gets the headings from a Markdown string.
+ * @param {string} content
+ * @returns {string[]}
+ */
+const getMarkdownHeadings = (content) => {
+  const tokens = markdownIt.parse(content, {})
+
+  /** @type {string[]} */
+  const headings = []
+
+  /** @type {string | null} */
+  let headingToken = null
+
+  for (const token of tokens) {
+    if (headingTags.has(token.tag)) {
+      if (token.type === "heading_open") {
+        headingToken = token.markup
+      } else if (token.type === "heading_close") {
+        headingToken = null
+      }
+    }
+
+    if (ignoredTokens.has(token.type)) {
+      continue
+    }
+
+    if (headingToken === null) {
+      continue
+    }
+
+    const children = token.children ?? []
+
+    headings.push(
+      `${children
+        .map((token) => {
+          return token.content
+        })
+        .join("")}`,
+    )
+  }
+
+  return headings
+}
+
+const nameHTMLAttributeRegex = getHtmlAttributeRe("name")
+const idHTMLAttributeRegex = getHtmlAttributeRe("id")
+
+/**
+ * Gets the id or anchor name fragments from a Markdown string.
+ * @param {string} content
+ * @returns {string[]}
+ */
+const getMarkdownIdOrAnchorNameFragments = (content) => {
+  const tokens = markdownIt.parse(content, {})
+
+  /** @type {string[]} */
+  const result = []
+
+  for (const token of tokens) {
+    const regexMatch =
+      idHTMLAttributeRegex.exec(token.content) ||
+      nameHTMLAttributeRegex.exec(token.content)
+    if (regexMatch == null) {
+      continue
+    }
+
+    const idOrName = regexMatch[1]
+    if (idOrName == null || idOrName.length <= 0) {
+      continue
+    }
+
+    const htmlFragment = "#" + idOrName
+    if (!result.includes(htmlFragment)) {
+      result.push(htmlFragment)
+    }
+  }
+
+  return result
+}
+
+/**
+ * Checks if a string is a valid integer.
+ *
+ * Using `Number.parseInt` combined with `Number.isNaN` will not be sufficient enough because `Number.parseInt("1abc", 10)` will return `1` (a valid number) instead of `NaN`.
+ *
+ * @param {string} value
+ * @returns {boolean}
+ * @example isValidIntegerString("1") // true
+ * @example isValidIntegerString("45") // true
+ * @example isValidIntegerString("1abc") // false
+ * @example isValidIntegerString("1.0") // false
+ */
+const isValidIntegerString = (value) => {
+  const regex = /^\d+$/
+  return regex.test(value)
+}
+
+/**
+ * Gets the number of lines in a string, based on the number of `\n` characters.
+ * @param {string} content
+ * @returns {number}
+ */
+const getNumberOfLines = (content) => {
+  return content.split("\n").length
+}
+
+/**
+ * Gets the line number string from a fragment.
+ * @param {string} fragment
+ * @returns {string}
+ * @example getLineNumberStringFromFragment("#L50") // 50
+ */
+const getLineNumberStringFromFragment = (fragment) => {
+  return fragment.slice(2)
+}
+
+module.exports = {
+  lineFragmentRe,
+  convertHeadingToHTMLFragment,
+  getMarkdownHeadings,
+  getMarkdownIdOrAnchorNameFragments,
+  isValidIntegerString,
+  getNumberOfLines,
+  getLineNumberStringFromFragment,
+}

test/basic.test.js

@@ -1,34 +0,0 @@
-const tap = require('tap')
-const { markdownlint } = require('markdownlint').promises
-
-const relativeLinks = require('../src/index.js')
-
-tap.test('ensure we validate correctly', async (t) => {
-  const lintResults = await markdownlint({
-    files: ['test/fixtures/Valid.md', 'test/fixtures/Invalid.md'],
-    config: {
-      'relative-links': true
-    },
-    customRules: [relativeLinks]
-  })
-  t.equal(lintResults['test/fixtures/Valid.md'].length, 0)
-  t.equal(lintResults['test/fixtures/Invalid.md'].length, 2)
-
-  t.equal(
-    lintResults['test/fixtures/Invalid.md'][0]?.ruleDescription,
-    'Relative links should be valid'
-  )
-  t.equal(
-    lintResults['test/fixtures/Invalid.md'][0]?.errorDetail,
-    'Link "./basic.test.js" is dead'
-  )
-
-  t.equal(
-    lintResults['test/fixtures/Invalid.md'][1]?.ruleDescription,
-    'Relative links should be valid'
-  )
-  t.equal(
-    lintResults['test/fixtures/Invalid.md'][1]?.errorDetail,
-    'Link "../image.png" is dead'
-  )
-})

test/fixtures/Invalid.md

@@ -1,5 +0,0 @@
-# Invalid
-
-[basic.js](./basic.test.js)
-
-![Image](../image.png)

test/fixtures/Valid.md

@@ -1,5 +0,0 @@
-# Valid
-
-[basic.js](../basic.test.js)
-
-![Image](./image.png)

test/fixtures/invalid/empty-id-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<div id>Content</div>

test/fixtures/invalid/empty-id-fragment/empty-id-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment](./awesome.md#)

test/fixtures/invalid/ignore-empty-fragment-checking-for-image.md

@@ -0,0 +1,3 @@
+# Invalid
+
+![Image](../image.png#)

test/fixtures/invalid/ignore-fragment-checking-for-image.md

@@ -0,0 +1,3 @@
+# Invalid
+
+![Image](../image.png#non-existing-fragment)

test/fixtures/invalid/ignore-name-fragment-if-not-an-anchor/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<input name="name-should-be-ignored" id="id-after-name" />

test/fixtures/invalid/ignore-name-fragment-if-not-an-anchor/ignore-name-fragment-if-not-an-anchor.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Invalid](./awesome.md#name-should-be-ignored)

test/fixtures/invalid/ignore-not-an-id-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<div data-id="not-an-id-should-be-ignored">Content</div>

test/fixtures/invalid/ignore-not-an-id-fragment/ignore-not-an-id-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Invalid](./awesome.md#not-an-id-should-be-ignored)

test/fixtures/invalid/invalid-heading-case-sensitive/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+## Existing Heading

test/fixtures/invalid/invalid-heading-case-sensitive/invalid-heading-case-sensitive.md

@@ -0,0 +1,3 @@
+# Valid
+
+[Link fragment](./awesome.md#ExistIng-Heading)

test/fixtures/invalid/invalid-heading-with-L-fragment/awesome.md

@@ -0,0 +1 @@
+# Awesome

test/fixtures/invalid/invalid-heading-with-L-fragment/invalid-heading-with-L-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment line number 7](./awesome.md#L7abc)

test/fixtures/invalid/invalid-line-column-range-number-fragment/awesome.md

@@ -0,0 +1 @@
+# Awesome

test/fixtures/invalid/invalid-line-column-range-number-fragment/invalid-line-column-range-number-fragment.md

@@ -0,0 +1,31 @@
+# Invalid
+
+[Invalid](./awesome.md#L12-not-a-line-link)
+
+[Invalid](./awesome.md#l7)
+
+[Invalid](./awesome.md#L)
+
+[Invalid](./awesome.md#L7extra)
+
+[Invalid](./awesome.md#L30C)
+
+[Invalid](./awesome.md#L30Cextra)
+
+[Invalid](./awesome.md#L30L12)
+
+[Invalid](./awesome.md#L30C12)
+
+[Invalid](./awesome.md#L30C11-)
+
+[Invalid](./awesome.md#L30C11-L)
+
+[Invalid](./awesome.md#L30C11-L31C)
+
+[Invalid](./awesome.md#L30C11-C31)
+
+[Invalid](./awesome.md#C30)
+
+[Invalid](./awesome.md#C11-C31)
+
+[Invalid](./awesome.md#C11-L4C31)

test/fixtures/invalid/invalid-line-number-fragment/awesome.md

@@ -0,0 +1 @@
+# Awesome

test/fixtures/invalid/invalid-line-number-fragment/invalid-line-number-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment line number 7](./awesome.md#L7)

test/fixtures/invalid/non-existing-anchor-name-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<a name="existing-heading-anchor">Link</a>

test/fixtures/invalid/non-existing-anchor-name-fragment/non-existing-anchor-name-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment](./awesome.md#non-existing-anchor-name-fragment)

test/fixtures/invalid/non-existing-element-id-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<div id="existing-element-id-fragment">Content</div>

test/fixtures/invalid/non-existing-element-id-fragment/non-existing-element-id-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment](./awesome.md#non-existing-element-id-fragment)

test/fixtures/invalid/non-existing-file.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[File](./index.test.js)

test/fixtures/invalid/non-existing-heading-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+## Existing Heading

test/fixtures/invalid/non-existing-heading-fragment/non-existing-heading-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment](./awesome.md#non-existing-heading)

test/fixtures/invalid/non-existing-image.md

@@ -0,0 +1,3 @@
+# Invalid
+
+![Image](./image.png)

test/fixtures/valid/existing-anchor-name-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<a name="existing-heading-anchor">Link</a>

test/fixtures/valid/existing-anchor-name-fragment/existing-anchor-name-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment](./awesome.md#existing-heading-anchor)

test/fixtures/valid/existing-element-id-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+<div id="existing-element-id-fragment">Content</div>

test/fixtures/valid/existing-element-id-fragment/existing-element-id-fragment.md

@@ -0,0 +1,3 @@
+# Invalid
+
+[Link fragment](./awesome.md#existing-element-id-fragment)

test/fixtures/valid/existing-file.md

@@ -0,0 +1,3 @@
+# Valid
+
+[File](../../index.test.js)

test/fixtures/valid/existing-heading-fragment/awesome.md

@@ -0,0 +1,13 @@
+# Awesome
+
+## Existing Heading
+
+### Repeated Heading
+
+Text
+
+### Repeated Heading
+
+Text
+
+### Repeated Heading

test/fixtures/valid/existing-heading-fragment/existing-heading-fragment.md

@@ -0,0 +1,9 @@
+# Valid
+
+[Link fragment](./awesome.md#existing-heading)
+
+[Link fragment Repeated 0](./awesome.md#repeated-heading)
+
+[Link fragment Repeated 1](./awesome.md#repeated-heading-1)
+
+[Link fragment Repeated 2](./awesome.md#repeated-heading-2)

test/fixtures/valid/existing-heading-with-accents/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+## Développement

test/fixtures/valid/existing-heading-with-accents/existing-heading-with-accents.md

@@ -0,0 +1,3 @@
+# Valid
+
+[Link fragment](./awesome.md#développement)

test/fixtures/valid/existing-image.md

@@ -0,0 +1,3 @@
+# Valid
+
+![Image](../image.png)

test/fixtures/valid/ignore-absolute-paths.md

@@ -0,0 +1,3 @@
+# Valid
+
+![Absolute Path](/absolute/path.png)

test/fixtures/valid/ignore-external-links.md

@@ -0,0 +1,7 @@
+# Valid
+
+[External https link](https://example.com/)
+
+[External https link 2](https:./external.https)
+
+[External ftp link](ftp:./external.ftp)

test/fixtures/valid/ignore-fragment-checking-in-own-file.md

@@ -0,0 +1,5 @@
+# Valid
+
+<div id="existing-element-id-fragment">Content</div>
+
+[Link fragment](#non-existing-element-id-fragment)

test/fixtures/valid/only-parse-markdown-files-for-fragments/awesome.html

@@ -0,0 +1,9 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Awesome</title>
+  </head>
+  <body></body>
+</html>

test/fixtures/valid/only-parse-markdown-files-for-fragments/only-parse-markdown-files-for-fragments.md

@@ -0,0 +1,7 @@
+# Valid
+
+[Link fragment HTML](./awesome.html#existing-heading)
+
+[Link fragment TXT](./abc.txt#existing-heading)
+
+[Link fragment Image](../../image.png#existing-heading)

test/fixtures/valid/valid-heading-like-number-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+## L7

test/fixtures/valid/valid-heading-like-number-fragment/valid-heading-like-number-fragment.md

@@ -0,0 +1,3 @@
+# Valid
+
+[Link fragment](./awesome.md#l7)

test/fixtures/valid/valid-line-column-range-number-fragment/awesome.md

@@ -0,0 +1,3 @@
+# Awesome
+
+## L12 Not A Line Link

test/fixtures/valid/valid-line-column-range-number-fragment/valid-line-column-range-number-fragment.md

@@ -0,0 +1,11 @@
+# Valid
+
+[Valid](./awesome.md#l12-not-a-line-link)
+
+[Valid](./awesome.md#L30-L31)
+
+[Valid](./awesome.md#L3C24-L88)
+
+[Valid](./awesome.md#L304-L314C98)
+
+[Valid](./awesome.md#L200C4-L3244C2)

test/fixtures/valid/valid-line-number-fragment/awesome.md

@@ -0,0 +1,9 @@
+# Awesome
+
+ABC
+
+Line 5
+
+Line 7 Text
+
+## L7

test/fixtures/valid/valid-line-number-fragment/valid-line-number-fragment.md

@@ -0,0 +1,3 @@
+# Valid
+
+[Link fragment line number 7](./awesome.md#L7)

test/index.test.js

@@ -0,0 +1,247 @@
+const { test } = require("node:test")
+const assert = require("node:assert/strict")
+
+const { markdownlint } = require("markdownlint").promises
+
+const relativeLinksRule = require("../src/index.js")
+
+/**
+ *
+ * @param {string} fixtureFile
+ * @returns
+ */
+const validateMarkdownLint = async (fixtureFile) => {
+  const lintResults = await markdownlint({
+    files: [fixtureFile],
+    config: {
+      default: false,
+      "relative-links": true,
+    },
+    customRules: [relativeLinksRule],
+  })
+  return lintResults[fixtureFile]
+}
+
+test("ensure the rule validates correctly", async (t) => {
+  await t.test("should be invalid", async (t) => {
+    const testCases = [
+      {
+        name: "should be invalid with an empty id fragment",
+        fixturePath:
+          "test/fixtures/invalid/empty-id-fragment/empty-id-fragment.md",
+        errors: ['"./awesome.md#" should have a valid fragment identifier'],
+      },
+      {
+        name: "should be invalid with a name fragment other than for an anchor",
+        fixturePath:
+          "test/fixtures/invalid/ignore-name-fragment-if-not-an-anchor/ignore-name-fragment-if-not-an-anchor.md",
+        errors: [
+          '"./awesome.md#name-should-be-ignored" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a non-existing id fragment (data-id !== id)",
+        fixturePath:
+          "test/fixtures/invalid/ignore-not-an-id-fragment/ignore-not-an-id-fragment.md",
+        errors: [
+          '"./awesome.md#not-an-id-should-be-ignored" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with uppercase letters in fragment (case sensitive)",
+        fixturePath:
+          "test/fixtures/invalid/invalid-heading-case-sensitive/invalid-heading-case-sensitive.md",
+        errors: [
+          '"./awesome.md#ExistIng-Heading" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with invalid heading with #L fragment",
+        fixturePath:
+          "test/fixtures/invalid/invalid-heading-with-L-fragment/invalid-heading-with-L-fragment.md",
+        errors: [
+          '"./awesome.md#L7abc" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a invalid line column range number fragment",
+        fixturePath:
+          "test/fixtures/invalid/invalid-line-column-range-number-fragment/invalid-line-column-range-number-fragment.md",
+        errors: [
+          '"./awesome.md#L12-not-a-line-link" should have a valid fragment identifier',
+          '"./awesome.md#l7" should have a valid fragment identifier',
+          '"./awesome.md#L" should have a valid fragment identifier',
+          '"./awesome.md#L7extra" should have a valid fragment identifier',
+          '"./awesome.md#L30C" should have a valid fragment identifier',
+          '"./awesome.md#L30Cextra" should have a valid fragment identifier',
+          '"./awesome.md#L30L12" should have a valid fragment identifier',
+          '"./awesome.md#L30C12" should have a valid fragment identifier',
+          '"./awesome.md#L30C11-" should have a valid fragment identifier',
+          '"./awesome.md#L30C11-L" should have a valid fragment identifier',
+          '"./awesome.md#L30C11-L31C" should have a valid fragment identifier',
+          '"./awesome.md#L30C11-C31" should have a valid fragment identifier',
+          '"./awesome.md#C30" should have a valid fragment identifier',
+          '"./awesome.md#C11-C31" should have a valid fragment identifier',
+          '"./awesome.md#C11-L4C31" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a invalid line number fragment",
+        fixturePath:
+          "test/fixtures/invalid/invalid-line-number-fragment/invalid-line-number-fragment.md",
+        errors: [
+          '"./awesome.md#L7" should have a valid fragment identifier, "./awesome.md#L7" should have at least 7 lines to be valid',
+        ],
+      },
+      {
+        name: "should be invalid with a non-existing anchor name fragment",
+        fixturePath:
+          "test/fixtures/invalid/non-existing-anchor-name-fragment/non-existing-anchor-name-fragment.md",
+        errors: [
+          '"./awesome.md#non-existing-anchor-name-fragment" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a non-existing element id fragment",
+        fixturePath:
+          "test/fixtures/invalid/non-existing-element-id-fragment/non-existing-element-id-fragment.md",
+        errors: [
+          '"./awesome.md#non-existing-element-id-fragment" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a non-existing heading fragment",
+        fixturePath:
+          "test/fixtures/invalid/non-existing-heading-fragment/non-existing-heading-fragment.md",
+        errors: [
+          '"./awesome.md#non-existing-heading" should have a valid fragment identifier',
+        ],
+      },
+      {
+        name: "should be invalid with a link to an image with a empty fragment",
+        fixturePath:
+          "test/fixtures/invalid/ignore-empty-fragment-checking-for-image.md",
+        errors: [
+          '"../image.png#" should not have a fragment identifier as it is an image',
+        ],
+      },
+      {
+        name: "should be invalid with a link to an image with a fragment",
+        fixturePath:
+          "test/fixtures/invalid/ignore-fragment-checking-for-image.md",
+        errors: [
+          '"../image.png#non-existing-fragment" should not have a fragment identifier as it is an image',
+        ],
+      },
+      {
+        name: "should be invalid with a non-existing file",
+        fixturePath: "test/fixtures/invalid/non-existing-file.md",
+        errors: ['"./index.test.js" should exist in the file system'],
+      },
+      {
+        name: "should be invalid with a non-existing image",
+        fixturePath: "test/fixtures/invalid/non-existing-image.md",
+        errors: ['"./image.png" should exist in the file system'],
+      },
+    ]
+
+    for (const { name, fixturePath, errors } of testCases) {
+      await t.test(name, async () => {
+        const lintResults = (await validateMarkdownLint(fixturePath)) ?? []
+        const errorsDetails = lintResults.map((result) => {
+          assert.deepEqual(result.ruleNames, relativeLinksRule.names)
+          assert.deepEqual(
+            result.ruleDescription,
+            relativeLinksRule.description,
+          )
+          return result.errorDetail
+        })
+        assert.deepStrictEqual(
+          errorsDetails,
+          errors,
+          `${fixturePath}: Expected errors`,
+        )
+      })
+    }
+  })
+
+  await t.test("should be valid", async (t) => {
+    const testCases = [
+      {
+        name: "should be valid with an existing anchor name fragment",
+        fixturePath:
+          "test/fixtures/valid/existing-anchor-name-fragment/existing-anchor-name-fragment.md",
+      },
+      {
+        name: "should be valid with an existing element id fragment",
+        fixturePath:
+          "test/fixtures/valid/existing-element-id-fragment/existing-element-id-fragment.md",
+      },
+      {
+        name: "should be valid with an existing heading fragment",
+        fixturePath:
+          "test/fixtures/valid/existing-heading-fragment/existing-heading-fragment.md",
+      },
+      {
+        name: 'should be valid with an existing heading fragment with accents (e.g: "é")',
+        fixturePath:
+          "test/fixtures/valid/existing-heading-with-accents/existing-heading-with-accents.md",
+      },
+      {
+        name: "should only parse markdown files for fragments checking",
+        fixturePath:
+          "test/fixtures/valid/only-parse-markdown-files-for-fragments/only-parse-markdown-files-for-fragments.md",
+      },
+      {
+        name: "should support lines and columns range numbers in link fragments",
+        fixturePath:
+          "test/fixtures/valid/valid-line-column-range-number-fragment/valid-line-column-range-number-fragment.md",
+      },
+      {
+        name: 'should be valid with valid heading "like" line number fragment',
+        fixturePath:
+          "test/fixtures/valid/valid-heading-like-number-fragment/valid-heading-like-number-fragment.md",
+      },
+      {
+        name: "should be valid with valid line number fragment",
+        fixturePath:
+          "test/fixtures/valid/valid-line-number-fragment/valid-line-number-fragment.md",
+      },
+      {
+        name: "should be valid with an existing file",
+        fixturePath: "test/fixtures/valid/existing-file.md",
+      },
+      {
+        name: "should be valid with an existing image",
+        fixturePath: "test/fixtures/valid/existing-image.md",
+      },
+      {
+        name: "should ignore absolute paths",
+        fixturePath: "test/fixtures/valid/ignore-absolute-paths.md",
+      },
+      {
+        name: "should ignore external links",
+        fixturePath: "test/fixtures/valid/ignore-external-links.md",
+      },
+      {
+        name: "should ignore checking fragment in own file",
+        fixturePath:
+          "test/fixtures/valid/ignore-fragment-checking-in-own-file.md",
+      },
+    ]
+
+    for (const { name, fixturePath } of testCases) {
+      await t.test(name, async () => {
+        const lintResults = (await validateMarkdownLint(fixturePath)) ?? []
+        const errorsDetails = lintResults.map((result) => {
+          return result.errorDetail
+        })
+        assert.equal(
+          errorsDetails.length,
+          0,
+          `${fixturePath}: Expected no errors, got ${errorsDetails.join(", ")}`,
+        )
+      })
+    }
+  })
+})

test/utils.test.js

@@ -0,0 +1,79 @@
+const { test } = require("node:test")
+const assert = require("node:assert/strict")
+
+const {
+  convertHeadingToHTMLFragment,
+  getMarkdownHeadings,
+  getMarkdownIdOrAnchorNameFragments,
+  isValidIntegerString,
+  getNumberOfLines,
+  getLineNumberStringFromFragment,
+} = require("../src/utils.js")
+
+test("utils", async (t) => {
+  await t.test("convertHeadingToHTMLFragment", async () => {
+    assert.strictEqual(
+      convertHeadingToHTMLFragment("Valid Fragments"),
+      "#valid-fragments",
+    )
+    assert.strictEqual(
+      convertHeadingToHTMLFragment("Valid Heading With Underscores _"),
+      "#valid-heading-with-underscores-_",
+    )
+    assert.strictEqual(
+      convertHeadingToHTMLFragment(
+        `Valid Heading With Quotes ' And Double Quotes "`,
+      ),
+      "#valid-heading-with-quotes--and-double-quotes-",
+    )
+    assert.strictEqual(
+      convertHeadingToHTMLFragment("🚀 Valid Heading With Emoji"),
+      "#-valid-heading-with-emoji",
+    )
+  })
+
+  await t.test("getMarkdownHeadings", async () => {
+    assert.deepStrictEqual(
+      getMarkdownHeadings("# Hello\n\n## World\n\n## Hello, world!\n"),
+      ["Hello", "World", "Hello, world!"],
+    )
+  })
+
+  await t.test("getMarkdownIdOrAnchorNameFragments", async () => {
+    assert.deepStrictEqual(
+      getMarkdownIdOrAnchorNameFragments(
+        '<a name="anchorName" id="anchorId">Link</a>',
+      ),
+      ["#anchorId"],
+    )
+    assert.deepStrictEqual(
+      getMarkdownIdOrAnchorNameFragments('<a name="anchorName">Link</a>'),
+      ["#anchorName"],
+    )
+    assert.deepStrictEqual(
+      getMarkdownIdOrAnchorNameFragments("<a>Link</a>"),
+      [],
+    )
+    assert.deepStrictEqual(getMarkdownIdOrAnchorNameFragments("<a>"), [])
+    assert.deepStrictEqual(getMarkdownIdOrAnchorNameFragments("<a id=>"), [])
+  })
+
+  await t.test("isValidIntegerString", async () => {
+    assert.strictEqual(isValidIntegerString("1"), true)
+    assert.strictEqual(isValidIntegerString("45"), true)
+    assert.strictEqual(isValidIntegerString("1abc"), false)
+    assert.strictEqual(isValidIntegerString("1.0"), false)
+  })
+
+  await t.test("getNumberOfLines", async () => {
+    assert.strictEqual(getNumberOfLines(""), 1)
+    assert.strictEqual(getNumberOfLines("Hello"), 1)
+    assert.strictEqual(getNumberOfLines("Hello\nWorld"), 2)
+    assert.strictEqual(getNumberOfLines("Hello\nWorld\n"), 3)
+    assert.strictEqual(getNumberOfLines("Hello\nWorld\n\n"), 4)
+  })
+
+  await t.test("getLineNumberStringFromFragment", async () => {
+    assert.strictEqual(getLineNumberStringFromFragment("#L50"), "50")
+  })
+})