devextreme-screenshot-comparer

[![TypeScript version][ts-badge]][typescript-4-2]
[![Node.js version][nodejs-badge]][nodejs]

Usage

$3

```js
import {​​​​​​​ createScreenshotsComparer, compareScreenshot }​​​​​​​ from 'devextreme-screenshot-comparer';
test('Full size pager', async (t) => {​​​​​​​​
await t
.expect(await compareScreenshot(t, 'pager-full-allpages.png'))
}​​
``


$3


``js
// create comparer for collect results
const {​​​ takeScreenshot, compareResults }​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ = createScreenshotsComparer(t);
await t
... // perform test actions and take the first screenshot
.expect(await takeScreenshot('pager-1.png', pagerElement))
...// perform other actions and take the second one
.expect(await takeScreenshot('pager-2.png', pagerElement))
// check the result and show errors
.expect(compareResults.isValid())
.ok(compareResults.errorMessages());
``

Files and folders structure

`
.
+- testing -- default root path
+- tests
| +- etalons
| | +- pager-screehshot1.png
| +- pager.ts -- testfile with takeScreenshot(t, 'screehshot1');
+- screenshots
| +- pager-screehshot1.png
| +- pager-screehshot1.png
| +- pager-screehshot1_mask.png
| +- pager-screehshot1_text_mask.png
+- artifacts
+- compared-screenshots
| +- pager-screehshot1.png
| +- pager-screehshot1_etalon.png
| +- pager-screehshot1_mask.png
+- pager-screehshot1 - generated only when debug mode enabled;
+- ... -- step by step image transformations used for comparison;
+- log.txt -- comparison logs

`


Configuration

Default config:
``js
const screenshotComparerDefault = {
path: './testing',
screenshotsRelativePath: '/screenshots',
destinationRelativePath: '/artifacts/compared-screenshots',
generatePatch: false,
highlightColor: { r: 0xff, g: 0, b: 0xff },
maskRadius: 5,
attempts: 2,
attemptTimeout: 500,
looksSameComparisonOptions: {
strict: false,
tolerance: 5,
ignoreAntialiasing: true,
antialiasingTolerance: 5,
ignoreCaret: true,
},
textComparisonOptions: {
strict: false,
ignoreAntialiasing: true,
ignoreCaret: true,
},
enableTextMask: true,
textMaskRadius: 2,
textDiffTreshold: 0.05,
};
``

* Common options:
* path - path to the screenshots root folder;
* screenshotsRelativePath - a relative path for storing screenshots to compare (base part is the path property)
* destinationRelativePath - a relative path for storing comparison results (base part is the path property)
* generatePatch - save updated screenshots to the 'artifacts/screenshots' subfolder, keep etalon screenshots' tree hierarchy;
* maskRadius - radius of ignored pixels when using a mask file;
* attemps - count of attempts to get a valid screenshot;
* attempTimeout - timeout between attemps;
* ignoreSizeDifference - ignore the size difference between compared images
* looksSameComparisonOptions - see [look-same] for more details;
* Text comparison options:
* enableTextMask - if enabled, comparer generates a mask over text glyphs. Comparison inside the mask area ignores subpixel diffs;
* textMaskRadius - radius of the mask area around text glyph;
* textDiffTreshold - a value between [0..1]. 0 means that no diff allowed betwen original and current text glyphes, 1 ignores differences within the mask area at all;
* textComparisonOptions - see [look-same] for more details;

You can override the default configuration using .testcaferc.json. For example, override the path:
``json
{
"screenshots-comparer": {
"path": "./testing/testcafe"
}
}
``
or for any takeScreenshot call:
``js
.expect(await takeScreenshot('', null, { looksSameComparisonOptions: { tolerance: 30 } }));
```

License

DevExtreme Screenshot Comparer is released as MIT-licensed

[ts-badge]: https://img.shields.io/badge/TypeScript-4.2-blue.svg
[nodejs-badge]: https://img.shields.io/badge/Node.js->=%2014.16-blue.svg
[nodejs]: https://nodejs.org/dist/latest-v14.x/docs/api/
[typescript]: https://www.typescriptlang.org/
[typescript-4-2]: https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-2.html
[jest]: https://facebook.github.io/jest/
[eslint]: https://github.com/eslint/eslint
[gh-actions]: https://github.com/features/actions
[look-same]:https://www.npmjs.com/package/looks-same