Payment processing gateway implementation.

To start the application in a Docker container run the following command from the root directory:

docker-compose up

When the docker container is running, the API will be available on http://localhost:5000/.

Note: The implemented bank stub will decline all EUR payments and any GBP payments over £1000.

Payment Gateway controller has been implemented to validate the payment requests and fail fast if any fields in the payment request fail validation.

The follwing APIs have been implemented:

POST - api/v1/paymentgateway/processpayment

This API should be called with a JSON body containing the following fields (with example values):

{
    "cardNumber": "1234123412341234",
    "cardExpirationDate": "12/2021",
    "cardVerificationValue": "123",
    "cardHolderName": "Patryk Szczerbinski",
    "amount": 500,
    "currency": "GBP"
}

GET - api/v1/paymentgateway/retrievepayment/{identifier}

This API retrieves details of payment process requests made using the processpayment API. The identifier should be the payment identifier from the response of the processpayment API.

Unit test have been included in the PaymentGateway.Tests project and can be run from the solution directory using the following command or from within Visual Studio.

dotnet test PaymentGateway.Tests/PaymentGateway.Tests.csproj

The integration tests have been implemented to simulate the user using the API. The tests are using a simple PaymentGatewayApi class that uses the HttpClient to call the REST API of the Payment Gateway.

Once the docker container is running, the integration tests can be run from the solution directory using the following command.

dotnet test PaymentGateway.IntegrationTests/PaymentGateway.IntegrationTests.csproj --settings PaymentGateway.IntegrationTests/IntegrationTestSettings.runsettings

The IntegrationTestSettings.runsettings file contains the address of where the gateway is located so it can be changed if the container is running in the cloud.

For this solution, I have implemented MongoDB storage for the payments. The storage will persist for the lifetime of the MongoDB container.

Database administration tools are available via Mongo Express at http://localhost:8081/.

• Username: dev
• Password: devpassword

• Support for AMEX cards, which have a 4 digit CVV
• Addition of a billing address in the payment request
• Validation in the bank stub layer
• Better type for transaction amount to avoid double precision issues
• Implement tests around the Mongo implementation
• Improve code security by hiding sensitive data in a vault