konnorandrews / jest-bdd

Behavior-driven development wrapper for Jest

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

jest-bdd's Issues

Fail then when when fails

If a when fails, I feel like the then following it should simply not run, i.e. when is the precondition, if that isn't satisfied, then the code simply should not execute. Any tips on how to achieve this?