Coding and testing an authentication API [NodeJs + Cypress]

Build an authentication API with Node.js that supports user registration and login via a RESTful interface. Learn to test the code with Cypress to ensure changes keep working.

Initialize the project with npm, install express and nodemon, create index.js, and set the app to listen on port 3000 to start and test the server.

Create a first register endpoint with express router to let users sign up, wiring a post route /api/user/register and integrating routes into the index file.

Discover end-to-end API testing for authentication endpoints by using postman for manual requests and Cypress for automated tests, including posting to localhost:3000/api/user/register and validating responses.

Update Cypress tests to ensure the register endpoint returns 200 for an authentication API, then run and inspect reports from the command line and add mongoose to package.json for testing.

Create a free MongoDB cluster, set up database access, install mongoose, and connect with mongoose.connect using the URI and database name to verify the connection.

Install dotenv, load environment variables from a .env file, replace the database connection string with a secret named dbi_conn, reference it via process.env, and add .gitignore to keep it private.

Create a Mongoose user model with name, email, password and date fields, export it, and implement a register endpoint that validates input, saves the user, and returns the saved record.

Write and run API tests with positive and negative cases using Cypress in Node.js, practicing unit, integration, and acceptance tests, including boundary value analysis and handling 400 and 200 responses.

Strengthen authentication API tests by validating status codes and full response objects (name, email, password) for create user, and discuss measuring code coverage.

Remove duplication by wrapping tests into a user/register describe block and reusing a register helper to cleanly organize Cypress tests for the authentication API.

Implement body validation for user creation with a schema-based validation library, enforcing name, email, and password rules, returning 400 with error details when validation fails and verifying with postman tests.

Create a creation validation test for the authentication API in Node.js with Cypress, validating required fields and minimum lengths, and asserting 400 errors with precise messages while avoiding third‑party validation.

Extract validation logic into a separate data validation class to support reusable login validation, and enable Cypress automated tests to rerun on file changes for reliable feedback.

Implement pre-checks to avoid duplicate user creation by validating email existence, return 400 'user email already registered,' and use dynamic GoED-based emails for robust tests.

Encrypt passwords before saving to the database, avoiding plaintext storage; implement encryption with a script and npm packages, and verify via tests that encrypted passwords are stored.

Build a new login endpoint as a post route, add login validation, verify email exists, compare passwords with bcrypt, and return proper errors (400 for invalid details, 401 for unauthorized).

Develops a positive test for the login endpoint of the authentication API using Cypress, posting a registered user and validating a 200 response and authentication flow, while keeping tests clean.

Learn how to add a jwt token to login, sign token with a secret, include user id, return token in response header, and set an expiration for secure authentication.