Express.js Middleware Unit Test Example

middleware.spec.ts

import sinon from 'sinon';
import { mockReq, mockRes } from 'sinon-express-mock';
import {handleSAMLPost, validateSubdomain} from "./login.handler";

describe("login.spec", () => {
    describe("validateSubdomain Middleware", () => {
        test("should allow request to continue if request comes from a valid subdomain", () => {
            const request = mockReq({
                hostname: "octan.localhost"
            });
            const response = mockRes();
            const next = jest.fn();

            validateSubdomain(request, response, next);

            expect(next).toHaveBeenCalledWith();
            sinon.assert.notCalled(response.sendStatus);
        });

        test("should return a 404 if request comes from an unknown/invalid subdomain", () => {
            const request = mockReq({
                hostname: "doesnotexist.localhost"
            });
            const response = mockRes();
            const next = jest.fn();

            validateSubdomain(request, response, next);
            expect(next).not.toHaveBeenCalled();
            sinon.assert.calledOnce(response.sendStatus);
            sinon.assert.calledWith(response.sendStatus, 404);
        });
    });

    describe("initSAMLRequest", () => {
        test("should return 200 status", () => {
            const request = mockReq();
            const response = mockRes();

            handleSAMLPost(request, response);
            sinon.assert.calledOnce(response.sendStatus);
            sinon.assert.calledWith(response.sendStatus, 200);
        });
    });
});