# Using Cucumber.js with Nightwatch 2

Nightwatch 2 brings integrated support for using [Cucumber.js](https://cucumber.io/) directly as an alternative test runner. No other plugins are necessary, other than the [Cucumber library](https://www.npmjs.com/package/@cucumber/cucumber) itself (version 7.3 or higher). 

Simply run the following in the same project where Nightwatch is also installed:

```sh
$ npm i @cucumber/cucumber --save-dev
```


## Configuration
```js
{
  test_runner: {
    // set cucumber as the runner
    type: 'cucumber',  
      
    // define cucumber specific options  
    options: {
      //set the feature path
      feature_path: 'examples/cucumber-js/*/*.feature',
      
      // start the webdriver session automatically (enabled by default)
      auto_start_session: true,
    
      // use parallel execution in Cucumber  
      parallel: 2 // set number of workers to use (can also be defined in the cli as --parallel 2
    }
  },
  
  src_folders: ['examples/cucumber-js/features/step_definitions']
}
```

## CLI Options
| option             |  description |
|------------------------|------------------------------|
| `--dry-run`        | Do all the aggregation work of looking at your feature files, loading your support code etc but without actually executing the tests. [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/dry_run.md)
| `--name`           | Specify a scenario by its name matching a regular expression. [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/cli.md#running-specific-features)    
| `--tags`             | Use tags to run specific scenario or features. [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/cli.md#tags)
| `--require`        | Use `--require <GLOB OR DIR OR FILE>` to explicitly require support files before executing the features. [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/cli.md#requiring-support-files)
| `--format`           | Use `--format <TYPE[:PATH]>` to specify the format of the output. [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/cli.md#formats)
| `--format-options`   | Many formatters, including the built-in ones, support some configurability via options. You can provide this data as a JSON literal via the --format-options CLI option. [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/formatters.md#options)         
| `--fail-fast`        | Abort the run on first failure (default: false). [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/cli.md#--fail-fast)        
| `--retries`            | Use `--retries <NUMBER-OF-ATTEMPT>` to have Cucumber attempt it multiple times until either it passes or the maximum number of attempts is reached. [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/retry.md#retry)       
| `--retry-tag-filter` |  Use `--retry-tag-filter` to retry failed scenarios based on tags. [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/retry.md#targeting-scenarios)
| `--require-module`   | [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/cli.md#transpilation)
| `--no-strict`        | By default, cucumber runner works in strict mode, meaning it will fail if there are pending steps.         
| `--parallel`         | Use `--parallel <NUMBER-OF-WORKER-THREADS>` to run your scenarios in parallel. [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/parallel.md#parallel)               
| `--profile`          | As of now only `cucumber.js` is considered while picking up profiles. [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/profiles.md)        
| `--world-parameters` | Provide this data as a JSON literal via the `--world-parameters`. [read more](https://github.com/cucumber/cucumber-js/blob/main/docs/support_files/world.md#world-parameters)


## Running
Cucumber spec files/step definition files can be provided in `src_folders` in Nightwatch config or as a CLI argument.

With `src_folders` defined:

```sh
$ npx nightwatch 
```

Without `src_folders` defined:

```sh
$ npx nightwatch examples/cucumber-js/features/step_definitions 
```

Parallel running using 2 workers:

```sh
$ nightwatch examples/cucumber-js/features/step_definitions --parallel 2 
```

Use other [test runner options](https://nightwatchjs.org/guide/running-tests/command-line-options.html) as usual:

```sh
$ npx nightwatch examples/cucumber-js/features/step_definitions --headless
```

## Disable the automatic session start
You might need sometimes to not start the Webdriver session automatically after Nightwatch is instantiated. For this purpose, Nightwatch provides the instance available as `this.client`, which contains an `launchBrowser()` method.

### Configuration:
```js
test_runner: {
  type: 'cucumber',
  options: {
    feature_path: 'examples/cucumber-js/*/*.feature',
    auto_start_session: false
  }
}
```

You can then use an extra setup file that you can pass as an extra `--require` to Nightwatch, which will be forwarded to Cucumber. In the extra setup file, you can add other operations needed to be executed before the session is started.

#### Example _extra_setup.js:

Remember to set the `browser` on `this` so it can be closed automatically by Nightwatch. Otherwise, remember to call `.quit()` in your own Cucumber `After()` hooks. 

```js
const {Before} = require('@cucumber/cucumber');

Before(async function(testCase) {
  if (!this.client) {
    console.error('Nightwatch instance was not created.');

    return;
  }

  this.client.updateCapabilities({
    testCap: 'testing'
  });

  this.browser = await this.client.launchBrowser();
});
```

#### Nightwatch setup file for Cucumber

You might also want to inspect the built-in setup file that Nightwatch uses for initializing the Cucumber runner. It is available in our project root folder at [/cucumber-js/_setup_cucumber_runner.js](https://github.com/nightwatchjs/nightwatch/blob/v2/cucumber-js/_setup_cucumber_runner.js).

#### Run with extra setup:

```sh
$ nightwatch examples/cucumber-js/features/step_definitions --require {/full/path/to/_extra_setup.js}
```

## Reporting
When using the integrated Cucumber test runner, you need to use the Cucumber [formatters](https://github.com/cucumber/cucumber-js/blob/main/docs/formatters.md) for generating output.

Nightwatch reporters (like JUnit XML reports or the [global custom reporter](https://nightwatchjs.org/guide/extending-nightwatch/custom-reporter.html)) are not available. The main reason is that reporting is delegated to the Cucumber CLI. You can also [write your own](https://github.com/cucumber/cucumber-js/blob/main/docs/custom_formatters.md) Cucumber formatter.

Nightwatch will forward `--format` and `--format-options` CLI arguments, if present, to Cucumber.

By default, the `progress` formatter is used. Here's how the output looks like when running the example tests in Firefox:

```sh
ℹ Connected to GeckoDriver on port 4444 (1740ms).
Using: firefox (92.0.1) on MAC (20.6.0).

..  ✔ Testing if the page title equals 'Rijksmuseum Amsterdam, home of the Dutch masters' (4ms)
.  ✔ Element <#rijksmuseum-app> was visible after 46 milliseconds.
.  ✔ Testing if element <.search-results> contains text 'Operation Night Watch' (1994ms)
...  ✔ Testing if the page title equals 'Rijksmuseum Amsterdam, home of the Dutch masters' (8ms)
.  ✔ Element <#rijksmuseum-app> was visible after 49 milliseconds.
.  ✔ Testing if element <.search-results> contains text 'The Night Watch, Rembrandt van Rijn, 1642' (1427ms)
.

2 scenarios (2 passed)
10 steps (10 passed)
0m13.024s (executing steps: 0m12.998s)
```