Disallow unknown custom media queries (#4)

Resolves #3

CHANGELOG.md

@@ -7,6 +7,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com), and 
 
 ## [Unreleased]
 
+### Changed
+
+- The custom media queries should now be defined within the same source.
+
 ### Fixed
 
 - Zero length value no longer requires no units in all cases.

stylelint.config.js

@@ -71,6 +71,7 @@ export default {
 		"no-invalid-double-slash-comments": true,
 		"no-invalid-position-at-import-rule": true,
 		"no-irregular-whitespace": true,
+		"no-unknown-custom-media": true,
 		"number-max-precision": [
 			3,
 			{

test/no-unknown-custom-media.js

@@ -0,0 +1,43 @@
+import { testRule } from "../utils/testRule.js"
+
+let rule = `no-unknown-custom-media`
+
+let code = `
+@custom-media --any-valid (width >= 40rem);
+
+@media (--any-valid), (height < 40rem) {}
+
+@media (--another-valid) {}
+
+@custom-media --another-valid (width >= 60rem);
+
+@media (--invalid) {}
+
+@media (--invalid), (height < 40rem) {}
+`
+
+testRule({
+	description: `Custom media queries should be known`,
+	rule,
+	code,
+	expectedWarnings: [
+		{
+			line: 10,
+			column: 9,
+			endLine: 10,
+			endColumn: 18,
+			rule,
+			severity: `error`,
+			text: `Unexpected unknown custom media "--invalid" (${rule})`,
+		},
+		{
+			line: 12,
+			column: 9,
+			endLine: 12,
+			endColumn: 18,
+			rule,
+			severity: `error`,
+			text: `Unexpected unknown custom media "--invalid" (${rule})`,
+		},
+	],
+})