Added a test for not mangling the entry point

test/function/does-not-mangle-entry-point/_config.js

@@ -0,0 +1,26 @@
+var path = require( 'path' );
+var fs = require( 'fs' );
+var assert = require( 'assert' );
+
+var modules = {
+	'x\\y': 'export default 42;',
+	'x/y': 'export default 24;'
+};
+
+module.exports = {
+	description: 'does not mangle entry point',
+	options: {
+		entry: 'x\\y',
+		plugins: [{
+			resolveId: function ( importee ) {
+				return importee;
+			},
+			load: function ( moduleId ) {
+				return modules[ moduleId ];
+			}
+		}]
+	},
+	exports: function ( exports ) {
+		assert.equal( exports, 42 );
+	}
+};