feat(rules): new rule `script-element`

docs/rules/__tests__/__snapshots__/script-element.md.spec.ts.snap

+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`docs/rules/script-element.md inline validation: correct 1`] = `Array []`;
+
+exports[`docs/rules/script-element.md inline validation: incorrect 1`] = `
+Array [
+  Object {
+    "errorCount": 1,
+    "filePath": "inline",
+    "messages": Array [
+      Object {
+        "column": 26,
+        "context": undefined,
+        "line": 1,
+        "message": "End tag for <script> must not be omitted",
+        "offset": 25,
+        "ruleId": "script-element",
+        "selector": "script",
+        "severity": 2,
+        "size": 2,
+      },
+    ],
+    "source": "<script src=\\"myscript.js\\"/>",
+    "warningCount": 0,
+  },
+]
+`;

docs/rules/__tests__/script-element.md.spec.ts

+import HtmlValidate from "../../../src/htmlvalidate";
+
+const markup: { [key: string]: string } = {};
+markup["incorrect"] = `<script src="myscript.js"/>`;
+markup["correct"] = `<script src="myscript.js"></script>`;
+
+describe("docs/rules/script-element.md", () => {
+	it("inline validation: incorrect", () => {
+		const htmlvalidate = new HtmlValidate({"rules":{"script-element":"error"}});
+		const report = htmlvalidate.validateString(markup["incorrect"]);
+		expect(report.results).toMatchSnapshot();
+	});
+	it("inline validation: correct", () => {
+		const htmlvalidate = new HtmlValidate({"rules":{"script-element":"error"}});
+		const report = htmlvalidate.validateString(markup["correct"]);
+		expect(report.results).toMatchSnapshot();
+	});
+});

docs/rules/script-element.md

+---
+docType: rule
+name: script-element
+category: content-model
+summary: Require end tag for `<script>`
+---
+
+# Require end tag for `<script>` element (`script-element`)
+
+For legacy reasons the `<script>` element must include a `</script>` end tag even when using the `src` attribute.
+
+## Rule details
+
+Examples of **incorrect** code for this rule:
+
+<validate name="incorrect" rules="script-element">
+    <script src="myscript.js"/>
+</validate>
+
+Examples of **correct** code for this rule:
+
+<validate name="correct" rules="script-element">
+    <script src="myscript.js"></script>
+</validate>

elements/__snapshots__/html5.spec.ts.snap

@@ -4838,7 +4838,7 @@ exports[`HTML elements <samp> valid markup 1`] = `Array []`;
 exports[`HTML elements <script> invalid markup 1`] = `
 Array [
   Object {
-    "errorCount": 3,
+    "errorCount": 4,
     "filePath": "test-files/elements/script-invalid.html",
     "messages": Array [
       Object {
@@ -4881,6 +4881,17 @@ Array [
         "severity": 2,
         "size": 2,
       },
+      Object {
+        "column": 8,
+        "context": undefined,
+        "line": 8,
+        "message": "End tag for <script> must not be omitted",
+        "offset": 330,
+        "ruleId": "script-element",
+        "selector": "script:nth-child(3)",
+        "severity": 2,
+        "size": 2,
+      },
     ],
     "source": "<!-- src attribute cannot be empty -->
 <script src=\\"\\"></script>

src/config/recommended.ts

@@ -34,6 +34,7 @@ module.exports = {
 		"prefer-button": "error",
 		"prefer-native-element": "error",
 		"prefer-tbody": "error",
+		"script-element": "error",
 		"svg-focusable": "error",
 		"unrecognized-char-ref": "error",
 		void: "off",

src/engine/engine.spec.ts

@@ -76,7 +76,7 @@ describe("Engine", () => {
 		config = Config.fromObject({
 			extends: ["html-validate:recommended"],
 			rules: {
-				deprecated: "off"
+				deprecated: "off",
 			},
 		});
 		config.init();

src/rules/__snapshots__/script-element.spec.ts.snap

+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`rule script-element should contain documentation 1`] = `
+Object {
+  "description": "The end tag for \`<script>\` is a hard requirement and must never be omitted even when using the \`src\` attribute.",
+  "url": "https://html-validate.org/rules/script-element.html",
+}
+`;

src/rules/script-element.spec.ts

+import HtmlValidate from "../htmlvalidate";
+import "../matchers";
+
+describe("rule script-element", () => {
+	let htmlvalidate: HtmlValidate;
+
+	beforeAll(() => {
+		htmlvalidate = new HtmlValidate({
+			rules: { "script-element": "error" },
+		});
+	});
+
+	it("should not report when script element has end tag", () => {
+		const report = htmlvalidate.validateString("<script></script>");
+		expect(report).toBeValid();
+	});
+
+	it("should report when script element is self-closed", () => {
+		const report = htmlvalidate.validateString("<script/>");
+		expect(report).toHaveError(
+			"script-element",
+			"End tag for <script> must not be omitted"
+		);
+	});
+
+	it("should handle stray end tag", () => {
+		const report = htmlvalidate.validateString("</script>");
+		expect(report).toBeValid();
+	});
+
+	it("should handle missing end tag", () => {
+		const report = htmlvalidate.validateString("<script>");
+		expect(report).toBeValid();
+	});
+
+	it("should contain documentation", () => {
+		expect(
+			htmlvalidate.getRuleDocumentation("script-element")
+		).toMatchSnapshot();
+	});
+});

src/rules/script-element.ts

+import { NodeClosed } from "../dom";
+import { TagCloseEvent } from "../event";
+import { Rule, RuleDocumentation, ruleDocumentationUrl } from "../rule";
+
+class ScriptElement extends Rule {
+	public documentation(): RuleDocumentation {
+		return {
+			description:
+				"The end tag for `<script>` is a hard requirement and must never be omitted even when using the `src` attribute.",
+			url: ruleDocumentationUrl(__filename),
+		};
+	}
+
+	public setup(): void {
+		this.on("tag:close", (event: TagCloseEvent) => {
+			const node = event.target; // The current element being closed.
+
+			if (!node || node.tagName !== "script") {
+				return;
+			}
+
+			if (node.closed !== NodeClosed.EndTag) {
+				this.report(node, `End tag for <${node.tagName}> must not be omitted`);
+			}
+		});
+	}
+}
+
+module.exports = ScriptElement;