feat(rules): make body-max-line-length ignore lines with URLs

Whilst the `body-max-line-length` is almost always desirable, there
is one fairly frequent scenario in which it gets in the way: when
lines contain URLs exceeding the maximum line length.

In this case, the URL cannot be split across lines without breaking
it, and minifying it results in obfuscation and a dependency on a
third-party service, both of which are undesirable.

So make an exception in this rule for any line which contains a URL.
Allow other content on the same line, in order to support use of
various rich-text formats such as Markdown, which are often used
in order to render links in more elegant ways.

Author: aspiers

@commitlint/ensure/src/max-line-length.ts

@@ -1,5 +1,13 @@
 import ensure from "./max-length.js";
 
+// Allow an exception for long lines which contain URLs.
+//
+// This is overly lenient, in order to avoid costly regexps which
+// have to worry about all the many edge cases of valid URLs.
+const URL_REGEX = /\bhttps?:\/\/\S+\.\S+/;
+
 export default (value: string, max: number): boolean =>
 	typeof value === "string" &&
-	value.split(/\r?\n/).every((line) => ensure(line, max));
+	value
+		.split(/\r?\n/)
+		.every((line) => URL_REGEX.test(line) || ensure(line, max));

@commitlint/rules/src/body-max-line-length.test.ts

@@ -1,9 +1,11 @@
 import { test, expect } from "vitest";
 import parse from "@commitlint/parse";
+import type { Commit } from "conventional-commits-parser";
 import { bodyMaxLineLength } from "./body-max-line-length.js";
 
 const short = "a";
 const long = "ab";
+const url = "https://example.com/URL/with/a/very/long/path";
 
 const value = short.length;
 
@@ -13,16 +15,30 @@ const messages = {
 	long: `test: subject\n${long}`,
 	shortMultipleLines: `test:subject\n${short}\n${short}\n${short}`,
 	longMultipleLines: `test:subject\n${short}\n${long}\n${short}`,
-};
+	urlStandalone: `test:subject\n${short}\n${url}\n${short}`,
+	urlMarkdownLinkInline: `test:subject
+
+This is a [link](${url}).`,
+	urlMarkdownLinkInList: `test:subject
+
+Link in a list:
+
+- ${url}`,
+	urlMarkdownLinkInFooter: `test:subject
+
+Finally, [link][] via footer.
 
-const parsed = {
-	empty: parse(messages.empty),
-	short: parse(messages.short),
-	long: parse(messages.long),
-	shortMultipleLines: parse(messages.shortMultipleLines),
-	longMultipleLines: parse(messages.longMultipleLines),
+[link]: ${url}`,
 };
 
+const parsed = Object.entries(messages).reduce(
+	(_parsed, [key, message]) =>
+		Object.assign(_parsed, {
+			[key]: parse(message),
+		}),
+	{} as Record<keyof typeof messages, Promise<Commit>>,
+);
+
 test("with empty should succeed", async () => {
 	const [actual] = bodyMaxLineLength(await parsed.empty, undefined, value);
 	const expected = true;
@@ -45,7 +61,7 @@ test("with short with multiple lines should succeed", async () => {
 	const [actual] = bodyMaxLineLength(
 		await parsed.shortMultipleLines,
 		undefined,
-		value
+		value,
 	);
 	const expected = true;
 	expect(actual).toEqual(expected);
@@ -55,8 +71,28 @@ test("with long with multiple lines should fail", async () => {
 	const [actual] = bodyMaxLineLength(
 		await parsed.longMultipleLines,
 		undefined,
-		value
+		value,
 	);
 	const expected = false;
 	expect(actual).toEqual(expected);
 });
+
+test("with multiple lines and standalone URL should succeed", async () => {
+	const [actual] = bodyMaxLineLength(
+		await parsed.urlStandalone,
+		undefined,
+		value,
+	);
+	const expected = true;
+	expect(actual).toEqual(expected);
+});
+
+test("with multiple lines and URL in inline Markdown link should succeed", async () => {
+	const [actual] = bodyMaxLineLength(
+		await parsed.urlMarkdownLinkInline,
+		undefined,
+		30,
+	);
+	const expected = true;
+	expect(actual).toEqual(expected);
+});

docs/reference/rules.md

@@ -32,7 +32,7 @@
 
 ## body-max-line-length
 
-- **condition**: `body` lines has `value` or less characters
+- **condition**: `body` lines have `value` or less characters, or contain a URL
 - **rule**: `always`
 - **value**
 
@@ -97,7 +97,7 @@
 
 ## footer-max-line-length
 
-- **condition**: `footer` lines has `value` or less characters
+- **condition**: `footer` lines have `value` or less characters
 - **rule**: `always`
 - **value**