di vitest kita bisa menggunakan jest atau chai.

kita bisa jalankan npx vitest, untuk watch mode jika ada perubahan pada file tidak perlu running ulang test lagi.

Test Filtering

skip

jika kita menambahkan skip pada describe, maka semua test didalamnya tidak akan dijalankan

describe.skip('skipped suite', () => {
  it('test', () => {
    // Suite skipped, no error
    assert.equal(Math.sqrt(4), 3)
  })
  it('1 + 1', () => {
    assert.equal(1 + 1, 2)
  })
})

test yang dijalankan hanya yang tidak menggunakan .skip

describe('suite', () => {
  it.skip('skipped test', () => {
    // Test skipped, no error
    assert.equal(Math.sqrt(4), 3)
  })
  it('1 + 1', () => {
    assert.equal(1 + 1, 2)
  })
})

only

jika kita menambahkan only pada describe atau test/it di suatu file, maka test yang dijalankan hanya yang menggunakan .only saja, yang lainnya di skip.

describe.only('.only pada describe', () => {
  it('test', () => {
    assert.equal(Math.sqrt(4), 2)
  })
})

describe('.only pada test/it', () => {
  it('skipped test', () => {
    // Test skipped, as tests are running in Only mode
    assert.equal(Math.sqrt(4), 3)
  })

  it.only('test', () => {
    // Only this test (and others marked with only) are run
    assert.equal(Math.sqrt(4), 2)
  })
})

Matcher pada jest

Matcher Umum

toBe() = untuk cek nilai hasil dari expect(2 + 2).

test('2 + 2 = 4', () => {
  expect(2 + 2).toBe(4)
})

not.toBe() = untuk cek nilai hasil dari expect(1 + 2)

test('1 + 2 != 2', () => {
  expect(sum(1, 2)).not.toBe(2)
})

toEqual() = untuk cek nilai biasa ataupun object

test('2 + 2 = 4', () => {
  expect(2 + 2).toEqual(4)
})

test('cek object', () => {
  const data = { one: 1 }
  data['two'] = 2
  expect(data).toEqual({ one: 1, two: 2 })
})

Matcher Truthiness (untuk cek hasil bernilai true atau false)

test('cek nilai null', () => {
  const n = null
  expect(z).not.toBeNull() // false
  expect(n).toBeNull() // true
  expect(n).toBeDefined() // true
  expect(n).not.toBeUndefined() // true
  expect(n).not.toBeTruthy() // true
  expect(n).toBeFalsy() // true
})

test('cek nilai 0', () => {
  const z = 0
  expect(n).toBeNull() // false
  expect(z).not.toBeNull() // true
  expect(z).toBeDefined() // true
  expect(z).not.toBeUndefined() // true
  expect(z).not.toBeTruthy() // true
  expect(z).toBeFalsy() // true
})

Matcher Numbers

test('2 + 2', () => {
  const value = 2 + 2
  expect(value).toBeGreaterThan(3)
  expect(value).toBeGreaterThanOrEqual(3.5)
  expect(value).toBeLessThan(5)
  expect(value).toBeLessThanOrEqual(4.5)

  // toBe and toEqual are equivalent for numbers
  expect(value).toBe(4)
  expect(value).toEqual(4)
})

untuk floating number bisa gunakan toBeCloseTo

test('adding floating point numbers', () => {
  const value = 0.1 + 0.2
  //expect(value).toBe(0.3);           This won't work because of rounding error
  expect(value).toBeCloseTo(0.3) // This works.
})

Matcher string

describe('matcher string', () => {
  test('there is no I in team', () => {
    expect('team').not.toMatch(/I/)
  })

  it('but there is a "stop" in Christoph', () => {
    expect('Christoph').toMatch(/stoph/)
  })
})

Matcher array

const shoppingList = ['diapers', 'kleenex', 'trash bags', 'paper towels', 'milk']

test('the shopping list has milk on it', () => {
  expect(shoppingList).toContain('milk')
  expect(new Set(shoppingList)).toContain('milk')
})

Matcher exception

function compileAndroidCode() {
  throw new Error('you are using the wrong JDK!')
}

test('compiling android goes as expected', () => {
  expect(() => compileAndroidCode()).toThrow()
  expect(() => compileAndroidCode()).toThrow(Error)

  // You can also use a string that must be contained in the error message or a regexp
  expect(() => compileAndroidCode()).toThrow('you are using the wrong JDK')
  expect(() => compileAndroidCode()).toThrow(/JDK/)

  // Or you can match an exact error message using a regexp like below
  expect(() => compileAndroidCode()).toThrow(/^you are using the wrong JDK$/) // Test fails
  expect(() => compileAndroidCode()).toThrow(/^you are using the wrong JDK!$/) // Test pass
})

Lengkapnya bisa cek disini https://jestjs.io/docs/expect

Menggunakan assert milik chai

chai memiliki 2 style, kita bisa menggunakan gaya expect, atau menggunakan assert.

import { assert, describe, it } from 'vitest'

describe('chai', () => {
  it('test', () => {
    assert.isOk(true, 'everything is ok')
    // assert.isOk(false, 'this will fail')
    assert.equal('3', '3', '== coerces values to strings')
    assert.deepEqual({ tea: 'green' }, { tea: 'green' }) // cek object
  })
})

Lengkapnya bisa cek disini https://www.chaijs.com/api/assert/

Test secara parallel dengan concurrent

dua unit akan di jalankan bersamaan, jika yang menggunakan concurrent hanya pertama dan ketiga, maka concurrent tidak jalan

describe('suite', () => {
  it('serial test 1', async () => {
    await new Promise((resolve) => {
      setTimeout(resolve, 3000)
    })
    expect(1).toBe(1)
  })
  it.concurrent('serial test 2', async () => {
    await new Promise((resolve) => {
      setTimeout(resolve, 1000)
    })
    expect(1).toBe(1)
  })
  it.concurrent('serial test 3', async () => {
    await new Promise((resolve) => {
      setTimeout(resolve, 2000)
    })
    expect(1).toBe(1)
  })
})

jika kita ingin semua unit bisa berjalan secara parallel, kita bisa menambahkan .concurrent cukup di describe nya. lihat kode dibawah

describe.concurrent('suite', () => {
  it('serial test 1', async () => {
    await new Promise((resolve) => {
      setTimeout(resolve, 3000)
    })
    expect(1).toBe(1)
  })
  it('serial test 2', async () => {
    await new Promise((resolve) => {
      setTimeout(resolve, 1000)
    })
    expect(1).toBe(1)
  })
  it('serial test 3', async () => {
    await new Promise((resolve) => {
      setTimeout(resolve, 2000)
    })
    expect(1).toBe(1)
  })
})