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https://github.com/maksimr/karma-image-snapshot

Karma jasmine matcher that performs image comparisons based on jest-image-snapshot for visual regression testing
https://github.com/maksimr/karma-image-snapshot

image-comparison jasmine karma snapshot-testing visual-regression-testing

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Karma jasmine matcher that performs image comparisons based on jest-image-snapshot for visual regression testing

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# karma-image-snapshot
![Test](https://github.com/maksimr/karma-image-snapshot/workflows/Test/badge.svg)
[![Open in Gitpod](https://img.shields.io/badge/Gitpod-Open%20in%20Gitpod-%230092CF.svg)](https://gitpod.io/#https://github.com/maksimr/karma-image-snapshot)
[![npm](https://img.shields.io/npm/v/karma-image-snapshot)](https://www.npmjs.com/package/karma-image-snapshot)

Jasmine matcher that performs image comparisons based
on [jest-image-snapshot](https://github.com/americanexpress/jest-image-snapshot) for visual regression testing

## How to use

```js
/** karma.config.js*/
module.exports = function(config) {
config.set({
frameworks: [/*✅*/'snapshot-jasmine', 'jasmine'],
/*...*/
snapshot: {
customSnapshotsDir: require('path').resolve(__dirname, '__image_snapshots__')
},
browsers: [/*✅*/'SnapshotLauncher' /* or SnapshotHeadlessLauncher*/]
});
};
```

If you want to automatically remove outdated snapshots you should add special reporter

```js
/** karma.config.js*/
module.exports = function(config) {
config.set({
/*...*/
reporters: [/*...*/, /*✅*/'outdated-snapshot']
});
};
```

Now you can use `window.screenshot`, `window.setViewport` functions and asynchronous jasmine matcher `toMatchImageSnapshot` in your tests

```js
/** example.e2e.js*/
it('should compare image snapshots', async function() {
/*...*/
const image = await window.screenshot();
await expectAsync(image).toMatchImageSnapshot();
});
```

Working configuration and test example you can find in `test` directory

## API

Available properties for `snapshot` and `toMatchImageSnapshot` you can look [here](https://github.com/americanexpress/jest-image-snapshot#%EF%B8%8F-api)

## Browser flags & options
You can tune browser settings through flags & options

```js
/** karma.config.js*/
module.exports = function(config) {
config.set({
/*...*/
customLaunchers: {
Chrome: {
base: 'SnapshotLauncher',
options: /*✅*/{
devtools: true
},
flags: [/*✅*/'--font-render-hinting=none', '--no-sandbox']
}
}
});
};
```

## Playwright

You can use playwright instead of puppeteer

```js
/** karma.config.js*/
module.exports = function(config) {
config.set({
/*...*/
customLaunchers: {
Firefox: {
base: 'SnapshotLauncher',
browserType: require('playwright').firefox
}
}
});
};
```