Comparison with Cucumber

Leftest can be thought of as a lightweight TypeScript interpretation of Gherkin syntax and Cucumber. Instead of IDE plugins it relies on type checking to get a reasonable DX with autocompletion and type checking of parameterised steps.

Gherkin feature files can be translated directly to Leftest syntax.

Gherkin

Feature: Guess the word
   Scenario: Maker starts a game
      When the Maker starts a game
      Then the Maker waits for a Breaker to join

Leftest

feature('Guess the word', () => {
   scenario('Maker starts a game', () => {
      when('the Maker starts a game')
      then('the Maker waits for a Breaker to join')
   })
})

Here's another example using scenario outline

Gherkin

Scenario Outline: eating
   Given there are <start> cucumbers
   When I eat <eat> cucumbers
   Then I should have <left> cucumbers

   Examples:
   | start | eat | left |
   |    12 |   5 |    7 |
   |    20 |   5 |   15 |

Leftest

scenario('eating', () => {
   given('there are <start> cucumbers')
   when('I eat <eat> cucumbers')
   then('I should have <left> cucumbers')

   examples([
      { start: 12, eat: 5, left: 7 },
      { start: 20, eat: 5, left: 15 },
   ])
})

IntelliJ IDEA

For the best experience with IntelliJ IDEA:

Open settings Editor > Language Injections

Disable HTML in JS Strings

If you have it installed, also disable the Cucumber.js plugin. This plugin interferes with go-to definition for steps.