PostgreSQL in Cypress E2E Testing: A Step-by-Step Guide

2 min readAug 21, 2023

Cypress is a powerful end-to-end testing framework that allows developers to write and execute tests for web applications. In some cases, you might need to interact with a PostgreSQL database during your tests to perform various tasks such as verifying data integrity or validating application behavior. In this guide, we’ll explore how to integrate PostgreSQL with Cypress for efficient database testing using a real-world example.

Prerequisites

Node.js and npm installed on your machine.
Basic understanding of Cypress and E2E testing concepts.

Step 1: Setting Up the PostgreSQL Connection

We’ll start by setting up a connection to a PostgreSQL database. To achieve this, we’ll use the pg-promise library.

Install the required packages:

npm install pg-promise

2. Create a PostgreSQL configuration file, e.g., dbConfig.js:

// dbConfig.js
const pgp = require('pg-promise');

const dbConfig = {
  dbHost: 'your-database-host',
  dbLogin: 'your-database-login',
  dbPassword: 'your-database-password',
  dbName: 'your-database-name',
  dbPort: 5432,
};

const connectionString = `postgres://${dbConfig.dbLogin}:${dbConfig.dbPassword}@${dbConfig.dbHost}:${dbConfig.dbPort}/${dbConfig.dbName}`;
const db = pgp()(connectionString);

module.exports = { db };

Step 2: Cypress Configuration

Set up the cypress.config.js file to include the PostgreSQL connection setup:

// cypress.config.js
const pgp = require('pg-promise');
const { db } = require('./dbConfig');

module.exports = {
  e2e: {
    baseUrl: 'your-website-baseUrl',
    setupNodeEvents(on, config) {
      on('task', {
        queryDatabase({ email }) {
          const query = 'SELECT * From Users'; // any query you want to check
          return db.oneOrNone(query, email);
        },
      });
    },
    defaultCommandTimeout: 20000,
  },
};

Step 3: Writing Cypress Tests

Now, let’s write a Cypress test that demonstrates how to register a new user, fetch their verification code from the database, and perform verification using the fetched verification code.

Create a test spec file, e.g., userRegistration.spec.js:

// userRegistration.spec.js
describe('User Registration and Verification', () => {
  it('should register a new user, fetch verification code, and confirm registration', () => {
    const randomEmail = `testuser_${Cypress._.random(1000, 9999)}@example.com`;

    // Step 1: Register a new user (you can replace this with your application's registration logic)
    // ... your registration logic ...

    // Step 2: Fetch verification code using cy.task()
    cy.task('queryDatabase', { email: randomEmail }).then((queryResponse) => {
      // Log the query response
      cy.log('Query Response:', queryResponse);

      // Ensure verification code was fetched successfully
      expect(queryResponse).to.not.be.null;

      const verificationCode = queryResponse.VerificationCode;

      // Step 3: Perform verification using the fetched verification code
      // ... your verification logic ...

      // Example assertion:
      expect(verificationSuccessful).to.be.true;
    });
  });
});

Conclusion

Integrating PostgreSQL with Cypress enables you to perform powerful database testing alongside your web application tests. By following the steps outlined in this guide, you can seamlessly interact with a PostgreSQL database during your Cypress E2E tests, enhancing your ability to ensure the quality and reliability of your web application.