Simplify no-unclosed-tag rule

packages/lit-analyzer/src/lib/analyze/parse/document/text-document/html-document/parse-html-node/parse-html-node.ts

@@ -49,7 +49,6 @@ export function parseHtmlNode(p5Node: IP5TagNode, parent: HtmlNode | undefined,
 
 	const htmlNodeBase: IHtmlNodeBase = {
 		tagName: p5Node.tagName.toLowerCase(),
-		selfClosed: isSelfClosed(p5Node, context),
 		attributes: [],
 		location: makeHtmlNodeLocation(p5Node, context),
 		children: [],
@@ -69,17 +68,6 @@ export function parseHtmlNode(p5Node: IP5TagNode, parent: HtmlNode | undefined,
 	return htmlNode;
 }
 
-/**
- * Returns if this node is self-closed.
- * @param p5Node
- * @param context
- */
-function isSelfClosed(p5Node: IP5TagNode, context: ParseHtmlContext) {
-	const isEmpty = p5Node.childNodes == null || p5Node.childNodes.length === 0;
-	const isSelfClosed = getSourceLocation(p5Node)!.startTag.endOffset === getSourceLocation(p5Node)!.endOffset;
-	return isEmpty && isSelfClosed;
-}
-
 /**
  * Creates source code location from a p5Node.
  * @param p5Node

packages/lit-analyzer/src/lib/analyze/types/html-node/html-node-types.ts

@@ -20,7 +20,6 @@ export interface IHtmlNodeBase {
 	attributes: HtmlNodeAttr[];
 	parent?: HtmlNode;
 	children: HtmlNode[];
-	selfClosed: boolean;
 	document: HtmlDocument;
 }
 

packages/lit-analyzer/src/lib/rules/no-unclosed-tag.ts

@@ -2,6 +2,29 @@ import { RuleModule } from "../analyze/types/rule/rule-module.js";
 import { isCustomElementTagName } from "../analyze/util/is-valid-name.js";
 import { rangeFromHtmlNode } from "../analyze/util/range-util.js";
 
+// List taken from https://html.spec.whatwg.org/multipage/syntax.html#void-elements
+// and parse5 list of void elements: https://github.com/inikulin/parse5/blob/86f09edd5a6840ab2269680b0eef2945e78c38fd/packages/parse5/lib/serializer/index.ts#L7-L26
+const VOID_ELEMENTS = new Set([
+	"area",
+	"base",
+	"basefont",
+	"bgsound",
+	"br",
+	"col",
+	"embed",
+	"frame",
+	"hr",
+	"img",
+	"input",
+	"keygen",
+	"link",
+	"meta",
+	"param",
+	"source",
+	"track",
+	"wbr"
+]);
+
 /**
  * This rule validates that all tags are closed properly.
  */
@@ -11,18 +34,18 @@ const rule: RuleModule = {
 		priority: "low"
 	},
 	visitHtmlNode(htmlNode, context) {
-		if (!htmlNode.selfClosed && htmlNode.location.endTag == null) {
-			// Report specifically that a custom element cannot be self closing
-			//   if the user is trying to close a custom element.
-			const isCustomElement = isCustomElementTagName(htmlNode.tagName);
-
-			context.report({
-				location: rangeFromHtmlNode(htmlNode),
-				message: `This tag isn't closed.${isCustomElement ? " Custom elements cannot be self closing." : ""}`
-			});
+		if (VOID_ELEMENTS.has(htmlNode.tagName.toLowerCase()) || htmlNode.location.endTag != null) {
+			return;
 		}
 
-		return;
+		// Report specifically that a custom element cannot be self closing
+		//   if the user is trying to close a custom element.
+		const isCustomElement = isCustomElementTagName(htmlNode.tagName);
+
+		context.report({
+			location: rangeFromHtmlNode(htmlNode),
+			message: `This tag isn't closed.${isCustomElement ? " Custom elements cannot be self closing." : ""}`
+		});
 	}
 };
 

packages/lit-analyzer/src/test/rules/no-unclosed-tag.ts

@@ -7,7 +7,41 @@ tsTest("Report unclosed tags", t => {
 	hasDiagnostic(t, diagnostics, "no-unclosed-tag");
 });
 
-tsTest("Don't report self closed tags", t => {
+tsTest("Don't report void elements", t => {
+	const { diagnostics } = getDiagnostics("html`<img>`", { rules: { "no-unclosed-tag": true } });
+	hasNoDiagnostics(t, diagnostics);
+});
+
+tsTest("Don't report void elements with self closing syntax", t => {
 	const { diagnostics } = getDiagnostics("html`<img />`", { rules: { "no-unclosed-tag": true } });
 	hasNoDiagnostics(t, diagnostics);
 });
+
+// The `<p>` tag will be closed automatically if immediately followed by a lot of other elements,
+// including `<div>`.
+// Ref: https://html.spec.whatwg.org/multipage/grouping-content.html#the-p-element
+tsTest("Report unclosed 'p' tag that was implicitly closed via tag omission", t => {
+	const { diagnostics } = getDiagnostics("html`<p><div></div></p>`", { rules: { "no-unclosed-tag": true } });
+	hasDiagnostic(t, diagnostics, "no-unclosed-tag");
+});
+
+tsTest("Report unclosed 'p' tag that is implicitly closed via tag omission containing text content", t => {
+	const { diagnostics } = getDiagnostics("html`<p>Unclosed Content<div></div></p>`", { rules: { "no-unclosed-tag": true } });
+	hasDiagnostic(t, diagnostics, "no-unclosed-tag");
+});
+
+// Self-closing tags do not exist in HTML. They are only valid in SVG and MathML.
+tsTest("Report non-void element using self closing syntax", t => {
+	const { diagnostics } = getDiagnostics("html`<p /><div></div>`", { rules: { "no-unclosed-tag": true } });
+	hasDiagnostic(t, diagnostics, "no-unclosed-tag");
+});
+
+tsTest("Report self closing 'p' tag containing text content", t => {
+	const { diagnostics } = getDiagnostics("html`<p />Unclosed Content<div></div>`", { rules: { "no-unclosed-tag": true } });
+	hasDiagnostic(t, diagnostics, "no-unclosed-tag");
+});
+
+tsTest("Don't report explicit closing 'p' tag containing text content", t => {
+	const { diagnostics } = getDiagnostics("html`<p>Unclosed Content</p><div></div>`", { rules: { "no-unclosed-tag": true } });
+	hasNoDiagnostics(t, diagnostics);
+});