This patch adds a grid border around the image so that the SSIM
resolution doesn't drop for the border pixels.
We also add a test with WebKit rendering artifacts to make sure
new approach helps to fight this.
While migrating Playwright tests from pixelmatch comparator to the
ssim-cie94 comparator, we noticed a rendering artifact that happens
on playwright screenshot tests on WebKit Linux.
This PR adds a set of cropped-down examples and tunes the ssim-cie94
comparator to accept these rendering artifacts.
This patch implements a new image comparison function, codenamed
"ssim-cie94". The goal of the new comparison function is to cancel out
browser non-determenistic rendering.
To use the new comparison function:
```ts
await expect(page).toHaveScreenshot({
comparator: 'ssim-cie94',
});
```
As of Nov 30, 2022, we identified the following sources of
non-determenistic rendering for Chromium:
- Anti-aliasing for certain shapes might be different due to the
way skia rasterizes certain shapes.
- Color blending might be different on `x86` and `aarch64`
architectures.
The new function employs a few heuristics to fight these
differences.
Consider two non-equal image pixels `(r1, g1, b1)` and `(r2, g2, b2)`:
1. If the [CIE94] metric is less then 1.0, then we consider these pixels
**EQUAL**. (The value `1.0` is the [just-noticeable difference] for
[CIE94].). Otherwise, proceed to next step.
1. If all the 8 neighbors of the first pixel match its color, or
if the 8 neighbors of the second pixel match its color, then these
pixels are **DIFFERENT**. (In case of anti-aliasing, some of the
direct neighbors have to be blended up or down.) Otherwise, proceed
to next step.
1. If SSIM in some locality around the different pixels is more than
0.99, then consider this pixels to be **EQUAL**. Otherwise, mark them
as **DIFFERENT**. (Local SSIM for anti-aliased pixels turns out to be
very close to 1.0).
[CIE94]: https://en.wikipedia.org/wiki/Color_difference#CIE94
[just-noticeable difference]:
https://en.wikipedia.org/wiki/Just-noticeable_difference
This prevents shared workers from stalling upon restart.
We receive `Inspector.targetCrashed` and
`Inspector.targetReloadedAfterCrash` events that assume
`Runtime.runIfWaitingForDebugger` from any attached client. It is easier
and more stable to just detach from shared workers, because we do not
inspect them.
For service workers, we should actually issue
`Runtime.runIfWaitingForDebugger` in such cases, because we attach to
them.
Fixes#18932.
The behavior regarding filters (both in config, command line and .only)
is the following:
- if some of tests match and none of setup match then we'll run all
setup files and all matching tests
- otherwise the filters apply to setup files the same way as to regular
tests
- Properly convert coordinates for iframes with non-zero borders.
- IFrames that have `transform` anywhere in the ancestors skip
`hitPoint`-based check because we cannot reliably translate the viewport
point into frame document's coordinates.
Fixes#18245.
Running `npx playwright test file:123` will have the following behavior
- if only test files match then only matching subset of tests will run
but all setup files will run as well
- if only setup files match the filter then only those setup tests will
run
- if both setup and test files match an error will be thrown
