diff --git a/src/libs/lambda.test.ts b/src/libs/lambda.test.ts
new file mode 100644
index 0000000..b0a1ea5
--- /dev/null
+++ b/src/libs/lambda.test.ts
@@ -0,0 +1,22 @@
+import middy from '@middy/core';
+import middyJsonBodyParser from '@middy/http-json-body-parser';
+import { middyfy } from './lambda';
+
+jest.mock('@middy/core', () => {
+  const use = jest.fn().mockImplementation(() => 'middyfied handler');
+  return jest.fn().mockImplementation(() => ({ use }));
+});
+jest.mock('@middy/http-json-body-parser');
+
+const MOCK_MIDDY = middy as jest.MockedFunction<typeof middy>;
+
+describe('middyfy', () => {
+  it('should wrap handler with middy, apply JSON body parser, and return middy instance', () => {
+    const handler = jest.fn();
+    const middyfiedHandler = middyfy(handler);
+    expect(middy).toHaveBeenCalledWith(handler);
+    const mockMiddyInstance = MOCK_MIDDY.mock.results[0].value;
+    expect(mockMiddyInstance.use).toHaveBeenCalledWith(middyJsonBodyParser());
+    expect(middyfiedHandler).toBe('middyfied handler');
+  });
+});
diff --git a/tsconfig.json b/tsconfig.json
index 896f946..b2a9bd5 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -8,7 +8,8 @@
     "removeComments": true,
     "sourceMap": true,
     "target": "ES2020",
-    "outDir": "lib"
+    "outDir": "lib",
+    "esModuleInterop": true,
   },
   "include": ["src/**/*.ts", "serverless.ts"],
   "exclude": [