fix helper renaming (#22)

packages/rollup-plugin-babel/src/index.js

@@ -86,7 +86,7 @@ export default function babel ( options ) {
 
 			return buildExternalHelpers( helpers, 'var' )
 				.replace( /var babelHelpers.+\n/, '' )
-				.replace( /babelHelpers\.(.+) = function/g, 'function babelHelpers_$1' )
+				.replace( /babelHelpers\.(.+) = function(?: \w+)?/g, 'function babelHelpers_$1' )
 				.replace( /babelHelpers\.(.+) = /g, 'var babelHelpers_$1 = ' )
 				.replace( 'babelHelpers;', '' ) // not sure where this comes from...
 				.trim() + '\n';

packages/rollup-plugin-babel/test/samples/named-function-helper/_config.js

@@ -0,0 +1,4 @@
+module.exports = {
+	solo: true,
+	description: 'correctly renames helpers'
+};

packages/rollup-plugin-babel/test/samples/named-function-helper/main.js

@@ -0,0 +1,11 @@
+class Bar {
+	baz () {
+		alert( 'baz' );
+	}
+}
+
+export class Foo extends Bar {
+	baz () {
+		super.baz();
+	}
+}

packages/rollup-plugin-babel/test/test.js

@@ -136,4 +136,17 @@ describe( 'rollup-plugin-babel', function () {
 			assert.ok( !~cjs.indexOf( 'babelHelpers' ) );
 		});
 	});
+
+	it( 'correctly renames helpers (#22)', () => {
+		return rollup.rollup({
+			entry: 'samples/named-function-helper/main.js',
+			plugins: [ babelPlugin() ],
+			onwarn: function ( msg ) {
+				assert.equal( msg, `Treating 'babel-runtime/helpers/classCallCheck' as external dependency` );
+			}
+		}).then( function ( bundle ) {
+			var cjs = bundle.generate({ format: 'cjs' }).code;
+			assert.ok( !~cjs.indexOf( 'babelHelpers_get get' ), 'helper was incorrectly renamed' );
+		});
+	});
 });