CucumberJS is the one of the popular tools that supports Behaviour Driven Development (BDD). The built-in Cucumber test runner in Nightwatch is bringing the ease of writing test scripts to BDD.

The testcases in Cucumber are written as scenarios in plain language which then maps to code. This project shows some examples of Nightwatch end-to-end tests written using Cucumber.

To run the tests in the repository:

1. clone this repository: git clone https://github.com/nightwatchjs/cucumberjs-boilerplate.git
2. install the required dependencies: npm install
3. run the tests: npm test

• there are predefined cucumber steps using nightwatch commands in src/specs.
• add a feature file in tests/features using predefined steps and Gherkin syntax.
• there are some example tests in the folder to demonstrate.
• you can also use tags to filter out tests to run Eg: npm test -- --tags @nightwatch.

You can write tests in Gherkin syntax using the predefined steps from the boilerplate. There are examples under tests/featuresto demonstrate this. You can also extend this boilerplate by defining new steps under src/specs to suite your usecase.

Most of the cucumber options are picked from the Nightwatch config in order to decrease the effort while writing scripts.

{
  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: ['src/specs']
}

• feature path can be given as a string or an Array in the test runner options. All formats of feature path mentioned in Cucumber CLI are supported.

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

• With src_folders defined:

$ npx nightwatch 

• Without src_folders defined:

$ npx nightwatch src/specs

• parallel option can also be supplied as a test-runner option for cucumber.

• Parallel running using 2 workers:

$ npx nightwatch src/specs --parallel 2 

• You can use Cucumber tag expression to filter out scenarios to run. Eg: nightwatch --tags "@nightwatch and @cucumber"

• You provide in env flag in order to run test againts multiple envs(chrome, browserstack, etc). Eg: nightwatch --env chrome,firefox

• You can also use an extra setup file that can be passed as an extra --require to Nightwatch, which will be forwarded to Cucumber:

$ nightwatch src/specs --require {/full/path/to/_extra_setup.js}

• Nightwatch will also forward --format and --format-options CLI arguements, if present, to Cucumber.

• Use other test runner options as usual:

$ npx nightwatch src/specs --headless

By deafault Nightwatch uses scenario name as test name. To update more capabilities we can set auto_start_session to false in the configuration in order to prevent automatic start of the webdriver session after Nightwatch is intantiated. Nightwatch provides the instance available as this.client, which contains launchBrowser() and updateCapabilities method.

test_runner: {
  type: 'cucumber',
  options: {
    feature_path: 'test/*.feature',
    auto_start_session: false
  }
}

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

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();
});

Note: 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.

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