A functional assertion and a visual assertion answer different questions. A checkout can save the correct order while its confirmation page clips the total on mobile. Visual Guard adds screenshot comparison to Python tests so a reviewed baseline can help catch that rendered change.
Use the current API
The repository documents VisualTester.assert_matches, with exclude_regions for masking. Pixel comparison is the default. This example assumes an authorized test application and a stable viewport; replace the sample URL with that application.
from selenium import webdriver
from visual_guard import VisualTester
def test_homepage_layout():
driver = webdriver.Chrome()
try:
driver.set_window_size(1280, 900)
driver.get("https://example.com")
# Wait for your application's stable ready state before capture.
visual = VisualTester()
visual.assert_matches(driver, "homepage")
finally:
driver.quit()Choose a comparison method
pip install "visual-guard[full]"# Integration snippet: driver and visual come from the setup above.
visual.assert_matches(driver, "homepage_ssim", method="ssim", threshold=0.95)
# Rectangle format is (x, y, width, height).
# Mask only content outside this checkpoint's requirements.
visual.assert_matches(
driver, "dashboard", exclude_regions=[(100, 50, 200, 30)]
)The SSIM value shown is an example to calibrate with known good and known bad screenshots. It is not a 95% correctness score. Verify optional dependencies and the active comparison method in your environment before interpreting results.
Make differences actionable
- Fix viewport, fonts, locale, theme, and fixture data.
- Wait for required images and asynchronous content.
- Keep baseline, actual, and diff artifacts associated with the application build.
- Review changes at representative mobile and desktop sizes.
- Keep outcome and accessibility checks alongside screenshot comparisons.
Masking can reduce noise but also removes evidence. Do not exclude a price, validation message, or action merely because it is dynamic. Validate the value independently and restrict the exclusion to what the visual checkpoint does not need to judge.
Reviewed against the current repository on September 5, 2026. No GitHub release was found during this review, so this article does not present the repository API as a newly published package release. Visual Guard usage and comparison guide.
