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playwright/docs/src/api/class-snapshotassertions.md
Andrey Lushnikov fdcd7b549d
chore: mark comparator option back as experimental (#20816) 
This reverts commit 303c5998f8b747e94ac80e2e02c53b47ded11322.

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.
2023-02-13 11:11:44 -08:00

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class: SnapshotAssertions

  • since: v1.20
  • langs: js

Playwright provides methods for comparing page and element screenshots with expected values stored in files.

expect(screenshot).toMatchSnapshot('landing-page.png');

method: SnapshotAssertions.toMatchSnapshot#1

  • since: v1.22

Ensures that passed value, either a [string] or a [Buffer], matches the expected snapshot stored in the test snapshots directory.

Usage

// Basic usage.
expect(await page.screenshot()).toMatchSnapshot('landing-page.png');

// Pass options to customize the snapshot comparison and have a generated name.
expect(await page.screenshot()).toMatchSnapshot('landing-page.png', {
  maxDiffPixels: 27, // allow no more than 27 different pixels.
});

// Configure image matching threshold.
expect(await page.screenshot()).toMatchSnapshot('landing-page.png', { threshold: 0.3 });

// Bring some structure to your snapshot files by passing file path segments.
expect(await page.screenshot()).toMatchSnapshot(['landing', 'step2.png']);
expect(await page.screenshot()).toMatchSnapshot(['landing', 'step3.png']);

Learn more about visual comparisons.

Note that matching snapshots only work with Playwright test runner.

param: SnapshotAssertions.toMatchSnapshot#1.name

  • since: v1.22
  • name <[string]|[Array]<[string]>>

Snapshot name.

option: SnapshotAssertions.toMatchSnapshot#1.maxDiffPixels = %%-assertions-max-diff-pixels-%%

  • since: v1.22

option: SnapshotAssertions.toMatchSnapshot#1.maxDiffPixelRatio = %%-assertions-max-diff-pixel-ratio-%%

  • since: v1.22

option: SnapshotAssertions.toMatchSnapshot#1.threshold = %%-assertions-threshold-%%

  • since: v1.22

method: SnapshotAssertions.toMatchSnapshot#2

  • since: v1.22

Ensures that passed value, either a [string] or a [Buffer], matches the expected snapshot stored in the test snapshots directory.

Usage

// Basic usage and the file name is derived from the test name.
expect(await page.screenshot()).toMatchSnapshot();

// Pass options to customize the snapshot comparison and have a generated name.
expect(await page.screenshot()).toMatchSnapshot({
  maxDiffPixels: 27, // allow no more than 27 different pixels.
});

// Configure image matching threshold and snapshot name.
expect(await page.screenshot()).toMatchSnapshot({
  name: 'landing-page.png',
  threshold: 0.3,
});

Learn more about visual comparisons.

Note that matching snapshots only work with Playwright test runner.

option: SnapshotAssertions.toMatchSnapshot#2.maxDiffPixels = %%-assertions-max-diff-pixels-%%

  • since: v1.22

option: SnapshotAssertions.toMatchSnapshot#2.maxDiffPixelRatio = %%-assertions-max-diff-pixel-ratio-%%

  • since: v1.22

option: SnapshotAssertions.toMatchSnapshot#2.name

  • since: v1.22
  • name <[string]|[Array]<[string]>>

Snapshot name. If not passed, the test name and ordinals are used when called multiple times.

option: SnapshotAssertions.toMatchSnapshot#2.threshold = %%-assertions-threshold-%%

  • since: v1.22