Testing utility functions
Let's test our code now! Let's start with utils. Create a file called utils.spec.js and import the leftPad function:
import { leftPad } from '~/utils/utils'Have a look at this function again:
// utils/utils.js
export const leftPad = value => {
if (('' + value).length > 1) {
return value
}
return '0' + value
}This function should return the input string if this string's length is greater than 1. If the string's length is 1, it should return the string with a preceding 0.
Seems quite easy to test it, right? We would write two test cases:
// test/utils.spec.js
describe('utils', () => {
describe('leftPad', () => {
it('should return the string itself if its length is more than 1', () => {
expect(leftPad('01')).toEqual('01')
})
it('should add a 0 from the left if the entry string is of the length of 1', () => {
expect(leftPad('0')).toEqual('00')
})
})
})Argh...if you run this test, you will get an error:
Of course...