moy-fp/test/String/headString.test.js

A functional programming library.

import __ from '../../src/Function/__'
/**
 * String -> String
 */
import headString from '../../src/String/headString'

test('headString(not using __), not empty string', () => {
  expect(
    headString('murakami')
  ).toBe('m')
})

test('headString(not using __), empty string', () => {
  expect(
    headString('')
  ).toBe('')
})

test('headString(using __), not empty string', () => {
  expect(
    headString(__)('murakami')
  ).toBe('m')
})