capitalone-exercise

The capitalone package and its command line interface capitalone.py were developed and tested under Python 3.6 on macOS Sierra. The source is mypy 0.511 clean.

The command line interface is self documenting. Assuming that the Python 3.6 interpreter is on your path, run this command from the capitalone-exercise directory to get help:

python3.6 capitalone.py --help

Tests that run each of the examples in the next section are provided. The tests run against live data. Time to write mocks (see, for example requests-mock) against a stable source of transactions. We did check in such a such a source: tests/Transactions.json but do not use it.

Given the nature of this exercise it is worth noting that income and expense averages are computed using Python's decimal package and its default context:

>>> from decimal import *
>>> getcontext()
Context(
    prec=28, rounding=ROUND_HALF_EVEN, Emin=-999999, Emax=999999, capitals=1, clamp=0, flags=[], traps=[
        InvalidOperation, DivisionByZero, Overflow
    ]
)

Results were checked against the numbers produced by Microsoft Excel for Mac version 15.33 and we saw some differences in the second decimal place on averages. If we were to take this exercise one more step we might reconcile those differences taking Capital One's rounding rules into account.

Issue these commands to run tests against live data:

cd tests && python3.6 -m pytest .

Examples

Example 1:

Produce unfiltered income and expense report.

python3.6 capitalone.py --email interview@levelmoney.com --password password2

Output:

A single JSON document of income and expenses as documented in Coding-exercise-instructions.md.

Example 2:

Produce income and expense report that excludes expenses (or--theoretically--income earned) on donuts.

python3.6 capitalone.py --email interview@levelmoney.com --password password2 --ignore-donuts

Output:

A single JSON document of income and expenses as documented in Coding-exercise-instructions.md.

Example 3:

Produce income and expense report that excludes credit card payments.

python3.6 capitalone.py --email interview@levelmoney.com --password password2 --ignore-cc-payments

Output:

A single JSON document with two fields: income-and-expenses and cc-payments. The income-and-expenses field is formatted as documented in Coding-exercise-instructions.md. The cc-payments field lists all credit card transactions that were ignored.

Example 4:

Produce income and expense report that excludes credit card payments and donut expenses.

python3.6 capitalone.py --email interview@levelmoney.com --password password2 --ignore-cc-payments --ignore-donuts

Output:

A single JSON document with two fields: income-and-expenses and cc-payments. The income-and-expenses field is formatted as documented in Coding-exercise-instructions.md. The cc-payments field lists all credit card transactions that were ignored.

Requirements

The capitalone package requires Python 3.6 and these packages:

1. pytest
2. requests

Setup instructions are provided for Debian (not verified).

Setup instructions

The setup instructions depend on your platform and its package manager.

On Debian 3.16

TODO: Test these instructions. (We leave this for another day.)

sudo apt update
sudo apt install python3.6
sudo python3.6 -m ensurepip
sudo python3.6 -m pip install pytest requests

On Fedora 25

sudo dnf install python3.6
sudo python3.6 -m ensurepip
sudo python3.6 -m pip install pytest requests

On macOS Sierra

If you are using homebrew as your package manager, execute these commands:

sudo brew update
sudo brew install python36
sudo python3.6 -m ensurepip
sudo python3.6 -m pip install pytest requests

Please note that David Noble is a Mac Ports user. Please accept the homebrew instructions as an approximation.

If you are using Mac Ports as your package manager, execute these commands:

sudo port selfupdate
sudo port install python36
sudo python3.6 -m ensurepip
sudo python3.6 -m pip install pytest requests

On Windows 10

Download and install Python 3.6 from [https://www.python.org/downloads/windows/], ensure that Python 3.6 is on your path and then execute this command from an elevated command line window:

python3.6 -m pip install pytest requests