Setup

App Testing

Write unit or integration tests for your apps without binding a port.

Setup

Here's an example app:

// app.ts
import { createApp } from "@aklinker1/zeta";
import { z } from "zod";

export const app = createApp().get(
  "/health",
  {
    operationId: "healthCheck",
    responses: z.object({
      status: z.string(),
    }),
  },
  () => ({ status: "OK" }),
);

Inside your test file, import your app and call build() to create your app's fetch function. Then just call the fetch function with a Request object!

// app.test.ts
import { HttpStatus } from "@aklinker1/zeta/status";
import { app } from "./app";
import { describe, it } from "bun:test";

const fetch = app.build();

describe("App", () => {
  describe("healthCheck", () => {
    it("should return OK", async () => {
      const request = new Request("http://localhost/health");

      const response = await fetch(request);

      expect(response.status).toBe(HttpStatus.Ok);
      expect(await response.json()).toEqual({ status: "OK" });
    });
  });

  describe("Unknown route", () => {
    it("should return 404", async () => {
      const request = new Request("http://localhost/unknown");

      const response = await fetch(request);

      expect(response.status).toBe(HttpStatus.NotFound);
      expect(await response.json()).toMatchObject({
        error: "Not Found",
      });
    });
  });
});

WARNING

Only call build() once per app, otherwise it will throw an error.

Note that fetch always returns a Response, even if an error is thrown, like when a route is not found.

Next Steps

Testing the app like this works just fine, but it can be quite tedious to build the Request object and parse the response body inside every test. It's important to know you can do this, but Zeta provides a more convenient way to test your app with it's built-in test client.