Jest BDD

Behavior-driven development wrapper for Jest

Installation

npm install jest-bdd

Usage

In-line

const { unit, given, when, then } = require('jest-bdd')

unit(
  given('two numbers', () => {
    scope.num1 = 3
    scope.num2 = 8
  },
    then('num1 is 3', () => { // check the setup
      expect(num1).toBe(3)
    }),
    when('the numbers are added', () => { // perform the action to test
      scope.sum = num1 + num2
    },
      then('the sum is 11', () => { // check the result of the action
        expect(sum).toBe(11)
      })
    )
  )
)

Output:
  Given: two numbers
    ✓ Then: num1 is 3
    When: the numbers are added
      ✓ Then: the sum is 11

Rules

Rules allow reusable clauses to be created.

const { Rules, Given, when, Then, unit } = require('jest-bdd')

const rules = RuleGroup()

Given(rules.two_numbers, () => {
  scope.num1 = 3
  scope.num2 = 8
})

When(rules.the_numbers_are_added, () => {
  scope.sum = num1 + num2
})

Then(rules.num1_is_3, () => {
  expect(num1).toBe(3)
})

Then(rules.the_sum_is_11, () => {
  expect(sum).toBe(11)
})

useRules(rules, () => unit(
  given.two_numbers(
    then.num1_is_3,
    when.the_numbers_are_added(
      then.the_sum_is_11
    )
  )
))

Output:
  Given: two numbers
    ✓ Then: num1 is 3
    When: the numbers are added
      ✓ Then: the sum is 11

Tests

npm test