This is simple payment gateway API with basic functionality of handling transactions.
- API for processing of authorize/charge/refund/reversal transactions
- UI for manage merchants.
Transaction Logic
- Each payment request/attempt is stored even if it failed. If payment processing fails it stored and marked with :error. Ideally it must be done in a separate model, e.g. PaymentRequest, but it is out of scope of the task.
- Authorize can have only one full charge. Second charge or partial charge is not allowed.
- Charge can have multiple refunds. Total refunds must not exceed total charge amount.
Admin UI
- Create/Update/Destroy merchants
- Inspect merchant transactions
Merchant UI
- Inspect own transactions
Business logic is decoupled from Rails application and placed in app/concepts
folder. It is build with:
- Use Cases are used to handle all user-related operations. It implements Interactor pattern (not gem).
- Form Objects are used to validate user's input.
- Presenters (View Models) are used to expose and shape data for presentation layer.
- Service Object are used to process business logic of payments.
- Policies are used to handle permissions
STI used for Transactions classes
Frontend is implemented using bootstrap, webpacker
Scheduled (cron) jobs is implemented using clockwork gem
States are implemented with simple enums. It is enough for the purpose of tasks, so State Machine was not used.
- Business logic has near 100% unit test coverage.
- Rails application has lower coverage and can be improved.
- RSpec is used for testing.
- Capybara is used for feature testing.
- SimpleCove is used for calculating test coverage. Run full test suites (
rspec
) and opencoverage/index.html
.
- Main focus was on the application core, rather than proper setting up environment and dependencies.
- Commits organized in "features" i.e. one commit per feature. It is done for easier review in one go, since the application is quite big. Each feature-commit has description which approximately reflects atomic smaller commits in real project.
- One dev environment is tested. The source code is as production-ready as possible, though application might need few more steps to properly run in production environment.
- TODO.md has the list of some remaining steps to do
Application was developed and tested with following environment
- PostgreSQL 13.0
- ruby 2.7.1
- nodejs 14.14.0
- yarn 1.22.5
docker-compose.yml
configured to run PostgreSQL and expose 55555 port to localhost.
bundle install
docker-compose up
bundle exec rake db:create db:migrate db:seed
bundle exec rake import_merchants\['db/seeds/merchants.csv'\]
PORT=3000 foreman start
Go to https://localhost:3000/admins/merchants
Use credentials [email protected] / 123456
from seeds/admins.rb
Go to https://localhost:3000/merchants/transactions
Use credentials [email protected] / 12345678
from seeds/merchants.csv
- Get token
curl \
-X POST https://localhost:3000/api/v1/auth/sign_in \
-D - \
-d "[email protected]" \
-d "password=12345678"
Take headers for next API requests
access-token
client
uid
- Submit Payment
Make sure uuid
is unique for each request. Each uuid
can be used once and only once.
curl \
-X POST https://localhost:3000/api/v1/payments \
-H 'client: 14PmhzFUXujhA4QrOabeVw' \
-H 'access-token: rvmCH6gdTG4LmAqHUfYLBA' \
-H 'uid: [email protected]' \
-F "type=authorize" \
-F "uuid=3" \
-F "amount=50" \
-F "[email protected]"
- For charge/reverse add
-F "authorize=:authorizeId"
, where:authorizeId
isuuid
to existing authorize - For refund add
-F "charge=:chargeId"
, where:chargeId
isuuid
to existing charge