assoc.spec.js

import { assoc } from './assoc.js'

test('adds a key to an empty object', () => {
  expect(assoc(
    'a', 1, {}
  )).toEqual({ a : 1 })
})

test('adds a key to a non-empty object', () => {
  expect(assoc(
    'b', 2, { a : 1 }
  )).toEqual({
    a : 1,
    b : 2,
  })
})

test('adds a key to a non-empty object - curry case 1', () => {
  expect(assoc('b', 2)({ a : 1 })).toEqual({
    a : 1,
    b : 2,
  })
})

test('adds a key to a non-empty object - curry case 2', () => {
  expect(assoc('b')(2, { a : 1 })).toEqual({
    a : 1,
    b : 2,
  })
})

test('adds a key to a non-empty object - curry case 3', () => {
  const result = assoc('b')(2)({ a : 1 })

  expect(result).toEqual({
    a : 1,
    b : 2,
  })
})

test('changes an existing key', () => {
  expect(assoc(
    'a', 2, { a : 1 }
  )).toEqual({ a : 2 })
})

test('undefined is considered an empty object', () => {
  expect(assoc(
    'a', 1, undefined
  )).toEqual({ a : 1 })
})

test('null is considered an empty object', () => {
  expect(assoc(
    'a', 1, null
  )).toEqual({ a : 1 })
})

test('value can be null', () => {
  expect(assoc(
    'a', null, null
  )).toEqual({ a : null })
})

test('value can be undefined', () => {
  expect(assoc(
    'a', undefined, null
  )).toEqual({ a : undefined })
})

test('assignment is shallow', () => {
  expect(assoc(
    'a', { b : 2 }, { a : { c : 3 } }
  )).toEqual({ a : { b : 2 } })
})