gherkin

What is gherkin?

The gherkin npm package is a parser for the Gherkin language, which is used to write structured tests in a business-readable, domain-specific language. It is commonly used in Behavior-Driven Development (BDD) frameworks like Cucumber.

What are gherkin's main functionalities?

Parsing Gherkin Syntax

This feature allows you to parse Gherkin syntax into a structured format. The code sample demonstrates how to parse a simple Gherkin feature file and output the resulting JSON structure.

const { Parser } = require('gherkin');
const parser = new Parser();
const gherkinDocument = parser.parse(`
Feature: Example feature
  Scenario: Example scenario
    Given a precondition
    When an action is performed
    Then an outcome is expected
`);
console.log(JSON.stringify(gherkinDocument, null, 2));

Tokenizing Gherkin Syntax

This feature allows you to tokenize Gherkin syntax, breaking it down into individual tokens. The code sample demonstrates how to read and print tokens from a Gherkin feature file.

const { TokenScanner, TokenMatcher, GherkinLine, Token } = require('gherkin');
const scanner = new TokenScanner(`
Feature: Example feature
  Scenario: Example scenario
    Given a precondition
    When an action is performed
    Then an outcome is expected
`);
const matcher = new TokenMatcher();
let token;
while ((token = scanner.read()) && token.isEOF === false) {
  console.log(token);
}

Generating Pickles

This feature allows you to generate 'pickles' from Gherkin documents. Pickles are a simplified, executable representation of Gherkin scenarios. The code sample demonstrates how to parse a Gherkin document and compile it into pickles.

const { Parser, Compiler } = require('gherkin');
const parser = new Parser();
const compiler = new Compiler();
const gherkinDocument = parser.parse(`
Feature: Example feature
  Scenario: Example scenario
    Given a precondition
    When an action is performed
    Then an outcome is expected
`);
const pickles = compiler.compile(gherkinDocument);
console.log(JSON.stringify(pickles, null, 2));

Other packages similar to gherkin

cucumber

Cucumber is a tool for running automated tests written in plain language. It supports the Gherkin syntax and integrates with various programming languages. Compared to gherkin, Cucumber provides a full-fledged testing framework, including test execution and reporting.

README

Gherkin parser/compiler for JavaScript. Please see Gherkin for details.

Usage

const gherkin = require('gherkin')

const options = {
  includeSource: true,
  includeGherkinDocument: true,
  includePickles: true,
}
const stream = gherkin.fromPaths(['features/hello.feature'])

// Pipe the stream to another stream that can read messages.
stream.pipe(...)