Checking function calling inside POST request handler - node.js

Question

I need to test that my POST /login handler calling validServiceURL function inside itself.
I tried to solve this issue using spy from sinon, but didn't manage it.
POST /login handler:
const login = async (req, res) => {
try {
if (await validServiceURL(req.headers.host)) {
await checkUser(req, res);
} else {
res.redirect("/");
}
} catch (err) {
reditectToHomePageWithError(res, err.message);
}
};
Test code:
const chai = require("chai");
const sinon = require("sinon");
const request = require("supertest");
chai.use(require("sinon-chai"));
const expect = chai.expect;
const app = require("../../app");
const validServiceURL = require("../../lib/validServiceURL");
const sandbox = sinon.createSandbox();
describe("User", function() {
describe("POST login", function() {
it("should call validServiceURL with provided serviceURL", async () => {
let args = { username: user.username, password: password };
let serviceURL = "http://127.0.0.1:3030";
let spyValidServiceURL = sandbox.spy(validServiceURL);
await request(app)
.post("/login")
.type("form")
.send(args)
.set("host", serviceURL);
expect(spyValidServiceURL).to.have.been.calledWith(serviceURL);
sandbox.restore();
});
});
});
When I run this test I get error look like:
AssertionError: expected validServiceURL to have been called with arguments http://127.0.0.1:3030

Answer 1

sinon doesn't support stub/spy a standalone function directly. In your case, the standalone function is validServiceURL. For more info, see this issue.
Here is the solution using proxyquire module:
app.js:
const express = require("express");
const validServiceURL = require("./validServiceURL");
const app = express();
async function checkUser(req, res) {
console.log("checkUser");
}
function reditectToHomePageWithError(res, message) {
console.log(message);
}
const login = async (req, res) => {
try {
if (await validServiceURL(req.headers.host)) {
await checkUser(req, res);
} else {
res.redirect("/");
}
} catch (err) {
reditectToHomePageWithError(res, err.message);
}
};
app.post("/login", login);
module.exports = app;
validServiceURL.js:
async function validServiceURL() {}
module.exports = validServiceURL;
app.test.js:
const chai = require("chai");
const sinon = require("sinon");
const request = require("supertest");
const proxyquire = require("proxyquire");
chai.use(require("sinon-chai"));
const expect = chai.expect;
const sandbox = sinon.createSandbox();
describe("User", function() {
describe("POST login", function() {
it("should call validServiceURL with provided serviceURL", async () => {
let args = { username: "username", password: "password" };
let serviceURL = "http://127.0.0.1:3030";
let spyValidServiceURL = sandbox.spy();
const app = proxyquire("./app", {
"./validServiceURL": spyValidServiceURL,
});
await request(app)
.post("/login")
.type("form")
.send(args)
.set("host", serviceURL);
expect(spyValidServiceURL).to.have.been.calledWith(serviceURL);
sandbox.restore();
});
});
});
Integration test result with coverage:
User
POST login
✓ should call validServiceURL with provided serviceURL (468ms)
1 passing (474ms)
--------------------|----------|----------|----------|----------|-------------------|
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s |
--------------------|----------|----------|----------|----------|-------------------|
All files | 87.1 | 50 | 57.14 | 87.1 | |
app.js | 69.23 | 50 | 33.33 | 69.23 | 6,10,16,21 |
app.test.js | 100 | 100 | 100 | 100 | |
validServiceURL.js | 100 | 100 | 0 | 100 | |
--------------------|----------|----------|----------|----------|-------------------|
Source code: https://github.com/mrdulin/mocha-chai-sinon-codelab/tree/master/src/stackoverflow/57908094