Ideal unit test (https://medium.com/javascript-scene/what-every-unit-test-needs-f6cd34d9836d)

unit.test.js

test('What component aspect are you testing?', assert => {
  const message = 'What should the feature do?'
  
  const actual = 'What is the actual output?'
  const expected = 'What is the expected output?'

  assert.equal(actual, expected, message)
})

// examples
const double = i => i * 2

test('Double given 2', assert => {
  const message = 'Should return 4'
  
  const actual = double(2)
  const expected = 4

  assert.equal(actual, expected, message)
})