diff --git a/package.json b/package.json
index 4ccbf626..18a7d6fa 100644
--- a/package.json
+++ b/package.json
@@ -81,6 +81,7 @@
   },
   "devDependencies": {
     "@arethetypeswrong/cli": "^0.18.3",
+    "@eslint-markdown/parser": "^0.0.0-canary.3",
     "@eslint/js": "^10.0.1",
     "@eslint/json": "^2.0.1",
     "@types/mdast": "^4.0.4",
diff --git a/src/language/markdown-language.js b/src/language/markdown-language.js
index 12cc528b..96ccff78 100644
--- a/src/language/markdown-language.js
+++ b/src/language/markdown-language.js
@@ -26,10 +26,9 @@ import { math } from "micromark-extension-math";
  * @import { Language, File, ParseResult, OkParseResult } from "@eslint/core";
  * @import { Root } from "mdast";
  * @import { Options } from "mdast-util-from-markdown";
- * @import { MarkdownLanguageOptions, MarkdownLanguageContext } from "../types.js";
+ * @import { MarkdownLanguageOptions, MarkdownLanguageContext, MarkdownParserMode } from "../types.js";
  * @typedef {Options['extensions']} Extensions
  * @typedef {Options['mdastExtensions']} MdastExtensions
- * @typedef {"commonmark"|"gfm"} ParserMode
  */
 
 //-----------------------------------------------------------------------------
@@ -55,7 +54,7 @@ const jsonFrontmatterConfig = {
 
 /**
  * Create parser options based on `mode` and `languageOptions`.
- * @param {ParserMode} mode The markdown parser mode.
+ * @param {MarkdownParserMode} mode The markdown parser mode.
  * @param {MarkdownLanguageOptions} languageOptions Language options.
  * @returns {{extensions: Extensions, mdastExtensions: MdastExtensions}} Parser options for micromark and mdast.
  */
@@ -145,18 +144,29 @@ export class MarkdownLanguage {
 	defaultLanguageOptions = {
 		frontmatter: false,
 		math: false,
+		parser: {
+			meta: {
+				name: "mdast-util-from-markdown",
+			},
+			parse(text, { mode, ...languageOptions }) {
+				return fromMarkdown(
+					text,
+					createParserOptions(mode, languageOptions),
+				);
+			},
+		},
 	};
 
 	/**
 	 * The Markdown parser mode.
-	 * @type {ParserMode}
+	 * @type {MarkdownParserMode}
 	 */
 	#mode = "commonmark";
 
 	/**
 	 * Creates a new instance.
-	 * @param {Object} options The options to use for this instance.
-	 * @param {ParserMode} [options.mode] The Markdown parser mode to use.
+	 * @param {Object} [options] The options to use for this instance.
+	 * @param {MarkdownParserMode} [options.mode] The Markdown parser mode to use.
 	 */
 	constructor({ mode } = {}) {
 		if (mode) {
@@ -166,7 +176,7 @@ export class MarkdownLanguage {
 
 	/**
 	 * Validates the language options.
-	 * @param {MarkdownLanguageOptions} languageOptions The language options to validate.
+	 * @param {MarkdownLanguageOptions} [languageOptions] The language options to validate.
 	 * @returns {void}
 	 * @throws {Error} When the language options are invalid.
 	 */
@@ -197,18 +207,40 @@ export class MarkdownLanguage {
 				`Invalid language option value \`${mathOption}\` for math. Expected a boolean.`,
 			);
 		}
+
+		// `parser` option validation
+		const parserOption = languageOptions?.parser;
+
+		if (parserOption !== undefined) {
+			if (typeof parserOption !== "object" || parserOption === null) {
+				throw new Error(
+					`Invalid language option value \`${String(parserOption)}\` for parser. Expected a non-null object.`,
+				);
+			}
+
+			if (typeof parserOption.parse !== "function") {
+				throw new Error(
+					"Invalid language option `parser`. Expected an object with a `parse` method.",
+				);
+			}
+		}
 	}
 
 	/**
 	 * Parses the given file into an AST.
 	 * @param {File} file The virtual file to parse.
-	 * @param {MarkdownLanguageContext} context The options to use for parsing.
+	 * @param {MarkdownLanguageContext} [context] The options to use for parsing.
 	 * @returns {ParseResult<Root>} The result of parsing.
 	 */
 	parse(file, context) {
 		// Note: BOM already removed
 		const text = /** @type {string} */ (file.body);
 
+		const {
+			parser = this.defaultLanguageOptions.parser,
+			...restLanguageOptions
+		} = context?.languageOptions ?? {};
+
 		/*
 		 * Check for parsing errors first. If there's a parsing error, nothing
 		 * else can happen. However, a parsing error does not throw an error
@@ -216,11 +248,10 @@ export class MarkdownLanguage {
 		 * problem that ESLint identified just like any other.
 		 */
 		try {
-			const options = createParserOptions(
-				this.#mode,
-				context?.languageOptions,
-			);
-			const root = fromMarkdown(text, options);
+			const root = parser.parse(text, {
+				...restLanguageOptions,
+				mode: this.#mode,
+			});
 
 			return {
 				ok: true,
diff --git a/src/types.ts b/src/types.ts
index fcd77a5d..12b561d2 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -42,6 +42,7 @@ import type { InlineMath, Math } from "mdast-util-math";
 import type {
 	LanguageContext,
 	LanguageOptions,
+	ObjectMetaProperties,
 	RuleVisitor,
 } from "@eslint/core";
 import type {
@@ -133,6 +134,51 @@ declare module "mdast" {
 // Exports: Language and Source Code
 //------------------------------------------------------------------------------
 
+/**
+ * @deprecated Use `MarkdownParserMode` instead.
+ */
+export type ParserMode = MarkdownParserMode;
+
+/**
+ * The mode of the Markdown parser to use.
+ * @default "commonmark"
+ */
+export type MarkdownParserMode = "commonmark" | "gfm";
+
+/**
+ * A parser that converts Markdown source text into an
+ * [mdast](https://github.com/syntax-tree/mdast#readme) syntax tree.
+ */
+export type MarkdownParser = ObjectMetaProperties & {
+	/**
+	 * Parses Markdown source text into an
+	 * [mdast](https://github.com/syntax-tree/mdast#readme) syntax tree.
+	 * @param text The Markdown source text to parse.
+	 * @param options The parser-specific options.
+	 * @returns The root of the mdast syntax tree.
+	 */
+	parse(
+		text: string,
+		options: MarkdownLanguageOptions & {
+			/**
+			 * The mode of the Markdown parser to use.
+			 * @default "commonmark"
+			 */
+			mode: MarkdownParserMode;
+
+			/*
+			 * Don't use `Omit<MarkdownLanguageOptions, "parser">` here.
+			 * Because `MarkdownLanguageOptions` has a string index signature,
+			 * `Omit` would lose its named option properties.
+			 */
+			/**
+			 * Parsers cannot override the `parser` used by the language.
+			 */
+			parser?: never;
+		},
+	): Root;
+};
+
 /**
  * Language options provided for Markdown files.
  */
@@ -148,6 +194,12 @@ export interface MarkdownLanguageOptions extends LanguageOptions {
 	 * @default false
 	 */
 	math?: boolean;
+
+	/**
+	 * An object with a `parse()` method and optional metadata properties.
+	 * If not configured, the default ESLint Markdown parser (`mdast-util-from-markdown`) will be used.
+	 */
+	parser?: MarkdownParser;
 }
 
 /**
diff --git a/tests/fixtures/parser.js b/tests/fixtures/parser.js
new file mode 100644
index 00000000..ebbc7234
--- /dev/null
+++ b/tests/fixtures/parser.js
@@ -0,0 +1,21 @@
+import markdown from "../../src/index.js";
+
+export default [
+	{
+		files: ["**/*.md"],
+		plugins: { markdown },
+		language: "markdown/commonmark",
+		languageOptions: {
+			parser: {
+				parse() {
+					throw new Error(
+						"The configured Markdown parser was called.",
+					);
+				},
+			},
+		},
+		rules: {
+			"markdown/heading-increment": "error",
+		},
+	},
+];
diff --git a/tests/language/markdown-language.test.js b/tests/language/markdown-language.test.js
index b9c5c4cf..ca9ea148 100644
--- a/tests/language/markdown-language.test.js
+++ b/tests/language/markdown-language.test.js
@@ -139,6 +139,22 @@ describe("MarkdownLanguage", () => {
 				language.validateLanguageOptions({ math: false });
 			});
 		});
+
+		it("should throw the expected error when `parser` is a symbol", () => {
+			const language = new MarkdownLanguage();
+
+			assert.throws(
+				() => {
+					language.validateLanguageOptions({
+						parser: Symbol("parser"),
+					});
+				},
+				{
+					message:
+						"Invalid language option value `Symbol(parser)` for parser. Expected a non-null object.",
+				},
+			);
+		});
 	});
 
 	describe("parse()", () => {
@@ -402,6 +418,26 @@ describe("MarkdownLanguage", () => {
 			assert.strictEqual(result.ast.children[1].children[0].type, "text");
 			assert.strictEqual(result.ast.children[2].type, "math");
 		});
+
+		it("should not allow language options to override commonmark mode", () => {
+			const language = new MarkdownLanguage({
+				mode: "commonmark",
+			});
+			const result = language.parse(
+				{
+					body: "| Column 1 | Column 2 |\n| -------- | -------- |\n| Cell 1   | Cell 2   |",
+					path: "test.md",
+				},
+				{
+					languageOptions: {
+						mode: "gfm",
+					},
+				},
+			);
+
+			assert.strictEqual(result.ok, true);
+			assert.strictEqual(result.ast.children[0].type, "paragraph");
+		});
 	});
 
 	describe("createSourceCode()", () => {
diff --git a/tests/plugin.test.js b/tests/plugin.test.js
index ac88c6d4..86a5c600 100644
--- a/tests/plugin.test.js
+++ b/tests/plugin.test.js
@@ -8,6 +8,7 @@
 //-----------------------------------------------------------------------------
 
 import assert from "node:assert";
+import { spawnSync } from "node:child_process";
 import path from "node:path";
 import fs from "node:fs";
 import { fileURLToPath, pathToFileURL } from "node:url";
@@ -1228,6 +1229,25 @@ describe("FlatESLint", () => {
 				.map(([name]) => `markdown/${name}`);
 			assert.deepStrictEqual(actualRuleIds, expectedRuleIds);
 		});
+
+		it("should serialize the default Markdown parser", async () => {
+			const markdownESLint = new ESLint({
+				overrideConfigFile: true,
+				overrideConfig: {
+					files: ["**/*.md"],
+					plugins: { markdown: plugin },
+					language: "markdown/commonmark",
+				},
+			});
+			const config =
+				await markdownESLint.calculateConfigForFile("test.md");
+			const serializedConfig = JSON.parse(JSON.stringify(config));
+
+			assert.strictEqual(
+				serializedConfig.languageOptions.parser,
+				"mdast-util-from-markdown",
+			);
+		});
 	});
 
 	describe("plugin", () => {
@@ -2440,4 +2460,53 @@ describe("FlatESLint", () => {
 			}
 		});
 	});
+
+	describe("CLI", () => {
+		it("should override the Markdown parser with `--parser @eslint-markdown/parser`", () => {
+			const eslintPath = fileURLToPath(
+				new URL(
+					"bin/eslint.js",
+					import.meta.resolve("eslint/package.json"),
+				),
+			);
+			const args = [
+				eslintPath,
+				"--config=parser.js",
+				"--stdin",
+				"--stdin-filename=test.md",
+				"--format=json",
+			];
+			const options = {
+				cwd: path.resolve(__dirname, "fixtures"),
+				input: "# Hello\n\n### Skipped level\n",
+				encoding: "utf8",
+			};
+
+			const withoutParser = spawnSync(process.execPath, args, options);
+
+			assert.strictEqual(withoutParser.status, 1);
+			const [configuredResult] = JSON.parse(withoutParser.stdout);
+
+			assert.strictEqual(configuredResult.messages.length, 1);
+			assert.strictEqual(
+				configuredResult.messages[0].message,
+				"Parsing error: The configured Markdown parser was called.",
+			);
+
+			const withParser = spawnSync(
+				process.execPath,
+				[...args, "--parser", "@eslint-markdown/parser"],
+				options,
+			);
+
+			assert.strictEqual(withParser.status, 1);
+			const [overriddenResult] = JSON.parse(withParser.stdout);
+
+			assert.strictEqual(overriddenResult.messages.length, 1);
+			assert.strictEqual(
+				overriddenResult.messages[0].ruleId,
+				"markdown/heading-increment",
+			);
+		});
+	});
 });
diff --git a/tests/rules/_utils/rule-tester.js b/tests/rules/_utils/rule-tester.js
new file mode 100644
index 00000000..ae832a38
--- /dev/null
+++ b/tests/rules/_utils/rule-tester.js
@@ -0,0 +1,101 @@
+/**
+ * @fileoverview A rule tester helper for running code with both `mdast-util-from-markdown` and `@eslint-markdown/parser`.
+ * @author lumir(lumirlumir)
+ */
+
+// --------------------------------------------------------------------------------
+// Imports
+// --------------------------------------------------------------------------------
+
+import parser from "@eslint-markdown/parser";
+import { RuleTester } from "eslint";
+import markdown from "../../../src/index.js";
+
+//------------------------------------------------------------------------------
+// Typedefs
+//------------------------------------------------------------------------------
+
+/**
+ * @import { MarkdownRuleDefinition } from "../../../src/types.ts";
+ */
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Creates a new `RuleTester` instance with the `mdast-util-from-markdown` JS parser and CommonMark syntax.
+ */
+const ruleTesterJSCommonMark = new RuleTester({
+	plugins: {
+		markdown,
+	},
+	language: "markdown/commonmark",
+});
+
+/**
+ * Creates a new `RuleTester` instance with the `mdast-util-from-markdown` JS parser and GFM syntax.
+ */
+const ruleTesterJSGFM = new RuleTester({
+	plugins: {
+		markdown,
+	},
+	language: "markdown/gfm",
+});
+
+/**
+ * Creates a new `RuleTester` instance with the `@eslint-markdown/parser` Rust parser and CommonMark syntax.
+ */
+const ruleTesterRustCommonMark = new RuleTester({
+	plugins: {
+		markdown,
+	},
+	language: "markdown/commonmark",
+	languageOptions: {
+		parser,
+	},
+});
+
+/**
+ * Creates a new `RuleTester` instance with the `@eslint-markdown/parser` Rust parser and GFM syntax.
+ */
+const ruleTesterRustGFM = new RuleTester({
+	plugins: {
+		markdown,
+	},
+	language: "markdown/gfm",
+	languageOptions: {
+		parser,
+	},
+});
+
+//------------------------------------------------------------------------------
+// Exports
+//------------------------------------------------------------------------------
+
+/**
+ * Markdown rule tester.
+ * @param {string} ruleName Rule name.
+ * @param {MarkdownRuleDefinition} rule Rule definition.
+ * @param {Parameters<RuleTester['run']>[2]} tests Test cases.
+ * @returns {void}
+ */
+export default function ruleTester(ruleName, rule, tests) {
+	describe("JS: mdast-util-from-markdown", () => {
+		describe("CommonMark", () => {
+			ruleTesterJSCommonMark.run(ruleName, rule, tests);
+		});
+		describe("GFM", () => {
+			ruleTesterJSGFM.run(ruleName, rule, tests);
+		});
+	});
+
+	describe("Rust: @eslint-markdown/parser", () => {
+		describe("CommonMark", () => {
+			ruleTesterRustCommonMark.run(ruleName, rule, tests);
+		});
+		describe("GFM", () => {
+			ruleTesterRustGFM.run(ruleName, rule, tests);
+		});
+	});
+}
diff --git a/tests/rules/fenced-code-language.test.js b/tests/rules/fenced-code-language.test.js
index 8540a6ca..0632c5e9 100644
--- a/tests/rules/fenced-code-language.test.js
+++ b/tests/rules/fenced-code-language.test.js
@@ -7,22 +7,14 @@
 // Imports
 //------------------------------------------------------------------------------
 
+import ruleTester from "./_utils/rule-tester.js";
 import rule from "../../src/rules/fenced-code-language.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/commonmark",
-});
-
-ruleTester.run("fenced-code-language", rule, {
+ruleTester("fenced-code-language", rule, {
 	valid: [
 		// backtick code block
 		`\`\`\`js
diff --git a/tests/rules/fenced-code-meta.test.js b/tests/rules/fenced-code-meta.test.js
index ab017483..1dade856 100644
--- a/tests/rules/fenced-code-meta.test.js
+++ b/tests/rules/fenced-code-meta.test.js
@@ -7,23 +7,15 @@
 // Imports
 //------------------------------------------------------------------------------
 
-import rule from "../../src/rules/fenced-code-meta.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 import dedent from "dedent";
+import ruleTester from "./_utils/rule-tester.js";
+import rule from "../../src/rules/fenced-code-meta.js";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/commonmark",
-});
-
-ruleTester.run("fenced-code-meta", rule, {
+ruleTester("fenced-code-meta", rule, {
 	valid: [
 		dedent`\`\`\`
 		console.log("Hello, world!");
diff --git a/tests/rules/heading-increment.test.js b/tests/rules/heading-increment.test.js
index adc3b1de..640b2590 100644
--- a/tests/rules/heading-increment.test.js
+++ b/tests/rules/heading-increment.test.js
@@ -7,23 +7,15 @@
 // Imports
 //------------------------------------------------------------------------------
 
-import rule from "../../src/rules/heading-increment.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 import dedent from "dedent";
+import ruleTester from "./_utils/rule-tester.js";
+import rule from "../../src/rules/heading-increment.js";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/commonmark",
-});
-
-ruleTester.run("heading-increment", rule, {
+ruleTester("heading-increment", rule, {
 	valid: [
 		"# Heading 1",
 		"## Heading 2",
diff --git a/tests/rules/no-bare-urls.test.js b/tests/rules/no-bare-urls.test.js
index df9d171b..aa219cae 100644
--- a/tests/rules/no-bare-urls.test.js
+++ b/tests/rules/no-bare-urls.test.js
@@ -23,6 +23,8 @@ const ruleTester = new RuleTester({
 	language: "markdown/gfm",
 });
 
+// TODO
+
 ruleTester.run("no-bare-urls", rule, {
 	valid: [
 		"<https://www.google.com/>",
diff --git a/tests/rules/no-duplicate-definitions.test.js b/tests/rules/no-duplicate-definitions.test.js
index 47fd4d66..1dcc9b44 100644
--- a/tests/rules/no-duplicate-definitions.test.js
+++ b/tests/rules/no-duplicate-definitions.test.js
@@ -7,22 +7,14 @@
 // Imports
 //------------------------------------------------------------------------------
 
+import ruleTester from "./_utils/rule-tester.js";
 import rule from "../../src/rules/no-duplicate-definitions.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/gfm",
-});
-
-ruleTester.run("no-duplicate-definitions", rule, {
+ruleTester("no-duplicate-definitions", rule, {
 	valid: [
 		`
 [mercury]: https://example.com/mercury/
@@ -33,20 +25,29 @@ ruleTester.run("no-duplicate-definitions", rule, {
 [venus]: https://example.com/venus/
 `,
 
-		`
+		{
+			code: `
 [^mercury]: Hello, Mercury!
 `,
+			language: "markdown/gfm",
+		},
 
-		`
+		{
+			code: `
 [^mercury]: Hello, Mercury!
 [^venus]: Hello, Venus!
 `,
+			language: "markdown/gfm",
+		},
 
-		`
+		{
+			code: `
 [alpha]: bravo
 
 [^alpha]: bravo
 `,
+			language: "markdown/gfm",
+		},
 
 		`
 [//]: # (This is a comment 1)
@@ -70,6 +71,7 @@ ruleTester.run("no-duplicate-definitions", rule, {
 [^mercury]: Hello, Mercury!
 [^mercury]: Hello, Venus!
 `,
+			language: "markdown/gfm",
 			options: [
 				{
 					allowFootnoteDefinitions: ["mercury"],
@@ -136,6 +138,7 @@ ruleTester.run("no-duplicate-definitions", rule, {
 [^MERCURY]: Hello, Mercury!
 [^mercury]: Hello, Venus!
 `,
+			language: "markdown/gfm",
 			options: [
 				{
 					allowFootnoteDefinitions: ["MERCURY"],
@@ -147,6 +150,7 @@ ruleTester.run("no-duplicate-definitions", rule, {
 [^mercury]: Hello, Mercury!
 [^MERCURY]: Hello, Venus!
 `,
+			language: "markdown/gfm",
 			options: [
 				{
 					allowFootnoteDefinitions: ["mercury"],
@@ -158,6 +162,7 @@ ruleTester.run("no-duplicate-definitions", rule, {
 [^mercury]: Hello, Mercury!
 [^mercury]: Hello, Venus!
 `,
+			language: "markdown/gfm",
 			options: [
 				{
 					checkFootnoteDefinitions: false,
@@ -169,6 +174,7 @@ ruleTester.run("no-duplicate-definitions", rule, {
 [^mercury]: Hello, Mercury!
 [^mercury]: Hello, Venus!
 `,
+			language: "markdown/gfm",
 			options: [
 				{
 					checkFootnoteDefinitions: true,
@@ -191,6 +197,7 @@ ruleTester.run("no-duplicate-definitions", rule, {
 						[^Grüsse]: Grüsse
 						[^Grüsse]: Grüsse
 						`,
+						language: "markdown/gfm",
 						options: [{ allowFootnoteDefinitions: ["GRÜẞE"] }],
 					},
 				]
@@ -348,6 +355,7 @@ ruleTester.run("no-duplicate-definitions", rule, {
 [^mercury]: Hello, Mercury!
 [^mercury]: Hello, Venus!
 `,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "duplicateFootnoteDefinition",
@@ -372,6 +380,7 @@ ruleTester.run("no-duplicate-definitions", rule, {
 [^mercury]: Hello, Earth!
 [^mercury]: Hello, Mars!
 `,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "duplicateFootnoteDefinition",
@@ -420,6 +429,7 @@ ruleTester.run("no-duplicate-definitions", rule, {
 [^mercury]: Hello, Mercury!
 [^Mercury]: Hello, Venus!
 `, // case insensitive
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "duplicateFootnoteDefinition",
@@ -442,6 +452,7 @@ ruleTester.run("no-duplicate-definitions", rule, {
 [^mercury]: Hello, Mercury!
 [^mercury]: Hello, Venus!
 `,
+			language: "markdown/gfm",
 			options: [
 				{
 					allowDefinitions: ["mercury"],
@@ -471,6 +482,7 @@ ruleTester.run("no-duplicate-definitions", rule, {
 [^mercury]: Hello, Mercury!
 [^mercury]: Hello, Venus!
 `,
+			language: "markdown/gfm",
 			options: [
 				{
 					checkFootnoteDefinitions: true,
diff --git a/tests/rules/no-duplicate-headings.test.js b/tests/rules/no-duplicate-headings.test.js
index 39b1b5cd..9172a1a0 100644
--- a/tests/rules/no-duplicate-headings.test.js
+++ b/tests/rules/no-duplicate-headings.test.js
@@ -7,23 +7,17 @@
 // Imports
 //------------------------------------------------------------------------------
 
-import rule from "../../src/rules/no-duplicate-headings.js";
-import markdown from "../../src/index.js";
-import { Linter, RuleTester } from "eslint";
+import { Linter } from "eslint";
 import dedent from "dedent";
+import ruleTester from "./_utils/rule-tester.js";
+import markdown from "../../src/index.js";
+import rule from "../../src/rules/no-duplicate-headings.js";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/commonmark",
-});
-
-ruleTester.run("no-duplicate-headings", rule, {
+ruleTester("no-duplicate-headings", rule, {
 	valid: [
 		// Using emphasis in headings should not be considered a duplicate by default.
 		dedent`
diff --git a/tests/rules/no-empty-definitions.test.js b/tests/rules/no-empty-definitions.test.js
index f98797f3..7528207a 100644
--- a/tests/rules/no-empty-definitions.test.js
+++ b/tests/rules/no-empty-definitions.test.js
@@ -7,23 +7,15 @@
 // Imports
 //------------------------------------------------------------------------------
 
-import rule from "../../src/rules/no-empty-definitions.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 import dedent from "dedent";
+import ruleTester from "./_utils/rule-tester.js";
+import rule from "../../src/rules/no-empty-definitions.js";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/gfm",
-});
-
-ruleTester.run("no-empty-definitions", rule, {
+ruleTester("no-empty-definitions", rule, {
 	valid: [
 		"[foo]: bar",
 		"[foo]: #bar",
@@ -31,24 +23,57 @@ ruleTester.run("no-empty-definitions", rule, {
 		"[foo]: <https://bar.com>",
 		"[//]: # (This is a comment 1)",
 		"[//]: <> (This is a comment 2)",
-		"[^note]: This is a footnote.",
-		"[^note]: ![]()",
-		"[^note]: [text](url)",
-		"[^note]:\n    Content",
-		"[^note]:\n    > blockquote",
-		"[^note]: <span></span>",
+		{
+			code: "[^note]: This is a footnote.",
+			language: "markdown/gfm",
+		},
+		{
+			code: "[^note]: ![]()",
+			language: "markdown/gfm",
+		},
+		{
+			code: "[^note]: [text](url)",
+			language: "markdown/gfm",
+		},
+		{
+			code: "[^note]:\n    Content",
+			language: "markdown/gfm",
+		},
+		{
+			code: "[^note]:\n    > blockquote",
+			language: "markdown/gfm",
+		},
+		{
+			code: "[^note]: <span></span>",
+			language: "markdown/gfm",
+		},
 		"\\[^note]:",
 		"[\\^note]:",
 		"[^note\\]:",
 		"[^note]\\:",
-		"[^foo]: <span></span> <!-- comment -->",
-		"[^foo]: content <!-- comment -->",
-		"[^foo]: <!-- comment --> content",
-		"[^foo]: <!-- comment --> content <!-- comment -->",
-		dedent`
-		[^foo]: <!-- comm
-		    ent --> content <!-- comment -->
-		`,
+		{
+			code: "[^foo]: <span></span> <!-- comment -->",
+			language: "markdown/gfm",
+		},
+		{
+			code: "[^foo]: content <!-- comment -->",
+			language: "markdown/gfm",
+		},
+		{
+			code: "[^foo]: <!-- comment --> content",
+			language: "markdown/gfm",
+		},
+		{
+			code: "[^foo]: <!-- comment --> content <!-- comment -->",
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
+			[^foo]: <!-- comm
+			    ent --> content <!-- comment -->
+			`,
+			language: "markdown/gfm",
+		},
 		{
 			code: "[foo]: #",
 			options: [{ allowDefinitions: ["foo"] }],
@@ -63,10 +88,12 @@ ruleTester.run("no-empty-definitions", rule, {
 		},
 		{
 			code: "[^note]:",
+			language: "markdown/gfm",
 			options: [{ checkFootnoteDefinitions: false }],
 		},
 		{
 			code: "[^note]:",
+			language: "markdown/gfm",
 			options: [
 				{
 					checkFootnoteDefinitions: true,
@@ -124,18 +151,22 @@ ruleTester.run("no-empty-definitions", rule, {
 		},
 		{
 			code: "[^NOTE]:",
+			language: "markdown/gfm",
 			options: [{ allowFootnoteDefinitions: ["NOTE"] }],
 		},
 		{
 			code: "[^note]:",
+			language: "markdown/gfm",
 			options: [{ allowFootnoteDefinitions: ["NOTE"] }],
 		},
 		{
 			code: "[^NOTE]:",
+			language: "markdown/gfm",
 			options: [{ allowFootnoteDefinitions: ["note"] }],
 		},
 		{
 			code: "[^note]:",
+			language: "markdown/gfm",
 			options: [{ allowFootnoteDefinitions: ["   note   "] }],
 		},
 		// This test case is skipped when running on Bun
@@ -151,6 +182,7 @@ ruleTester.run("no-empty-definitions", rule, {
 					},
 					{
 						code: "[^Grüsse]:",
+						language: "markdown/gfm",
 						options: [{ allowFootnoteDefinitions: ["GRÜẞE"] }],
 					},
 				]
@@ -235,6 +267,7 @@ ruleTester.run("no-empty-definitions", rule, {
 		},
 		{
 			code: "[^note]:",
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "emptyFootnoteDefinition",
@@ -248,6 +281,7 @@ ruleTester.run("no-empty-definitions", rule, {
 		},
 		{
 			code: "[^Note]:",
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "emptyFootnoteDefinition",
@@ -261,6 +295,7 @@ ruleTester.run("no-empty-definitions", rule, {
 		},
 		{
 			code: "[^note]:   ",
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "emptyFootnoteDefinition",
@@ -274,6 +309,7 @@ ruleTester.run("no-empty-definitions", rule, {
 		},
 		{
 			code: "[^note]:\n",
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "emptyFootnoteDefinition",
@@ -287,6 +323,7 @@ ruleTester.run("no-empty-definitions", rule, {
 		},
 		{
 			code: "[^a]:\n[^b]:",
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "emptyFootnoteDefinition",
@@ -308,6 +345,7 @@ ruleTester.run("no-empty-definitions", rule, {
 		},
 		{
 			code: "[foo]: #\n[^note]:",
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "emptyDefinition",
@@ -329,6 +367,7 @@ ruleTester.run("no-empty-definitions", rule, {
 		},
 		{
 			code: "[foo]: #\n[^note]:",
+			language: "markdown/gfm",
 			options: [{ checkFootnoteDefinitions: false }],
 			errors: [
 				{
@@ -343,6 +382,7 @@ ruleTester.run("no-empty-definitions", rule, {
 		},
 		{
 			code: "[^foo]: <!-- comment -->",
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "emptyFootnoteDefinition",
@@ -358,6 +398,7 @@ ruleTester.run("no-empty-definitions", rule, {
 			code: dedent`
 			[^foo]: <!-- comment
 			    -->`,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "emptyFootnoteDefinition",
@@ -373,6 +414,7 @@ ruleTester.run("no-empty-definitions", rule, {
 			code: dedent`
 			[^foo]: <!-- comment -->
 			    <!-- another comment -->`,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "emptyFootnoteDefinition",
@@ -418,6 +460,7 @@ ruleTester.run("no-empty-definitions", rule, {
 		},
 		{
 			code: "[^foo]:",
+			language: "markdown/gfm",
 			options: [
 				{
 					allowDefinitions: ["foo"],
diff --git a/tests/rules/no-empty-images.test.js b/tests/rules/no-empty-images.test.js
index 16baa13c..abba9856 100644
--- a/tests/rules/no-empty-images.test.js
+++ b/tests/rules/no-empty-images.test.js
@@ -7,22 +7,14 @@
 // Imports
 //------------------------------------------------------------------------------
 
+import ruleTester from "./_utils/rule-tester.js";
 import rule from "../../src/rules/no-empty-images.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/commonmark",
-});
-
-ruleTester.run("no-empty-images", rule, {
+ruleTester("no-empty-images", rule, {
 	valid: ["![foo](bar)", "![foo](#bar)", "![foo](http://bar.com/image.png)"],
 	invalid: [
 		{
diff --git a/tests/rules/no-empty-links.test.js b/tests/rules/no-empty-links.test.js
index 75e950da..de0ab0b3 100644
--- a/tests/rules/no-empty-links.test.js
+++ b/tests/rules/no-empty-links.test.js
@@ -7,22 +7,14 @@
 // Imports
 //------------------------------------------------------------------------------
 
+import ruleTester from "./_utils/rule-tester.js";
 import rule from "../../src/rules/no-empty-links.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/commonmark",
-});
-
-ruleTester.run("no-empty-links", rule, {
+ruleTester("no-empty-links", rule, {
 	valid: ["[foo](bar)", "[foo](#bar)", "[foo](http://bar.com)"],
 	invalid: [
 		{
diff --git a/tests/rules/no-html.test.js b/tests/rules/no-html.test.js
index 9dcaa189..ecd1cf18 100644
--- a/tests/rules/no-html.test.js
+++ b/tests/rules/no-html.test.js
@@ -7,23 +7,15 @@
 // Imports
 //------------------------------------------------------------------------------
 
-import rule from "../../src/rules/no-html.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 import dedent from "dedent";
+import ruleTester from "./_utils/rule-tester.js";
+import rule from "../../src/rules/no-html.js";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/commonmark",
-});
-
-ruleTester.run("no-html", rule, {
+ruleTester("no-html", rule, {
 	valid: [
 		"Hello world!",
 		" 1 < 5",
diff --git a/tests/rules/no-invalid-label-refs.test.js b/tests/rules/no-invalid-label-refs.test.js
index 231f1490..5cf67a46 100644
--- a/tests/rules/no-invalid-label-refs.test.js
+++ b/tests/rules/no-invalid-label-refs.test.js
@@ -7,22 +7,14 @@
 // Imports
 //------------------------------------------------------------------------------
 
+import ruleTester from "./_utils/rule-tester.js";
 import rule from "../../src/rules/no-invalid-label-refs.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/commonmark",
-});
-
-ruleTester.run("no-invalid-label-refs", rule, {
+ruleTester("no-invalid-label-refs", rule, {
 	valid: [
 		"[*foo*]",
 		"[foo]\n\n[foo]: http://bar.com",
diff --git a/tests/rules/no-missing-atx-heading-space.test.js b/tests/rules/no-missing-atx-heading-space.test.js
index c7bfc273..6a6ed093 100644
--- a/tests/rules/no-missing-atx-heading-space.test.js
+++ b/tests/rules/no-missing-atx-heading-space.test.js
@@ -7,21 +7,9 @@
 // Imports
 //------------------------------------------------------------------------------
 
-import rule from "../../src/rules/no-missing-atx-heading-space.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 import dedent from "dedent";
-
-//------------------------------------------------------------------------------
-// Tests
-//------------------------------------------------------------------------------
-
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/gfm",
-});
+import ruleTester from "./_utils/rule-tester.js";
+import rule from "../../src/rules/no-missing-atx-heading-space.js";
 
 //------------------------------------------------------------------------------
 // Valid Test Cases
@@ -1170,7 +1158,7 @@ const invalidTests = [
 	},
 ];
 
-ruleTester.run("no-missing-atx-heading-space", rule, {
+ruleTester("no-missing-atx-heading-space", rule, {
 	valid: validHeadings,
 	invalid: invalidTests,
 });
diff --git a/tests/rules/no-missing-label-refs.test.js b/tests/rules/no-missing-label-refs.test.js
index 07ce97e2..61c275bc 100644
--- a/tests/rules/no-missing-label-refs.test.js
+++ b/tests/rules/no-missing-label-refs.test.js
@@ -7,23 +7,17 @@
 // Imports
 //------------------------------------------------------------------------------
 
-import rule from "../../src/rules/no-missing-label-refs.js";
-import markdown from "../../src/index.js";
-import { Linter, RuleTester } from "eslint";
 import dedent from "dedent";
+import { Linter } from "eslint";
+import ruleTester from "./_utils/rule-tester.js";
+import markdown from "../../src/index.js";
+import rule from "../../src/rules/no-missing-label-refs.js";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/commonmark",
-});
-
-ruleTester.run("no-missing-label-refs", rule, {
+ruleTester("no-missing-label-refs", rule, {
 	valid: [
 		"[*foo*]",
 		"[foo]\n\n[foo]: http://bar.com",
diff --git a/tests/rules/no-missing-link-fragments.test.js b/tests/rules/no-missing-link-fragments.test.js
index 573a814a..19e6a0a6 100644
--- a/tests/rules/no-missing-link-fragments.test.js
+++ b/tests/rules/no-missing-link-fragments.test.js
@@ -7,23 +7,17 @@
 // Imports
 //------------------------------------------------------------------------------
 
-import rule from "../../src/rules/no-missing-link-fragments.js";
-import markdown from "../../src/index.js";
-import { Linter, RuleTester } from "eslint";
 import dedent from "dedent";
+import { Linter } from "eslint";
+import ruleTester from "./_utils/rule-tester.js";
+import markdown from "../../src/index.js";
+import rule from "../../src/rules/no-missing-link-fragments.js";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/gfm",
-});
-
-ruleTester.run("no-missing-link-fragments", rule, {
+ruleTester("no-missing-link-fragments", rule, {
 	valid: [
 		// Basic heading match with `Link` node
 		dedent`
diff --git a/tests/rules/no-multiple-h1.test.js b/tests/rules/no-multiple-h1.test.js
index e86cdfd7..e45dcdf2 100644
--- a/tests/rules/no-multiple-h1.test.js
+++ b/tests/rules/no-multiple-h1.test.js
@@ -16,6 +16,8 @@ import dedent from "dedent";
 // Tests
 //------------------------------------------------------------------------------
 
+// TODO
+
 const ruleTester = new RuleTester({
 	plugins: {
 		markdown,
diff --git a/tests/rules/no-reference-like-urls.test.js b/tests/rules/no-reference-like-urls.test.js
index 3f6b6a33..2a9b8e29 100644
--- a/tests/rules/no-reference-like-urls.test.js
+++ b/tests/rules/no-reference-like-urls.test.js
@@ -16,6 +16,8 @@ import dedent from "dedent";
 // Tests
 //------------------------------------------------------------------------------
 
+// TODO
+
 const ruleTester = new RuleTester({
 	plugins: {
 		markdown,
diff --git a/tests/rules/no-reversed-media-syntax.test.js b/tests/rules/no-reversed-media-syntax.test.js
index ffbb14df..294a0de6 100644
--- a/tests/rules/no-reversed-media-syntax.test.js
+++ b/tests/rules/no-reversed-media-syntax.test.js
@@ -16,6 +16,8 @@ import dedent from "dedent";
 // Tests
 //------------------------------------------------------------------------------
 
+// TODO
+
 const ruleTester = new RuleTester({
 	plugins: {
 		markdown,
diff --git a/tests/rules/no-space-in-emphasis.test.js b/tests/rules/no-space-in-emphasis.test.js
index 72ef6730..f86167de 100644
--- a/tests/rules/no-space-in-emphasis.test.js
+++ b/tests/rules/no-space-in-emphasis.test.js
@@ -7,23 +7,15 @@
 // Imports
 //------------------------------------------------------------------------------
 
-import rule from "../../src/rules/no-space-in-emphasis.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 import dedent from "dedent";
+import ruleTester from "./_utils/rule-tester.js";
+import rule from "../../src/rules/no-space-in-emphasis.js";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/gfm",
-});
-
-ruleTester.run("no-space-in-emphasis", rule, {
+ruleTester("no-space-in-emphasis", rule, {
 	valid: [
 		"Line with *Normal emphasis*",
 		"Line with **Normal strong**",
@@ -31,9 +23,18 @@ ruleTester.run("no-space-in-emphasis", rule, {
 		"Line with _Normal emphasis_",
 		"Line with __Normal strong__",
 		"Line with ___Normal strong and emphasis___",
-		"Line with ~Normal strikethrough~",
-		"Line with ~~Normal strikethrough~~",
-		"Line with ~~*strikethrough and emphasis*~~",
+		{
+			code: "Line with ~Normal strikethrough~",
+			language: "markdown/gfm",
+		},
+		{
+			code: "Line with ~~Normal strikethrough~~",
+			language: "markdown/gfm",
+		},
+		{
+			code: "Line with ~~*strikethrough and emphasis*~~",
+			language: "markdown/gfm",
+		},
 		"But not with escaped\\* asterisks\\* \\_and \\_underscores.",
 		"But not with escaped\\~ tildes\\~ either.",
 		"* Emphasis* with left space is recognized as a list",
@@ -75,8 +76,14 @@ ruleTester.run("no-space-in-emphasis", rule, {
 		"Mixed `code*span` scenarios are *also* okay.",
 		"Mixed `code*span` scenarios are _also_ okay.",
 		"Mixed `code_span` scenarios are *also* okay.",
-		"Text ~ strikethrough ~ with spaces",
-		"Text ~~ strikethrough ~~ with spaces",
+		{
+			code: "Text ~ strikethrough ~ with spaces",
+			language: "markdown/gfm",
+		},
+		{
+			code: "Text ~~ strikethrough ~~ with spaces",
+			language: "markdown/gfm",
+		},
 		"[Link](under_score) followed by _underscore_",
 		"[Link](un_der_score) followed by _underscore_",
 		"[Link](un_der_sco_re) followed by _underscore_",
@@ -108,8 +115,14 @@ ruleTester.run("no-space-in-emphasis", rule, {
 		"text _underscore_*star* text _underscore_**star** text",
 		"text _underscore_**star** text _underscore_*star* text",
 		"text _underscore_**star** text _underscore_**star** text",
-		"text ~~strike~~*star* text ~strike~**star** text",
-		"text ~~strike~~_underscore_ text ~strike~__underscore__ text",
+		{
+			code: "text ~~strike~~*star* text ~strike~**star** text",
+			language: "markdown/gfm",
+		},
+		{
+			code: "text ~~strike~~_underscore_ text ~strike~__underscore__ text",
+			language: "markdown/gfm",
+		},
 		dedent`
 		> * List with *emphasis* in blockquote
 		>
@@ -182,35 +195,47 @@ ruleTester.run("no-space-in-emphasis", rule, {
 		**text**
 		***
 		`,
-		dedent`
-		| Table | Table |
-		| ----- | ----- |
-		| star  | x * y |
-		| under | x _ y |
-		`,
-		dedent`
-		| Table | Table |
-		| ----- | ----- |
-		| star  | x * y |
-		| star  | x * y |
-		| under | x _ y |
-		| under | x _ y |
-		`,
-		dedent`
-		| Table | Table                     |
-		| ----- | ------------------------- |
-		| star  | text *text* text          |
-		| under | text _text_ text          |
-		| strike| text ~text~ text          |
-		`,
-		dedent`
-		| Table | Table |
-		| ----- | ----- |
-		| x * y | x * y |
-		| x** y | x** y |
-		| x _ y | x _ y |
-		| x__ y | x__ y |
-		`,
+		{
+			code: dedent`
+			| Table | Table |
+			| ----- | ----- |
+			| star  | x * y |
+			| under | x _ y |
+			`,
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
+			| Table | Table |
+			| ----- | ----- |
+			| star  | x * y |
+			| star  | x * y |
+			| under | x _ y |
+			| under | x _ y |
+			`,
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
+			| Table | Table                     |
+			| ----- | ------------------------- |
+			| star  | text *text* text          |
+			| under | text _text_ text          |
+			| strike| text ~text~ text          |
+			`,
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
+			| Table | Table |
+			| ----- | ----- |
+			| x * y | x * y |
+			| x** y | x** y |
+			| x _ y | x _ y |
+			| x__ y | x__ y |
+			`,
+			language: "markdown/gfm",
+		},
 		dedent`
 		\`\`\`yaml /* autogenerated */
 		# YAML...
@@ -1248,6 +1273,7 @@ ruleTester.run("no-space-in-emphasis", rule, {
 			| under | text _text_ text          |
 			| under | text _text_ text          |
 			`,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "spaceInEmphasis",
@@ -1282,6 +1308,7 @@ ruleTester.run("no-space-in-emphasis", rule, {
 		{
 			code: "Broken ~ strikethrough ~ with spaces",
 			output: "Broken ~strikethrough~ with spaces",
+			language: "markdown/gfm",
 			options: [{ checkStrikethrough: true }],
 			errors: [
 				{
@@ -1303,6 +1330,7 @@ ruleTester.run("no-space-in-emphasis", rule, {
 		{
 			code: "Broken ~~ strikethrough ~~ with spaces",
 			output: "Broken ~~strikethrough~~ with spaces",
+			language: "markdown/gfm",
 			options: [{ checkStrikethrough: true }],
 			errors: [
 				{
@@ -1324,6 +1352,7 @@ ruleTester.run("no-space-in-emphasis", rule, {
 		{
 			code: "Mixed ~~ok strikethrough~~ and ~~ broken strikethrough ~~",
 			output: "Mixed ~~ok strikethrough~~ and ~~broken strikethrough~~",
+			language: "markdown/gfm",
 			options: [{ checkStrikethrough: true }],
 			errors: [
 				{
@@ -1345,6 +1374,7 @@ ruleTester.run("no-space-in-emphasis", rule, {
 		{
 			code: "Mixed ~ strikethrough ~ and * emphasis * with spaces",
 			output: "Mixed ~strikethrough~ and *emphasis* with spaces",
+			language: "markdown/gfm",
 			options: [{ checkStrikethrough: true }],
 			errors: [
 				{
@@ -1380,6 +1410,7 @@ ruleTester.run("no-space-in-emphasis", rule, {
 		{
 			code: "Mixed ~ok strikethrough~ and ~ broken strikethrough ~",
 			output: "Mixed ~ok strikethrough~ and ~broken strikethrough~",
+			language: "markdown/gfm",
 			options: [{ checkStrikethrough: true }],
 			errors: [
 				{
@@ -1401,6 +1432,7 @@ ruleTester.run("no-space-in-emphasis", rule, {
 		{
 			code: "# Broken ~ strikethrough ~ with spaces",
 			output: "# Broken ~strikethrough~ with spaces",
+			language: "markdown/gfm",
 			options: [{ checkStrikethrough: true }],
 			errors: [
 				{
@@ -1432,6 +1464,7 @@ ruleTester.run("no-space-in-emphasis", rule, {
 			| strike | text ~text~ text          |
 			| strike | text ~text~ text          |
 			`,
+			language: "markdown/gfm",
 			options: [{ checkStrikethrough: true }],
 			errors: [
 				{
diff --git a/tests/rules/no-unused-definitions.test.js b/tests/rules/no-unused-definitions.test.js
index 45669b12..cfe53195 100644
--- a/tests/rules/no-unused-definitions.test.js
+++ b/tests/rules/no-unused-definitions.test.js
@@ -7,22 +7,14 @@
 // Imports
 //------------------------------------------------------------------------------
 
+import ruleTester from "./_utils/rule-tester.js";
 import rule from "../../src/rules/no-unused-definitions.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/gfm",
-});
-
-ruleTester.run("no-unused-definitions", rule, {
+ruleTester("no-unused-definitions", rule, {
 	valid: [
 		"",
 		"   ",
@@ -68,34 +60,46 @@ ruleTester.run("no-unused-definitions", rule, {
 
 [venus]: https://example.com/venus.jpg
 `, // Image - shortcut
-		`
+		{
+			code: `
 Mercury[^mercury]
 
 [^mercury]: Hello, Mercury!
 `,
-		`
+			language: "markdown/gfm",
+		},
+		{
+			code: `
 Mercury[^mercury]
 
 [^mercury]: Hello, Mercury!
 [^Mercury]: Hello, Venus!
 `, // case insensitive
-		`
+			language: "markdown/gfm",
+		},
+		{
+			code: `
 Mercury[^mercury]
 
 [^mercury]: https://example.com/mercury/
 [    ^mercury       ]: https://example.com/venus/
 `, // with extra spaces
+			language: "markdown/gfm",
+		},
 		`
 [//]: # (This is a comment 1)
 [//]: <> (This is a comment 2)
 `,
-		`
+		{
+			code: `
 [Alpha][alpha] and [Alpha][^alpha]
 
 [alpha]: bravo
 
 [^alpha]: bravo
 `,
+			language: "markdown/gfm",
+		},
 		{
 			code: `
 [mercury]: https://example.com/mercury/
@@ -113,6 +117,7 @@ Mercury[^mercury]
 [^mercury]: Hello, Mercury!
 [^mercury]: Hello, Venus!
 `,
+			language: "markdown/gfm",
 			options: [
 				{
 					allowFootnoteDefinitions: ["mercury"],
@@ -169,6 +174,7 @@ Mercury[^mercury]
 		},
 		{
 			code: "[^MERCURY]: Hello, Mercury!",
+			language: "markdown/gfm",
 			options: [
 				{
 					allowFootnoteDefinitions: ["MERCURY"],
@@ -177,6 +183,7 @@ Mercury[^mercury]
 		},
 		{
 			code: "[^mercury]: Hello, Mercury!",
+			language: "markdown/gfm",
 			options: [
 				{
 					allowFootnoteDefinitions: ["MERCURY"],
@@ -185,6 +192,7 @@ Mercury[^mercury]
 		},
 		{
 			code: "[^MERCURY]: Hello, Mercury!",
+			language: "markdown/gfm",
 			options: [
 				{
 					allowFootnoteDefinitions: ["mercury"],
@@ -193,6 +201,7 @@ Mercury[^mercury]
 		},
 		{
 			code: "[^mercury]: Hello, Mercury!",
+			language: "markdown/gfm",
 			options: [
 				{
 					allowFootnoteDefinitions: ["   mercury   "],
@@ -201,6 +210,7 @@ Mercury[^mercury]
 		},
 		{
 			code: "[^mercury]: Hello, Mercury!",
+			language: "markdown/gfm",
 			options: [
 				{
 					checkFootnoteDefinitions: false,
@@ -209,6 +219,7 @@ Mercury[^mercury]
 		},
 		{
 			code: "[^mercury]: Hello, Mercury!",
+			language: "markdown/gfm",
 			options: [
 				{
 					checkFootnoteDefinitions: true,
@@ -229,6 +240,7 @@ Mercury[^mercury]
 					},
 					{
 						code: "[^Grüsse]: Grüsse",
+						language: "markdown/gfm",
 						options: [
 							{
 								allowFootnoteDefinitions: ["GRÜẞE"],
@@ -349,6 +361,7 @@ Mercury[^mercury]
 			code: `
 [^mercury]: Hello, Mercury!
 `,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "unusedFootnoteDefinition",
@@ -365,6 +378,7 @@ Mercury[^mercury]
 			code: `
 [^Mercury]: Hello, Mercury!
 `,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "unusedFootnoteDefinition",
@@ -383,6 +397,7 @@ Mercury[^mercury]
 [^mercury]: Hello, Venus!
 [^mercury]: Hello, Earth!
 `,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "unusedFootnoteDefinition",
@@ -415,6 +430,7 @@ Mercury[^mercury]
 			code: `
 [^mercury]: Hello, Mercury!
 `,
+			language: "markdown/gfm",
 			options: [
 				{
 					allowDefinitions: ["mercury"],
@@ -438,6 +454,7 @@ Mercury[^mercury]
 			code: `
 [^mercury]: Hello, Mercury!
 `,
+			language: "markdown/gfm",
 			options: [
 				{
 					checkFootnoteDefinitions: true,
diff --git a/tests/rules/require-alt-text.test.js b/tests/rules/require-alt-text.test.js
index 22890ff8..b7c990ac 100644
--- a/tests/rules/require-alt-text.test.js
+++ b/tests/rules/require-alt-text.test.js
@@ -16,6 +16,8 @@ import dedent from "dedent";
 // Tests
 //------------------------------------------------------------------------------
 
+// TODO
+
 const ruleTester = new RuleTester({
 	plugins: {
 		markdown,
diff --git a/tests/rules/table-column-count.test.js b/tests/rules/table-column-count.test.js
index c6fd71c2..51369ee2 100644
--- a/tests/rules/table-column-count.test.js
+++ b/tests/rules/table-column-count.test.js
@@ -7,53 +7,64 @@
 // Imports
 //------------------------------------------------------------------------------
 
-import rule from "../../src/rules/table-column-count.js";
-import markdown from "../../src/index.js";
-import { RuleTester } from "eslint";
 import dedent from "dedent";
+import ruleTester from "./_utils/rule-tester.js";
+import rule from "../../src/rules/table-column-count.js";
 
 //------------------------------------------------------------------------------
 // Tests
 //------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({
-	plugins: {
-		markdown,
-	},
-	language: "markdown/gfm",
-});
-
-ruleTester.run("table-column-count", rule, {
+ruleTester("table-column-count", rule, {
 	valid: [
-		dedent`
+		{
+			code: dedent`
             | Header | Header |
             | ------ | ------ |
             | Cell   | Cell   |
             | Cell   | Cell   |
         `,
-		dedent`
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
             | Header | Header | Header |
             | ------ | ------ | ------ |
             | Cell   | Cell   |
             | Cell   |        |
         `,
-		dedent`
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
             | A | B |
             |---|---|
             |   |   |
             | C |   |
         `,
-		`Just some text. | not a table |`,
-		dedent`
+			language: "markdown/gfm",
+		},
+		{
+			code: `Just some text. | not a table |`,
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
             | Header | Header |
             | ------ | ------ | ----- |
             | Cell   | Cell   |
         `,
-		dedent`
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
             | Header | Header |
             | ------ | ------ |
         `,
-		dedent`
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
             Some text before.
 
             | H1 | H2 |
@@ -62,48 +73,67 @@ ruleTester.run("table-column-count", rule, {
 
             Some text after.
         `,
-		dedent`
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
             | Valid | Table |
             | ----- | ----- |
             | Row   | Here  |
         `,
-		dedent`
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
 			| abc | defghi |
 			:-: | -----------:
 			bar | baz
 		`,
-		dedent`
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
             | f|oo  |
             | ------ |
             | b \`|\` az |
             | b **|** im |
         `,
-		dedent`
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
 			| abc | def |
 			| --- | --- |
 			| bar | baz |
 			> bar
 		`,
-		dedent`
+			language: "markdown/gfm",
+		},
+		{
+			code: dedent`
 			| abc | def |
 			| --- | --- |
 		`,
+			language: "markdown/gfm",
+		},
 		{
 			code: dedent`
             | Header | Header |
             | ------ | ------ |
-            | Cell   | Cell   |
-            | Cell   | Cell   |
+			| Cell   | Cell   |
+			| Cell   | Cell   |
         	`,
+			language: "markdown/gfm",
 			options: [{ checkMissingCells: true }],
 		},
 		{
 			code: dedent`
             | Header | Header |
             | ------ | ------ |
-            | Cell   |        |
-            | Cell   | Cell   |
+			| Cell   |        |
+			| Cell   | Cell   |
         	`,
+			language: "markdown/gfm",
 			options: [{ checkMissingCells: true }],
 		},
 	],
@@ -115,6 +145,7 @@ ruleTester.run("table-column-count", rule, {
                 | ----- | ----- |
                 | R1C1  | R1C2  | R2C3  |
             `,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "extraCells",
@@ -132,6 +163,7 @@ ruleTester.run("table-column-count", rule, {
                 | ----- | ----- |
                 | R1C1  | R1C2  | R2C3  | R3C4 |
             `,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "extraCells",
@@ -149,6 +181,7 @@ ruleTester.run("table-column-count", rule, {
                 | - |
                 | 1 | 2 |
             `,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "extraCells",
@@ -171,6 +204,7 @@ ruleTester.run("table-column-count", rule, {
 
                 Some concluding text.
             `,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "extraCells",
@@ -189,6 +223,7 @@ ruleTester.run("table-column-count", rule, {
 				bar | baz
 				bar | baz | bad
             `,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "extraCells",
@@ -207,6 +242,7 @@ ruleTester.run("table-column-count", rule, {
 					| bar | baz | Extra |
 					> This is a blockquote after
 				`,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "extraCells",
@@ -225,6 +261,7 @@ ruleTester.run("table-column-count", rule, {
 				| bar | baz | Extra1 |
 				| bar | baz | Extra2 |
 			`,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "extraCells",
@@ -252,6 +289,7 @@ ruleTester.run("table-column-count", rule, {
 		    | bar | baz |
 			| bar | baz | Extra2 |
 		`,
+			language: "markdown/gfm",
 			errors: [
 				{
 					messageId: "extraCells",
@@ -277,6 +315,7 @@ ruleTester.run("table-column-count", rule, {
                 | ------ | ------ | ------ |
                 | Cell   | Cell   |
             `,
+			language: "markdown/gfm",
 			options: [{ checkMissingCells: true }],
 			errors: [
 				{
@@ -296,6 +335,7 @@ ruleTester.run("table-column-count", rule, {
                 | Cell  |       | Cell  |
                 | Cell  | Cell  |
             `,
+			language: "markdown/gfm",
 			options: [{ checkMissingCells: true }],
 			errors: [
 				{
@@ -316,6 +356,7 @@ ruleTester.run("table-column-count", rule, {
                 | Cell  | Cell  |
                 | Cell  | Cell  | Cell  |
             `,
+			language: "markdown/gfm",
 			options: [{ checkMissingCells: true }],
 			errors: [
 				{
@@ -344,6 +385,7 @@ ruleTester.run("table-column-count", rule, {
                 | Cell  |
                 | Cell  | Cell  |
             `,
+			language: "markdown/gfm",
 			options: [{ checkMissingCells: true }],
 			errors: [
 				{
@@ -372,6 +414,7 @@ ruleTester.run("table-column-count", rule, {
                 | Cell  |
                 | Cell  | Cell   |
             `,
+			language: "markdown/gfm",
 			options: [{ checkMissingCells: true }],
 			errors: [
 				{
@@ -400,6 +443,7 @@ ruleTester.run("table-column-count", rule, {
                 | Cell  | Cell   | Cell   | Cell   |
                 | Cell  |
             `,
+			language: "markdown/gfm",
 			options: [{ checkMissingCells: true }],
 			errors: [
 				{