Testing with Mocha and Chai consuming values from previous tests - node.js

Question

I have some tests created with mocha and chai using TypeScript, they actually work as expected. Each function returns a Promise which runs a test.
My question is if is there anyway to consume on each test the value returned by a previous test without using the nesting you see below.
My concern is that if I have more test the nesting code could be very annoying going to the right
import * as request from 'supertest';
import app from '../src/app';
import { Promise } from 'bluebird';
import * as dateformat from 'dateformat';
import Commons from '../../utils/commons';
import { expect } from 'chai';
...
// all the functions used below are defined over here
...
registerNonExistingUser(email, pass, role).then(
(jwtToken: string) => {
authenticateUserCorrectJwt(jwtToken).then(
(user) => {
authenticateUserWrongJwt().then(
() => {
loginUserWrongCredentials().then(
() => {
loginUserCorrectCredentials(email, pass).then(
(jwtToken: string) => {
getLocalUserInfoCorrectJwt(jwtToken, email).then(
(user) => {
createTodoAsEditor(jwtToken, todoTitle).then(
(todos) => {
checkTodoExistsWithCorrectTitle(jwtToken, todoTitle).then(
(todo: any) => {
deleteTodoWithCorrectIdAsEditor(jwtToken, todo._id).then(
(todo) => {
unregisterExistingUser({
'local.email': email,
}).then(
(user) => {
// console.log(Commons.stringify(user));
}
);
}
);
}
);
}
);
}
);
}
);
}
);
}
);
}
);
}
);
Any idea on how to beautify this?
[EDIT 1]
#bhoo-day suggestion did the trick:
registerNonExistingUser(email, pass, role)
.then((_jwtToken: string) => {
return authenticateUserCorrectJwt(_jwtToken);
})
.then((user) => {
return authenticateUserWrongJwt();
})
...
Now I'm wondering if I could transform the beginning of the chain, in order to be something like the following (which I tried but doesn't work). My goal is to put every function at the same level, including the very first function:
Promise.resolve()
.then(() => {
return registerNonExistingUser(email, pass, role);
})
.then((jwtToken: string) => {
return authenticateUserCorrectJwt(jwtToken);
})
.then((user) => {
return authenticateUserWrongJwt();
})
...
[EDIT 2]
I tried the following and it works. Do you have any idea on how to simplify it?, maybe using: Promise.resolve()...?
new Promise((resolve) => {
it('dummy', (done) => { resolve(); return done(); });
})
.then(() => {
return registerNonExistingUser(email, pass, role);
})
.then((_jwtToken: string) => {
return authenticateUserCorrectJwt(_jwtToken);
})
Thanks!

Answer 1

If you use promise, you could avoid this callback hell because that is the main purpose of promise.
Some ideas to solve the issue.
// temp variable to store jwt token
let token;
registerNonExistingUser(email, pass, role)
.then((jwtToken: string) => {
token = jwtToken; // assign it so other functions can use it
return authenticateUserCorrectJwt(jwtToken)
})
.then((user) => authenticateUserWrongJwt())
.then(() => loginUserWrongCredentials())
.then(() => loginUserCorrectCredentials(email, pass))
.then((jwtToken: string) => getLocalUserInfoCorrectJwt(jwtToken, email))
.then((user) => createTodoAsEditor(token, todoTitle))
.then((todos) => checkTodoExistsWithCorrectTitle(token, todoTitle))
.then((todo: any) => deleteTodoWithCorrectIdAsEditor(token, todo._id))
.then((todo) => unregisterExistingUser({ 'local.email': email }))
.then((user) => {
// console.log(Commons.stringify(user));
});
or if you use node 7.6.0 or higher, you can use async/await. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/await
async function printUser() {
try {
let jwtToken = await registerNonExistingUser(email, pass, role);
const user = await authenticateUserCorrectJwt(jwtToken);
await loginUserWrongCredentials();
jwtToken = await loginUserCorrectCredentials(email, pass);
const user = await getLocalUserInfoCorrectJwt(jwtToken, email);
const todos = await createTodoAsEditor(token, todoTitle);
const todo = await checkTodoExistsWithCorrectTitle(token, todoTitle)
const todo = await deleteTodoWithCorrectIdAsEditor(token, todo._id);
const user = await unregisterExistingUser({ 'local.email': email });
console.log(Commons.stringify(user));
} catch (error) {
// catch error here
}
}