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',
        })
      }
    )
  )
})