gemini
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UI Screenshot testing utility
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# Gemini
[](https://www.npmjs.com/package/gemini)
[](https://travis-ci.org/gemini-testing/gemini)
[](https://coveralls.io/r/gemini-testing/gemini)
[](https://gitter.im/gemini-testing/gemini?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
[](http://waffle.io/gemini-testing/gemini)
[Gemini](https://github.com/gemini-testing/gemini) is a utility for regression
testing the visual appearance of web pages.
Gemini allows you to:
* Work with different browsers:
- Google Chrome (tested in latest version)
- Mozilla Firefox (tested in latest version)
- IE8+
- Opera 12+
* Test separate sections of a web page
* Include the `box-shadow` and `outline` properties when calculating element position and size
* Ignore some special case differences between images (rendering artifacts, text caret,
etc.)
* Gather CSS test coverage statistics
**Gemini** was created at [Yandex](http://www.yandex.com/) and is especially
useful to UI library developers.
## Quick start
### Installing
```
npm install -g gemini
npm install -g selenium-standalone
selenium-standalone install
```
### Configuring
Put the `.gemini.js` file in the root of your project:
```javascript
module.exports = {
rootUrl: 'http://yandex.ru',
gridUrl: 'http://127.0.0.1:4444/wd/hub',
browsers: {
chrome: {
desiredCapabilities: {
browserName: 'chrome'
}
}
}
};
```
### Writing tests
Write a test and put it in the `gemini` folder in the root of your project:
```javascript
gemini.suite('yandex-search', (suite) => {
suite.setUrl('/')
.setCaptureElements('.home-logo')
.capture('plain');
});
```
### Saving reference images
You have written a new test and should save a reference image for it:
```
gemini update
```
### Running tests
Start `selenium-standalone` in a separate tab before running the tests:
```
selenium-standalone start
```
Run gemini tests:
```
gemini test
```
## Dependencies
Required software:
1. WebDriver server implementation. There are several options:
- [Selenium Server](http://docs.seleniumhq.org/download/) — for testing in
different browsers. Launch with the `selenium-standalone start` command (if you will get error like "No Java runtime present, requesting install." you should install [Java Development Kit (JDK)](https://www.oracle.com/technetwork/java/javase/downloads/index.html) for your OS.).
- [ChromeDriver](https://sites.google.com/a/chromium.org/chromedriver/) — for
testing in Google Chrome. Launch with the `chromedriver --port=4444 --url-base=wd/hub` command.
- [PhantomJS](http://phantomjs.org/) — launch with the `phantomjs
--webdriver=4444` command.
- Cloud WebDriver services, such as
[SauceLabs](http://saucelabs.com/) or
[BrowserStack](http://www.browserstack.com/)
2. Compiler with support for C++11 (`GCC@4.6` or higher). This is a
[png-img](https://github.com/gemini-testing/png-img) requirement.
Compiling on Windows machines requires the [node-gyp prerequisites](https://github.com/nodejs/node-gyp#on-windows).
## Installing
To install the utility, use the [npm](https://www.npmjs.org/) `install` command:
```sh
npm install -g gemini
```
Global installation is used for launching commands.
## Configuring
**Gemini** is configured using a config file at the root of the project.
Gemini can use one of the following files:
* `.gemini.conf.js`
* `.gemini.conf.json`
* `.gemini.conf.yml`
* `.gemini.js`
* `.gemini.json`
* `.gemini.yml`
Let's say we want to run our tests only in the locally installed `PhantomJS`.
In this case, the minimal configuration file will only need to have the root URL
of your web app and the WebDriver capabilities of `PhantomJS`:
For example,
```yaml
rootUrl: http://yandex.com
browsers:
PhantomJS:
desiredCapabilities:
browserName: phantomjs
```
Also, you need to run `PhantomJS` manually in `WebDriver` mode:
```
phantomjs --webdriver=4444
```
If you are using a remote WebDriver server, you can specify its URL with the
`gridUrl` option:
```yaml
rootUrl: http://yandex.com
gridUrl: http://selenium.example.com:4444/wd/hub
browsers:
chrome:
desiredCapabilities:
browserName: chrome
version: "45.0"
firefox:
desiredCapabilities:
browserName: firefox
version: "39.0"
```
You can also set up each browser to have its own node:
```yaml
rootUrl: http://yandex.com
browsers:
chrome:
gridUrl: http://chrome-node.example.com:4444/wd/hub
desiredCapabilities:
browserName: chrome
version: "45.0"
firefox:
gridUrl: http://firefox-node.example.com:4444/wd/hub
desiredCapabilities:
browserName: firefox
version: "39.0"
```
### Other configuration options
[See the details](doc/config.md) of the config file structure and available
options.
## Writing tests
Each of the blocks that are being tested may be in one of the determined states.
States are tested with the help of chains of step-by-step actions declared in a block's
test suites.
For example, let's write a test for a search block at
[yandex.com](http://www.yandex.com):
```javascript
gemini.suite('yandex-search', function(suite) {
suite.setUrl('/')
.setCaptureElements('.search2__input')
.capture('plain')
.capture('with text', function(actions, find) {
actions.sendKeys(find('.search2__input .input__control'), 'hello gemini');
});
});
```
We are creating a new test suite `yandex-search`, assuming that we will capture the
`.search2__input` element from the root URL `http://yandex.com`. We know that the
block has two states:
* `plain` — right after the page is loaded
* `with text` — with the `hello gemini` text inserted into `.search2__input .input__control`
States are executed one after another in the order in which they are defined, without the browser
reloading in between.
[See the details](doc/tests.md) of test creation methods.
## Using CLI
To complete the test creation procedure, you need to take reference shots using
the following command:
```
gemini update [paths to test suites]
```
To launch a test (to compare the current state of a block with a reference shot), use
the command:
```
gemini test [paths to test suites]
```
[See the details](doc/commands.md) of interaction with CLI and available
options.
## GUI
You can use the `Gemini` graphical user interface instead of the command line. It
is located in the [gemini-gui](https://github.com/gemini-testing/gemini-gui) package
and must be installed additionally:
```
npm install -g gemini-gui
```
GUI advantages:
* Handy preview of reference shots
* Clear real-time demonstration of the differences between a reference shot and
the current state of a block
* Easy to update reference shots
## Plugins
Gemini can be extended with plugins. You can choose from the [existing
plugins](https://www.npmjs.com/browse/keyword/gemini-plugin) or [write your
own](doc/plugins.md). To use a plugin, install and enable it in your
`.gemini.yml`:
```yaml
system:
plugins:
some-awesome-plugin:
plugin-option: value
```
## HTML report
To see the difference between the current state of a block and a reference picture
more clearly, use the [HTML reporter](https://github.com/gemini-testing/html-reporter) - plugin for gemini. This
plugin produces HTML report, which displays reference image, current image and
differences between them, for each state in each browser. When all tests are
completed, you will see a link to HTML report.
## Programmatic API
To use Gemini in your scripts or build tools, you can use the experimental
[programmatic API](doc/programmatic-api.md).
## Events
To learn more about all events in Gemini, see the [events documentation](doc/events.md).