Make it possible to parse ES module syntax

index.js

@@ -204,7 +204,7 @@ function createGlobalAssignmentASTNode(functionName) {
 }
 
 exports.generate = function(source, options = { comment: false, autoGlobalExports: false }){
-  const ast = esprima.parseScript(source, { attachComment: options.comment });
+  const ast = esprima.parseModule(source, { attachComment: options.comment });
   const functions = generateStubs(ast, options);
   const globalAssignments = options.autoGlobalExports ? generateGlobalAssignments(ast, options) : undefined;
   return {

test/fixtures/esm-expected.js

@@ -0,0 +1,6 @@
+/**
+ * Leading Block Comment for foo.
+ */
+// leading line comment for foo
+function foo() {
+}

test/fixtures/esm-exports.js

@@ -0,0 +1 @@
+export const foo = () => 'foo';

test/fixtures/esm-source.js

@@ -0,0 +1,7 @@
+import { foo } from './esm-exports';
+
+/**
+ * Leading Block Comment for foo.
+ */
+// leading line comment for foo
+global.foo = foo;

test/index.test.js

@@ -20,3 +20,12 @@ test('generate function generate entry functions from global assignments', funct
   t.equal(output.globalAssignments, undefined, 'actual output will match expected');
   t.end();
 });
+
+test('Can parse ES module syntax', function(t) {
+  const source = fs.readFileSync(__dirname + '/fixtures/esm-source.js', {encoding: 'utf8'});
+  const expected = fs.readFileSync(__dirname + '/fixtures/esm-expected.js', {encoding: 'utf8'});
+  const output = generate(source, { comment: true });
+  t.equal(output.entryPointFunctions, expected, 'actual output will match expected');
+  t.equal(output.globalAssignments, undefined, 'actual output will match expected');
+  t.end();
+});