Unlocking Greater Confidence in Your Releases

The Importance of Visual Confirmation

As developers, we strive to ensure our applications and sites function as expected for every user. We write tests to gain confidence in our code, but often overlook a crucial aspect: visually confirming that the design looks as intended. While unit, integration, and end-to-end tests are essential, they don’t guarantee a flawless user experience.

The Missing Piece: Visual Regression Testing

Traditional testing methods focus on functionality, but neglect the visual aspects of our applications. This oversight can lead to unexpected changes in appearance, compromising the user experience. To address this, we need to incorporate visual regression testing into our workflows.

Automating Visual Regression Tests

Manually checking every possible user journey is impractical. Instead, we can leverage automated visual regression testing to ensure our applications appear as designed. This approach involves comparing screenshots of our application to a baseline, detecting any visual differences.

A Simple Solution

We can set up a simple visual regression testing process using Jest and a few libraries. By installing the necessary dependencies and updating our Jest configuration, we can create image snapshots of our application and assert that they match the expected visuals.

// Install required dependencies
npm install jest-image-snapshot --save-dev

// Update Jest configuration
module.exports = {
  //...
  snapshotSerializers: ['jest-image-snapshot'],
};

The Challenge of Environments

However, this approach faces a significant challenge: differing compute environments can render our application slightly differently, causing tests to fail. To overcome this, we can utilize Docker containers to ensure consistent rendering across environments.

FROM node:14

# Set working directory to /app
WORKDIR /app

# Copy package*.json
COPY package*.json./

# Install dependencies
RUN npm install

# Copy application code
COPY..

# Run application
CMD ["npm", "start"]

CI/CD Integration

By integrating our visual regression tests with CI/CD tools, we can automate testing and ensure our application appears as intended in different environments.

name: Visual Regression Testing

on: [push]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v2
      - name: Install dependencies
        run: npm install
      - name: Run visual regression tests
        run: npm run test:visual

Delivering Exceptional User Experiences

By incorporating visual regression testing into our workflows, we can unlock greater confidence in our releases and deliver exceptional user experiences. This approach provides an effective solution for automating visual regression tests, ensuring our applications appear as intended across different environments.