Gherkin TestKit

A framework agnostic library for implementing Given, When, Then and parsing/validation of Gherkin feature files.

EXPERIMENTAL - DO NOT USE IN PRODUCTION

Overview

gherkin-testkit is a minimal, framework agnostic fork of jest-cucumber. Like Jest-Cucumber, it implements the Cucumber.js Gherkin AST parser. However, to keep the implementation light, gherkin-testkit does not implement a code generator used for hinting what code is needing to be implemented if missing. It is also missing the file system functionality of loadFeatures, loadFeature for compatibility with testing frameworks (such as WTR) that cannot access the filesystem using native fs calls.

Motivation

Jest-Cucumber is an excellent library for Jest which builds on top of Cucumber.js' Gherkin parser. The other alternative to Jest-Cucumber is Cucumber.js itself and Yadda, which uses its own syntax. Outside of these three libraries there are limited options. My need to work with Snowpack means I wanted to shift to Web Test Runner / RTL / Mocha / Chai / Sinon, which caused me to create this fork. Jest-Cucumber implements Jest calls in the feature-definition-creation.ts file - which is where I made function calls customizable by configuration. Without configuration, it defaults to work with Mocha's calls. Another pain problem has been Cucumber's use of profobuffjs which contains a cyclical dependency breaking both snowpack and rollup. The workaround has been to bundle this with webpack as a module.

Roadmap

If possible, it would be ideal to have a single core for both Jest and other frameworks. Currently, the plan is to implement this core (or another one like it) with a test-runner-gherkin for WTR. The same may (or may not) be done for Jest.

Example usage for WTR

The following is an example step test file:

import { readFile } from '@web/test-runner-commands';
import { parseFeature, defineFeature, getGherkinTestKitConfiguration } from 'gherkin-testkit';
import { expect } from 'chai';

//@ts-ignore
readFile({ path: './CloneInit.feature' }).then((content) => {
  const feature = parseFeature(content, getGherkinTestKitConfiguration({}));
  defineFeature(feature, test => {
    test('Valid URL given for something that exists in localStorage', ({
      given,
      when,
      then
    }) => {
      given('a user wants to load a project already in localStorage', () => {
        expect(true).to.equal(true);
      });
  
      when('the user enters a URL that matches', () => {
        expect(true).to.equal(true);
      });
  
      then('the system renders what is in localStorage', () => {
        expect(true).to.equal(true);
      });
    });
  });
});

Step file code generation

To quickly generate step files, you can use the Jest-Cucumber code generator for vscode.