test: added supertest

src/server/server.test.ts

@@ -0,0 +1,26 @@
+import requests from 'supertest';
+import server from './server';
+
+beforeAll(() => {
+  jest.mock('../utils/addition', () => ({
+    addition: jest.fn((value: number) => value + 1)
+  }));
+});
+
+afterAll(() => {
+  jest.clearAllMocks();
+});
+
+describe('server', () => {
+  it('returns input value increased by one', async () => {
+    const value = 1;
+    const res = await requests(server)
+      .post('/')
+      .send({ value: value })
+      .set('Content-Type', 'application/json')
+      .set('Accept', 'application/json');
+
+    expect(res.body.response).toBeDefined();
+    expect(res.body.response).toBe(value + 1);
+  });
+});