Compare deliberately
Channel deltas or YIQ comparison with allowed-pixel limits.
Visual regression testing · Ruby
See the pixels that changed.
Compare rendered images in Ruby and turn mismatches into useful diffs.
gem install lookalike
A mismatch should be actionable.
Choose pixel or perceptual comparison, set tolerances, and inspect the affected region.
Get useful output
Bounding boxes, diff images, and optional antialiasing detection.
Fit your test stack
RSpec, Minitest, Test::Unit, and local snapshot approval.
A small first step
Start with one example.
Install the gem, then follow the project guide for platform requirements and the full API.
require "lookalike"
require "tessel"
actual = Tessel.read("actual.png")
result = Lookalike.compare(
"expected.png", actual,
mode: :channel, max_delta: 1
)
abort result.inspect unless result.match?