Uncaught AssertionError: expected {} to equal 'testing' - node.js

Question

I'm not sure why it's saying the object is empty. This is my testing block of code.
describe("POST /users", () => {
let body = {
name: "testing",
email: "testing#testing.com",
password: 123456
};
it("Creates a new user", done => {
request(app)
.post("/register")
.send(body)
.end((err, res) => {
if (err) return done(err);
expect(res.body).to.be.equal("testing");
done();
});
});
});
Is there something I'm missing for the test to recognize the information being passed in? As in the payload since I thought that is what .send(payload) was for.
Thanks for the clarity.
** Update Controller and more information **
// Testing
let request = require("supertest");
let expect = require("chai").expect;
let app = require("../../server/server");
describe("GET /test", function() {
it("Returns a json for testing", done => {
request(app)
.get("/test")
.end((err, res) => {
done();
});
});
});
describe("POST /users", () => {
let body = {
name: "testing",
email: "testing#testing.com",
password: 123456
};
it("Creates a new user", done => {
request(app)
.post("/register")
.send(body)
.expect(res => {
expect(res.body).to.be.equal("testing");
})
.end(done);
});
});
// User routes
const express = require("express");
const router = express.Router();
// Load User Model
const User = require("../../models/User");
// #route GET api/users/test
// #desc Tests user route
// #access Public
router.get("/test", (req, res) => res.json({ msg: "Users Works" }));
router.post("/register", (req, res) => {
User.findOne({ email: req.body.email }).then(user => {
if (user) {
res.status(409).json({ msg: "User exist" });
} else {
const newUser = new User({
name: req.body.name,
email: req.body.email,
password: req.body.password
});
newUser
.save()
.then(user => res.status(200).send(user))
.catch(err => console.log(err));
}
});
});
module.exports = router;
// Server
const express = require("express");
const bodyParser = require("body-parser");
const mongoose = require("mongoose");
const app = express();
const users = require("./routes/api/users");
// Body Parser Middleware
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
// DB Config
const db = require("../config/keys").mongoURI;
// Connect to MongoDB Atlas
mongoose.connect(
db,
{ useNewUrlParser: true },
(err, client) => {
if (err) {
console.log("Error occurred while connecting to MongoDB Atlas...\n", err);
}
console.log("Connected...");
}
);
// Routes
app.use("/api/users", users);
const port = process.env.PORT || 5000;
let server = app.listen(port, () =>
console.log(`Server running on port ${port}`)
);
module.exports = server;