Welcome to the Updraft technical test. In this folder you will find a small Django web service configured with Django REST framework. We recommend reading this entire README all of the way through so that you understand the task, expectations and what has been provided for you before making a start.

⚠️ Please do not upload your solutions to public repositories on GitHub or other publicly available or indexed spaces on the internet. Doing so can allow future applicants to reference your solution and undermine the integrity of the test.

Obviously we want all current and future candidates to be on an even playing field and we don't want to have to keep writing new tests (and new assessment notes and criteria) each time we do a round of interviews. We thank you for your understanding and cooperation in this respect. 🙂

We realise this sounds like an unlikely form of plagerism to occur, but Google is powerful and trust us: this is exactly how at least one engineer at Updraft used to find the answers to their university coursework... 🤷‍♂️

Getting set up

Before getting started with the main tasks, you'll need to configure your development environment and make sure the tests pass.

1. create a python 3 virtual environment
2. install dependencies with poetry
3. run the tests

Create a Python 3 virtual environment

You will need a Python 3 venv to get started. For the purposes of this exercise, any modern Python 3 version will be fine. If you have a prefered way of managing venvs, then feel free to use that. If not, the following command will probably be enough to get you going:

python3 -m venv .venv
source .venv/bin/activate

Install Dependencies with poetry

We use poetry to manage python dependencies, if you don't have it installed globally then you can install it in your venv using pip like so:

pip install poetry

Now you can use it to install all of the dependencies:

poetry install

If you need to add a new library to the project, you can do so like this:

poetry add [--dev] <library>

This will update pyproject.toml and poetry.lock with the new dependency so that we will be able to install the same version when evaluating your solution.

Sample (fixture) data

We've provided some fixture date that will create three users:

1. a super user "test-admin" for using django admin panel
2. a normal user "user1" with two bank accounts
3. a normal user "user2" with one bank account

Each user's password is the same as their username.

To load the sample data, ensure that your venv is active and then run all of the database migrations and load the data using manage.py:

python manage.py migrate
python manage.py loaddata sample.json

Now if you run the server and browse to the admin panel (http://localhost:8000/admin) log in as "test-admin" (password is also "test-admin") you should see the three accounts and 419 sample transactions.

If you want to make use of this fixture data in any tests you write, be sure to set the fixtures property of your APITestCase subclass:

class TestSomething(APITestCase):

    fixtures = ["sample.json"]

    def test_something(self):
        # there are three accounts in the fixture data
        assert Accounts.objects.count() == 3

Run the tests

We use pytest to run our tests:

pytest

You should see all tests failing, as the endpoints that they are testing have not been implemented. As you work on your task, you may wish to add more tests to ensure that you're covering all the important scenarios.

Your task

You will need to create both list and retrieve endpoints for the Account and Transaction models.

When building these endpoints, we encourage you to develop a solution that you would consider to be clean, maintainable and uses Django REST framework's built-in tools to fullfil the requirements. This exercise is less about "just build something that works" and more "show us how you woud build this in a larger production app." Django REST framework gives you a lot of tools out of the box and we'd like you to use this as an opportunity to demonstrate your knowledge of those tools to us.

The following URLs are expected to be supported:

• GET /accounts/ - list all bank accounts
• GET /accounts/:id - retrieve the bank account with ID :id
• GET /transactions/ - list all transactions
• GET /transactions/:id - retireve the transactions with ID :id

Additionally, these endpoints should meet the following requirements:

1. Users should only be able to see their own Accounts and Transactions, whilst an admin (as defined by the User.is_staff flag) should be able to view all accounts and transactions in the system.
2. All "list" endpoints should be paginated using cursor-based pagination.
3. The Transactions list endpoint should be ordered with the most recent transactions first and allow a user to filter by:
   • a start and/or end timestamp
   • the ID of one of their accounts
   • a transaction category (see accounts.models.TransactionCategory)
4. The Account endpoints should include two fields that are not part of the normal Account model:
   • transaction_count_last_thirty_days which should be the count of all Transactions that occured on this account in the last 30 days.
   • balance_change_last_thirty_days which should be the sum of all Transactions that occurred on this account in the last 30 days.

An Account object should be represented like this when returned as part of an API response:

{
    "id": 1,
    "user": 2,
    "name": "John Smith"
    "transaction_count_last_thirty_days": 119,
    "balance_change_last_thirty_days": "-1304.67",
}

(Note: the fields that calculate values for the last thirty days will change values depending which day you actually do this test. Don't worry if yours come out different. See TestAccountsApiAsStaff::test_retrieve_account in accounts/tests.py for a way to fix this during testing with the freeze_time annotation from the freezegun package)

A Transaction object should be represented like this:

{
    "id": 1,
    "account": 1,
    "timestamp": "2022-06-12T17:36:58.632000Z",
    "amount": "-25.26",
    "description": "Tesco",
    "transaction_category": "PURCHASE"
}