Question 1

How to integrate reg-cli with Puppeteer for visual testing?

Accepted Answer

Use Puppeteer to capture screenshots and save them to a directory, then run reg-cli to compare these actual images against expected baselines. Automate this in a script that chains Puppeteer commands with reg-cli's comparison options, and use -R for HTML reports to review differences.

Question 2

reg-cli vs Percy: which is better for visual regression testing?

Accepted Answer

reg-cli is a lightweight, self-hosted CLI tool ideal for teams wanting control and simplicity with Node.js integration, while Percy is a cloud-based service with built-in screenshot capture, collaboration, and cross-browser testing. Choose reg-cli for cost-effectiveness and Percy for an all-in-one solution with less manual setup.

Question 3

How to set up reg-cli in a CI/CD pipeline like GitHub Actions?

Accepted Answer

Install reg-cli as a dev dependency, then add a step in your workflow YAML to run the comparison command with paths for actual, expected, and diff directories. Use options like -R for HTML reports and -I to ignore changes if needed, and ensure expected images are version-controlled or cached between runs.

Question 4

What are the best threshold settings in reg-cli to avoid false positives?

Accepted Answer

Start with default settings (0 for thresholds) and adjust based on your UI's stability. Use matchingThreshold (-M) for pixel sensitivity, thresholdRate (-T) for difference ratio, and thresholdPixel (-S) for absolute pixel count, testing with known changes to balance detection accuracy and false positives.

Question 5

Can reg-cli handle anti-aliasing differences in screenshots?

Accepted Answer

Yes, reg-cli has an enableAntialias option (-A) that can be set to true to account for anti-aliasing variations, but this is experimental and may need careful tuning to avoid masking real visual differences, as noted in the README.

Question 6

How to generate reports from existing JSON data with reg-cli?

Accepted Answer

Use the -F option followed by the JSON file path (e.g., -F ./reg.json) along with -R for the HTML report output. This allows creating reports without re-comparing images, useful for reusing or sharing previous test results, as detailed in the 'from json' section of the README.

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