Add test for WP5.5 path regex and update pattern for proper matching

Author: kadamwhite

lib/util/named-group-regexp.js

@@ -14,7 +14,7 @@ const pattern = [
 	'[>\']',
 	// Get everything up to the end of the capture group: this is the RegExp used
 	// when matching URLs to this route, which we can use for validation purposes.
-	'([^\\)]*(\\))?)\\??',
+	'([^\\)]*(\\))?\\??)',
 	// Capture group end
 	'\\)',
 ].join( '' );

tests/unit/lib/util/named-group-regexp.js

@@ -46,4 +46,12 @@ describe( 'named PCRE group RegExp', () => {
 		expect( result[ 2 ] ).toBe( '' );
 	} );
 
+	it( 'correctly handles WP 5.5 plugins routes', () => {
+		const path = '(?P<plugin>[^.\\/]+(?:\\/[^.\\/]+)?)';
+		const result = path.match( namedGroupRE );
+		expect( result ).not.toBeNull();
+		expect( result[ 1 ] ).toBe( 'plugin' );
+		expect( result[ 2 ] ).toBe( '[^.\\/]+(?:\\/[^.\\/]+)?' );
+	} );
+
 } );