Capital Gains

Calculate the tax the user needs to pay based on the profit or losses of a stock market investment

Technical and architectural decisions

• Why Python: Because is the programming lenguage that I used daily and I have more experience, is easy to mantain and for the purpose of the app it can be undestood very easly.
• I used the Singleton Design Pattern: The clases ReadJson and CapitalGains classes to ensure that only one instance of each is created during execution
  • ReadJson is responsible for parsing the input string into JSON object, and having a single instance avoids redundant parsing logic across modules.
  • CapitalGains centralizes the tax calculation logic, ensuring consistency.
• I didn't use a database: The app does not require a database connection, as it doesn’t need to persist any information.
• Architecture: This is a script-style app designed to be used from the console. The user can run the script, provide a JSON string, and receive tax calculations as output.

Requirements

• Python 3.13.0 (local development)
• All the libraries used by the app are in "requirements.txt"

Libries used in the project

Pytest: library used for creating tests for the app.

How to run it locally

• Install the dependecies:

 pip install -r requirements.txt  

• Run the following command:

python main.py -j '[{"operation":"buy","unit-cost":10.0,"quantity":100},{"operation":"sell","unit-cost":15.0,"quantity":50},{"operation":"sell","unit-cost":15.0,"quantity":50}]'

How to run it using Docker

1. Create the build

docker build -t capital-gains .

2. Run the container, this will create a new instance of the container

docker run -it capital-gains  

3. It will enter to the console, you will see:

root@cb8dbed4c114:/app# 

4. To run the app, use the command:

python main.py -j '[{"operation":"buy","unit-cost":10.0,"quantity":100},{"operation":"sell","unit-cost":15.0,"quantity":50},{"operation":"sell","unit-cost":15.0,"quantity":50}]'

How to run the unit and integration tests

• These commands can be used locally or inside the docker container
• Run the following command for running unit and integration tests:

pytest tests/

• Run the following command for integration tests:

pytest tests/integration/

• Run the following command for running unit tests:

pytest tests/unit/

Examples

• Console command:
• Tests:
• Tests Coverage: