Add support for scoped shareable configs (#480)

Author: tjrgg

lib/options-manager.js

@@ -345,6 +345,10 @@ const buildExtendsConfig = options => config => {
 				return name;
 			}
 
+			if (name.startsWith('@')) {
+				return name;
+			}
+
 			if (!name.includes('eslint-config-')) {
 				name = `eslint-config-${name}`;
 			}

test/options-manager.js

@@ -423,13 +423,17 @@ test('buildConfig: extends', t => {
 	const config = manager.buildConfig({extends: [
 		'plugin:foo/bar',
 		'eslint-config-foo-bar',
-		'foo-bar-two'
+		'foo-bar-two',
+		'@foobar',
+		'@foobar/eslint-config'
 	]});
 
-	t.deepEqual(config.baseConfig.extends.slice(-3), [
+	t.deepEqual(config.baseConfig.extends.slice(-5), [
 		'plugin:foo/bar',
 		'cwd/eslint-config-foo-bar',
-		'cwd/eslint-config-foo-bar-two'
+		'cwd/eslint-config-foo-bar-two',
+		'@foobar',
+		'@foobar/eslint-config'
 	]);
 });