react-common/lib/services/splitValueAndUnit.test.ts

import * as fc from 'fast-check'
import splitValueAndUnit, { Unit } from './splitValueAndUnit'

it('should exist', () => {
  expect(splitValueAndUnit).toBeDefined()
})

it('should be a function', () => {
  expect(splitValueAndUnit).toBeFunction()
})

it('should accept 1 argument', () => {
  expect(splitValueAndUnit).toHaveLength(1)
})

it('should throw a TypeError when invalid values are supplied', () => {
  fc.assert(
    fc.property(fc.anything().filter((s) => !['string', 'number'].includes(typeof s)), (s) => {
      expect(() => splitValueAndUnit(s)).toThrowError(TypeError)
    }),
  )
})

it('should parse valid CSS numbers', () => {
  fc.assert(
    fc.property(
      fc.tuple(fc.float(), fc.oneof<Unit>(fc.constant('px'), fc.constant('rem'), fc.constant('%'))),
      ([magnitude, unit]) => {
        expect(splitValueAndUnit(`${magnitude}${unit}`)).toEqual({
          magnitude,
          unit,
        })
      },
    ),
  )
})

it('should parse numbers as CSS numbers with implicit pixel units', () => {
  fc.assert(
    fc.property(fc.float(), (magnitude) => {
      expect(splitValueAndUnit(magnitude)).toEqual({
        magnitude,
        unit: 'px',
      })
    }),
  )
})