diff --git a/src/index.js b/src/index.js
index 83c7d10..472e6cc 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,7 +1,12 @@
 function a() {
     console.log('a', eval(window.data));
 }
+function b() {
+    console.log('a', eval(window.data));
+}
+
 
 module.exports = {
-    a
+    a,
+    b
 }
\ No newline at end of file
diff --git a/tests/index.test.js b/tests/index.test.js
index 0aef01d..734089b 100644
--- a/tests/index.test.js
+++ b/tests/index.test.js
@@ -4,5 +4,6 @@ describe('a', () => {
     it('test', () => {
         // is function
         expect(a).toBeInstanceOf(Function)
+        expect(a()).toBeUndefined()
     })
 })
\ No newline at end of file