This reverts commit 303c5998f8.
Reason for revert: I tried enabling `ssim-cie94` by default on
ionic-framework test suite, and it proves to be overly strict for their
usecase.
The method accepts a `ratio` option to assert the ratio
of the element in viewport. `ratio` defaults to `Number.MIN_VALUE`.
NOTE: this reverts commit d950f5b6ee and
adds `ratio` option support + does the rename.
Fixes#8740
The option defines a comparator to be used to compare images.
Possible values are `"pixelmatch"` and `"ssim-cie94"`.
Note: This reverts commit 8167f8bf54.
This is a new web-first assertion that should be used like this:
```ts
test('should work', async ({ page }) => {
const locator = page.locator('body');
// New web-first assertion.
await expect(locator).toIntersectViewport();
// The same functionality.
await expect.poll(() => locator.viewportRatio()).toBeGreaterThan(0);
});
```
Fixes#8740
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 configuration option allows to set a string with template
values for precise control over snapshot path location.
An example of `snapshotPathTemplate` usage:
```ts
// playwright.config.ts
// Notice the `testDir` configuration!
export default {
testDir: './tests',
snapshotPathTemplate: './__screenshots__/{platform}/{projectName}/{testFilePath}/{arg}{ext}',
}
```
Currently supported "magic tokens" inside the `snapshotPathTemplate`
are:
- `{testDir}` - project's `testDir`
- `{snapshotDir}` - project's `snapshotDir`
- `{platform}` - `process.platform`
- `{projectName}` - Project's sanitized name
- `{testFileDir}` - Directories in relative path from `testDir` to test
file path (e.g. `page/` in the example below)
- `{testFileName}` - Test file name (with extension) (e.g.
`page-click.spec.ts` in the example below)
- `{testFilePath}` - Relative path from `testDir` to test file path
(e.g. `page/page-click.spec.ts` in the example below)
- `{ext}` - snapshot extension (with dots)
- `{arg}` - joined snapshot name parts, without extension (e.g.
`foo/bar/baz` in the example below)
- `{snapshotSuffix}` - `testInfo.snapshotSuffix` value.
Consider the following file structure:
```
playwright.config.ts
tests/
└── page/
└── page-click.spec.ts
```
The following `page-click.spec.ts`:
```ts
// page-click.spec.ts
import { test, expect } from '@playwright/test';
test('should work', async ({ page }) => {
await expect(page).toHaveScreenshot(['foo', 'bar', 'baz.png']);
});
```
Fixes#7792
