Capital Gains Calculator

This project is a Go application that calculates capital gains taxes based on a series of buy and sell transactions.

Technical and Architectural Decisions

• The project was developed using Go mainly due to its simplicity and binary compilation, which makes it easy to distribute and run the application on different platforms.
• Docker was used to facilitate the distribution and execution of the application, as well as to ensure that it runs in the same environment regardless of the host machine.
• There's also a Makefile to facilitate the building, testing, and running of the application, as well as the creation and running of Docker containers.

Project Structure

The project was structured to clearly separate responsibilities:

• bin: Where the executable binary is stored when the application is compiled.
• cmd/cli/main.go: Contains the application's entrypoint.
• cmd/cli/internal/testdata: Contains test data files.
• internal/domain: Contains the domain entities and the logic for calculating capital gains.

Build and Execution

Build

To build the application, run:

Note: Go is required to build the application locally.

make build

A binary will be generated in the bin directory.

Run Locally

To run the application, use:

./bin/capital-gains < input.json

There are some test data files in the cmd/cli/internal/testdata directory that can be used as input, like:

./bin/capital-gains < ./cmd/cli/internal/testdata/case_1_input.golden

It's also possible to run the application with the following command:

./bin/capital-gains

And then type the transactions manually.

Tests

To run the tests, run:

make test

To run the tests with coverage, use:

make test-coverage

Docker

To build the Docker image, run:

make docker-build

To run the application inside a Docker container, use:

make docker-run

You can interact the same way as running the application locally.

Help

To display the commands available in the Makefile, run:

make help

Additional Notes

• Custom JSON Marshaller: I have implemented a custom JSON marshaller for the Tax structure to ensure that values ​​are rounded to two decimal places. This is a silly workaround, but it was the simplest way to achieve this.
• Parallel Tests: Tests run using t.Parallel() to ensure that they are executed concurrently, improving test efficiency, and to guarantee that they are isolated from each other.