Smartwyre Developer Test Instructions

In the 'PaymentService.cs' file you will find a method for making a payment. At a high level the steps for making a payment are:

1. Lookup the account the payment is being made from.
2. Check that the account is in a valid state to make the payment.
3. Deduct the payment amount from the account’s balance and update the account in the database.

What we’d like you to do is refactor the code with the following things in mind:

• Adherence to SOLID principals
• Testability
• Readability

We’d also like you to

• Add some unit tests to the Smartwyre.DeveloperTest.Tests project to show how you would test the code that you’ve produced
• Run the PaymentService from the Smartwyre.DeveloperTest.Runner console application

The only specific 'rules' are:

• The solution should build
• The tests should all pass

You are free to use any frameworks/NuGet packages that you see fit. You should plan to spend around 1 hour completing the exercise.