Supertest — API Integration Testing

npm install -D supertest
npm install -D @types/supertest

import request from "supertest";
import app from "./app";

describe("User API", () => {
  it("GET /users returns users", async () => {
    const res = await request(app).get("/users");
    expect(res.status).toBe(200);
    expect(res.body).toHaveProperty("users");
  });

  it("POST /users creates user", async () => {
    const res = await request(app)
      .post("/users")
      .send({ name: "Alice", email: "alice@example.com" });
    expect(res.status).toBe(201);
    expect(res.body.id).toBeDefined();
  });

  it("GET /users/:id returns user", async () => {
    const res = await request(app).get("/users/1");
    expect(res.status).toBe(200);
    expect(res.body.id).toBe(1);
  });

  it("GET /users/999 returns 404", async () => {
    const res = await request(app).get("/users/999");
    expect(res.status).toBe(404);
  });
});

// With authentication
it("protected endpoint requires auth", async () => {
  const res = await request(app)
    .get("/admin")
    .set("Authorization", "Bearer invalid");
  expect(res.status).toBe(401);
});

// File upload
it("uploads file", async () => {
  const res = await request(app)
    .post("/upload")
    .attach("file", "./test.txt");
  expect(res.status).toBe(200);
});

// Form data
it("submits form", async () => {
  const res = await request(app)
    .post("/form")
    .field("name", "Alice")
    .field("email", "alice@example.com");
  expect(res.status).toBe(200);
});