Contracts That Run

A BDD runner for Vitest. Every .feature file is also a test suite: plain Given/When/Then bound to typed steps, so what the business signed is exactly what the tests measure — in watch mode and in CI.

Get Started GitHub

compas /kɔ̃·pa/ n., m. — the divider. It transfers measurements from the drawing to the work.

Renamed: vitest-bdd is now @epure/vitest.

The contract

Feature: Calculator

  Scenario: Add two numbers
    Given I have a "basic" calculator
    When I add 1 and 2
    Then the result is 3

  Scenario: Float calculator
    Given I have a "float" calculator
    When I divide 1 by 2
    Then the result is 0.5

Given("I have a {string} calculator", (name) => {
  const calculator = makeCalculator(name)

  When("I add {number} and {number}", calculator.add)

  Then("the result is {number}", (n: number) => {
    expect(calculator.result.value).toBe(n)
  })
})

$ npm install -D @epure/vitest

Why @epure/vitest

A spec nobody executes is an opinion. @epure/vitest makes every feature file a Vitest suite — what the business signed is exactly what the tests measure.

1.1

The contract reads like the domain

Plain Gherkin, compiled in memory by Vite: Given/When/Then in the language that the people who own the rules can read and sign, with no generated test file to drift.

1.2

Every scenario is a measurement

Each run steps the drawing off against the work. When reality drifts, the failure points at the exact clause: expected 3, measured 1002.

1.3

Steps are closures

Given builds the context; When and Then close over it in plain TypeScript or ReScript — no shared world, so scenarios run concurrently under Vitest.