JustGiving FinTech Test

A big part of what we do at JustGiving is reclaim the Gift Aid on donations made to charities. This saves them a lot of time and processing overheads.

The calculation for gift aid is [Donation Amount] * ( [TaxRate] / (100 - [TaxRate]) ).

• For unit testing we use NUnit and NSubstitute, these are already referenced in the projects, but feel free to use which ever framework you prefer.
• All stories should be completed with an appropriate amount of testing.
• Please create a public repo (GitHub, BitBucket, GitLab etc) and send us the link, make sure to commit regularly so we can see how you came up with the solution.
• Remember to be RESTful.

Story 1 - Gift Aid Calculator

• Create a calculator.
• Gift aid calculated at a tax rate of 20%.

Story 2 - Endpoint

• Create an endpoint so that other services can access the calculation for Gift Aid.
• Use this swagger spec as the basis for your API

swagger: '2.0'
info:
  title: Gift Aid Service
  version: 1.0.0
basePath: /api
schemes:
  - https
paths:
  /giftaid:
    get:
      summary: Get the amount of gift aid reclaimable for donation amount
      parameters:
        - in: query
          name: amount
          type: number
          required: true
      produces:
        - application/json
      responses:
        '200':
          description: OK
          schema:
            $ref: '#/definitions/GiftAidResponse'
definitions:
  GiftAidResponse:
    type: object
    required:
      - donationAmount
      - giftAidAmount
    properties:
      donationAmount:
        type: number
      giftAidAmount: 
        type: number

Story 3 - Validation

• There are two validation rules:
  • Minimum donation amount is £2.00.
  • Maximum donation amount is £100,000.00.
• Add validation for these cases and any other validation / error handling you think is appropriate for this endpoint.
• Add appropriate tests and document the endpoint

Story 4 - Storing Gift Aid Declarations

• When a user makes a donation with Gift Aid, we need to store information about the donor.
• We need to store:
  • Name
  • Post Code
  • Donation Amount
• Add an endpoint for this.
• Mock a database or add a simple in-memory database (maybe LiteDB) to persist this data.
• Produce a unique id for the declaration.
• Return the declaration id and the gift aid amount in the reponse.
• Add appropriate tests and document the endpoint

Thanks for your time, we look forward to hearing from you!