Jest Boilerplate framework: Unit tests using Jest for each functions or unit of code

App overview

A calculator that determines the cost of bookings. A booking is the time worked between a provider and consumer.

The application should read a collection of bookings from a provided JSON file, calculate the cost of each booking and write the result to a new file.

Setup and running in local machine

npm init -y to install package dependencies npm start to run app (calculator.js) npm test to run unit tests (calculator.test.js) npx jest --coverage to see code coverage (report is generated in coverage folder)

Input

The file input.json contains a collection of bookings. Each booking has an id, a from datetime and to datetime:

[
  {
    "id": 1,
    "from": "2017-10-23T08:00:00+11:00",
    "to": "2017-10-23T11:00:00+11:00"
  },
  {
    "id": 2,
    "from": "2017-10-20T09:00:00+11:00",
    "to": "2017-10-20T11:45:00+11:00"
  }
]

Business rules

Hourly rates

The rules to calculate the hourly rate of a booking are summarised below:

Rate Type	From	To	Rate ($)
Day	0600	2000	38
Night	2000	0600	42.93
Sat	All day	All day	45.91
Sun	All day	All day	60.85

Rules

• The minimum booking time is 1 hour
• The maximum booking time is 24 hours
• A booking cannot end before it has started
• A booking can be booked in 15 min increments e.g. 1600 to 1715
• If any part of a booking is charged at the night rate, the whole booking is charged at the night rate:
  • Fri 1800 - 2100 will be charged at the night rate (3 x 42.93)
  • Wed 0500 - 1000 will be charged at the night rate (5 x 42.93)
• Saturday and Sunday rates apply across the whole day, there's no distinction between day and night:
  • Sat 1800 - 2200 will be charged at the sat rate (4 x 45.91)
  • Sun 0100 - 0700 will be charged at the sun rate (6 x 60.85)

Output

The application should create a file called output.json containing the array of booking objects with total and isValid properties added. If the booking breaks one of the business rules, the total should be set to 0 and the isValid flag marked false.

[
  {
    "id": 1,
    "from": "2017-10-23T08:00:00+11:00",
    "to": "2017-10-23T11:00:00+11:00",
    "isValid": true,
    "total": 114
  },
  {
    "id": 2,
    "from": "2017-10-20T09:00:00+11:00",
    "to": "2017-10-20T11:45:00+11:00" ,
    "isValid": true,
    "total": 104.50
  },
]

The expected output can be found in expectedOutput.json