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
This patch:
- starts using directory of `package.json` to resolve default
output directory path
- starts using either `package.json` directory or configuration
directory to resolve all relative paths
References #12970
This patch:
- Enables configuration of certain defaults for some options of `expect.toHaveScreenshot` method via `TestProject.expect.toHaveScreenshot` property
- Sets sensible defaults for these options:
* `fonts: "ready"`
* `animations: "disabled"`
* `size: "css"`
This patch reverts 2 commits that removed the feature from the method:
- "fix: explicitly ignore maxDiffPixels in toMatchSnapshot (#12570)"
commit b8af8458d614dcc53ef324553d63522448e94d94.
- "chore: remove `maxDiffPixels` from toMatchSnapshot (#12539)"
commit a3dff45974d53087bd6ebea5164c75d5eb357e28.
The `screenshotsDir` option controls the expectation storage
for `toHaveScreenshot()` function.
The new expectation management for screenshots has the following
key properties:
- All screenshots are stored in a single folder called `screenshotsDir`.
- Screenshot names **do not** respect `snapshotDir` and `snapshotSuffix`
configurations.
- `screenshotsDir` is configurable per project. This way a "smoke tests"
project can re-use screenshots from "all tests" project.
- Host platform is a top-level folder.
For example, given the following config:
```js
// playwright.config.ts
module.exports = {
projects: [
{ name: 'Mobile Safari' },
{ name: 'Desktop Chrome' },
],
};
```
And the following test structure:
```
smoke-tests/
└── basic.spec.ts
```
Will result in the following screenshots folder structure by default:
```
__screenshots__/
└── darwin/
├── Mobile Safari/
│ └── smoke-tests/
│ └── basic.spec.ts/
│ └── screenshot-expectation.png
└── Desktop Chrome/
└── smoke-tests/
└── basic.spec.ts/
└── screenshot-expectation.png
```
This patch adds additional options to `toMatchSnapshot` method:
- `pixelCount` - acceptable number of pixels that differ to still
consider images equal. Unset by default.
- `pixelRatio` - acceptable ratio of all image pixels (from 0 to 1) that differ to still
consider images equal. Unset by default.
Fixes#12167, #10219
