artillery/docs/engines.md

Flexible and powerful toolkit for load and functional testing

# Writing an Artillery engine

Artillery has an engine interface. An engine can be used by artillery to execute requests using protocols that are not supported out-of-the-box.

## Writing an engine
#### Naming
Your engine's node package name should follow the convention of `artillery-engine-[engine name]`.

#### Files
Only 2 files are required: `package.json` and `index.js`.

#### `index.js`
The engine's `index.js` file should export a single default object.

Object is expected to have a method named `createScenario`, which will be called by artillery each time scenario is executed, will receive the scenario's configuration and is expected to return a function that internally executes all logic in scenario.

##### Example for minimal `index.js` implementation:
```
function MyNewEngine(script, ee, helpers) {
    this.script = script;
    this.ee = ee;
    this.helpers = helpers;

    return this;
}

MyNewEngine.prototype.createScenario = function createScenario(scenarioSpec, ee) {
    function executeMyScenario() {
        ee.emit('started');
        ee.emit('done');
    };
    return executeMyScenario;
};

module.exports = MyNewEngine;
```

This is of course very minimal. The scenario spec typically includes a flow in it, and it is up to you as the developer to return a function that executes the full flow listed in the configuration, using your chosen protocol.