gherkin-lint

What is gherkin-lint?

The gherkin-lint npm package is a linter for Gherkin files, which are used in Behavior-Driven Development (BDD) to describe software behaviors in a natural language format. The tool helps ensure that Gherkin files adhere to best practices and style guidelines, making them easier to read and maintain.

What are gherkin-lint's main functionalities?

Linting Gherkin Files

This feature allows you to lint Gherkin files to ensure they follow specified rules. The code sample demonstrates how to use gherkin-lint to check for empty scenarios in a Gherkin file.

const gherkinLint = require('gherkin-lint');
const config = { 'no-empty-scenarios': 'error' };
const results = gherkinLint.lint(['path/to/feature/file.feature'], config);
console.log(results);

Custom Rule Configuration

This feature allows you to configure custom rules for linting. The code sample shows how to set up multiple rules, such as checking for empty scenarios and duplicate feature names.

const gherkinLint = require('gherkin-lint');
const config = {
  'no-empty-scenarios': 'error',
  'no-dupe-feature-names': 'warn'
};
const results = gherkinLint.lint(['path/to/feature/file.feature'], config);
console.log(results);

Command Line Interface

The gherkin-lint package also provides a command-line interface for linting Gherkin files. The code sample demonstrates how to use the CLI with a configuration file.

npx gherkin-lint -c path/to/config.json path/to/feature/file.feature

Other packages similar to gherkin-lint

cucumber

Cucumber is a tool for running automated tests written in plain language. While it is primarily focused on executing tests, it also includes some linting capabilities for Gherkin files. However, its primary focus is on test execution rather than linting.

gherkin

The gherkin package is a parser for Gherkin language. It focuses on parsing and tokenizing Gherkin files rather than linting them. It can be used as a building block for creating custom linters or other tools that work with Gherkin files.

README

Gherkin lint

Uses Gherkin to parse feature files and runs linting against the default rules, and the optional rules you specified in your .gherkin-lintrc file.

Installation

npm install gherkin-lint

Demo

To see the output for all the errors that the linter can detect run:

git clone https://github.com/vsiakka/gherkin-lint.git
npm run demo

Or check this:

Available rules

Name	Functionality
no-tags-on-backgrounds *	Disallows tags on Background
one-feature-per-file *	Disallows multiple Feature definitions in the same file
up-to-one-background-per-file *	Disallows multiple Background definition in the same file
no-multiline-steps *	Disallows mutiline Steps
no-examples-in-scenarios	Disallow the use of "Examples" in scenarios
allowed-tags	Just the listed tags are allowed
indentation	Allows the user to specify indentation rules
name-length	Allows restricting length of Feature/Scenario/Step names
new-line-at-eof	Disallows/enforces new line at EOF
no-background-only-scenario	Disallows background when there is just one scenario
no-dupe-feature-names	Disallows duplicate Feature names
no-dupe-scenario-names	Disallows duplicate Scenario names
no-duplicate-tags	Disallows duplicate tags on the same Feature or Scenario
no-empty-background	Disallows features with backgrounds without steps
no-empty-file	Disallows empty feature files
no-files-without-scenarios	Disallows files with no scenarios
no-homogenous-tags	Disallows tags present on every Scenario in a Feature, rather than on the Feature itself
no-multiple-empty-lines	Disallows multiple empty lines
no-partially-commented-tag-lines	Disallows partially commented tag lines
no-restricted-tags	Disallow use of particular @tags
no-scenario-outlines-without-examples	Disallows scenario outlines without examples
no-superfluous-tags	Disallows tags present on a Feature and a Scenario in that Feature
no-trailing-spaces	Disallows trailing spaces
no-unnamed-features	Disallows empty Feature name
no-unnamed-scenarios	Disallows empty Scenario name
no-unused-variables	Disallows unused variables in scenario outlines
one-space-between-tags	Tags on the same time must be separated by a single space
use-and	Disallows repeated step names requiring use of And instead

* These rules cannot be turned off because they detect undocumented cucumber functionality that causes the gherkin parser to crash.

Rule Configuration

The not-configurable rules are turned on by default and cannot be turned off. Configurable rules can be customized using a file.

The configurable rules are off by default. To turn them on, you will need to create a json file, where you specify the name of each rule and its desired state (which can be "on" or "off"). Eg:

{
  "no-unnamed-features": "on"
}

will turn on the no-unnamed-features rule.

allowed-tags

allowed-tags must be configured with list of tags for it to have any effect:

{
  "allowed-tags": ["on", {"tags": ["@watch", "@wip", "@todo"]}]
}

Any tag not included in this list won't be allowed.

indentation

indentation can be configured in a more granular level and uses following rules by default:

• Expected indentation for Feature, Background, Scenario, Examples heading: 0 spaces
• Expected indentation for Steps and each example: 2 spaces

You can override the defaults for indentation like this:

{
  "indentation" : [
    "on", {
      "Feature": 0,
      "Background": 0,
      "Scenario": 0,
      "Step": 2,
      "Examples": 0,
      "example": 2,
      "given": 2,
      "when": 2,
      "then": 2,
      "and": 2,
      "but": 2,
      "feature tag": 0,
      "scenario tag": 0
    }
  ]
}
There is no need to override all the defaults, as is done above, instead they can be overriden only where required.  `Step` will be used as a fallback if the keyword of the step, eg. 'given', is not specified.  If `feature tag` is not set then `Feature` is used as a fallback, and if `scenario tag` is not set then `Scenario` is used as a fallback.

This feature is able to handle all localizations of the gherkin steps.

name-length

name-length can be configured separately for Feature, Scenario and Step names. The default is 70 characters for each of these:

{
  "name-length" : ["on", { "Feature": 70, "Scenario": 70, "Step": 70 }]
}

new-line-at-eof

new-line-at-eof can also be configured to enforcing or disallowing new lines at EOF.

• To enforce new lines at EOF:

{
  "new-line-at-eof": ["on", "yes"]
}

• To disallow new lines at EOF:

{
  "new-line-at-eof": ["on", "no"]
}

no-restricted-tags

no-restricted-tags must be configured with list of tags for it to have any effect:

{
  "no-restricted-tags": ["on", {"tags": ["@watch", "@wip", "@todo"]}]
}

Configuration File

The default name for the configuration file is .gherkin-lintrc and it's expected to be in your working directory.

If you are using a file with a different name or a file in a different folder, you will need to specify the -c or --config option and pass in the relative path to your configuration file. Eg: gherkin-lint -c path/to/configuration/file.extention

You can find an example configuration file, that turns on all of the rules in the root of this repo (.gherkin-lintrc).

Ignoring Feature Files

There are 2 ways you can specify files that the linter should ignore:

1. Add a .gherkin-lintignore file in your working directory and specify one glob pattern per file line
2. Use the command line option-i or --ignore, pass in a comma separated list of glob patterns. If specified, the command line option will override the .gherkin-lintignore file.

Custom rules

You can specify one more more custom rules directories by using the -r or --rulesdir command line option. Rules in the given directories will be available additionally to the default rules.

Example:

gherkin-lint --rulesdir "/path/to/my/rulesdir" --rulesdir "from/cwd/rulesdir"

Paths can either be absolute or relative to the current working directory. Have a look at the src/rules/ directory for examples; The no-empty-file rule is a good example to start with.