GraphQL Aptitude Test For Buy Coins

You're going to create a GraphQL API with one query. The query calculatePrice will accept three required arguments:

• type: This can either be buy or sell, nothing else.
• margin: This is a percentage that will be used in a calculation. Not a fraction, a percentage. For example, if 0.2 is passed into this argument, then the calculation should be done with 0.2%.
• exchangeRate: This is a custom USD/NGN exchange rate that will be used in the calculation detailed below.

• When calculatePrice is called, your API must make a request to Coindesk's API to retrieve the current price of Bitcoin in USD.
• If the type is sell, then your API should subtract the computed value of the margin percentage from the current Bitcoin price it just retrieved.
• If the type is buy, then your API should add the computed value of the margin percentage to the current Bitcoin price it just retrieved.
• Finally, the number calculatePrice responds will be in NGN and not USD. This should be calculated using the exchangeRate argument.

• Query: query calculatePrice($type:String!, $margin: Float!, $exchangeRate: String!) { calculatePrice(type: $type, margin: $margin, exchangeRate: $exchangeRate){ price, currency, type } }

• Query Variables: { "type": "sell", "margin": 0.2, "exchangeRate": "USD" }