WOLT 2024 internship pre-assignment

This is my solution for WOLT's 2024 internship pre-assignment

Table of contents

• WOLT 2024 internship pre-assignment
  • Table of contents
  • Working with the project
    • Run project using docker
    • Run project directly with Python 3
    • Run tests
    • Get coverage report
  • Project structure
    • Class relationships

Working with the project

Run project using docker

To run the project locally, it is recommended to use docker. So for that you will need docker installed on your machine. If you don't have docker installed, you can follow the instructions here.

To run project using docker, open the terminal in the project base directory, this means the the directory where the Dockerfile is located. Then run the following command:

docker compose up --build

To see the docs of the api endpoints, open your browser and go to http://localhost:80/docs.

To stop the project, press Ctrl + C in the terminal and then run the following command:

docker compose down

Run project directly with Python 3

To run this project without docker, you will have to have Python 3 installed on your machine. I recommend using Python version 3.12.0, this is the version I used during development. You can download python from here. When you have python installed, you will need to install the dependencies. To do so run the following command in the terminal:

pip install -r requirements.txt

Note: You might need to use pip3 instead of pip depending on your python installation. And also your current directory should be the project base directory, this means the the directory where the requirements.txt is located.

After installing the dependencies, you can run the project by running the following command in the terminal:

uvicorn app.main:app --host 127.0.0.1 --port 8000

Then open your browser and go to http://localhost:8000/docs to see the docs of the api endpoints.

Note: Of course, you will have to be in the project's base directory(ie. where Dockerfile and README.md file is located) to for this command to work.🙂

Run tests

To run the tests, open the terminal in the project base directory, this means the the directory where the pytest.ini is located. Then run the following command:

pytest -v

Note: You should have the project dependencies installed before running the tests.

Get coverage report

To get the coverage report, open the terminal in the project base directory, this means the the directory where the pytest.ini is located. Then run the coverage.sh or coverage.ps1 depending on your operating system.

Project structure

All the files related to the project are located in the app directory. The app directory contains the following files and directories:

.
│   main.py
│   __init__.py
│
├───delivery_fee
│       fee_calculation_steps.py
│       fee_calculator.py
│       fee_transformers.py
│       models.py
│       router.py
│       settings.py
│       utility_meta_classes.py
│       __init__.py
│
└───tests
    │   test_main.py
    │   __init__.py
    │
    └───delivery_fee
        │   test_fee_calculator_initialization.py
        │   __init__.py
        │
        ├───calculation_steps
        │       test_cart_value_fee.py
        │       test_delivery_distance_fee.py
        │       test_number_of_items_fee.py
        │       __init__.py
        │
        ├───calculation_transformers
        │       test_limit_fee_transformer.py
        │       test_reduce_fee_transformer.py
        │       test_rush_hour_fee_transformer.py
        │       __init__.py
        │
        └───model
                test_delivery_fee.py
                test_order_info.py

• ./app/tests/ has all the test cases organized logically under corresponding subfolders. The subfolders is created for each module in the ./app/delivery_fee/ directory on when the number of test cases are too much to store in one file.
• main.py is the entry point of the application.
• ./app/delivery_fee/ has all the modules related to the delivery fee calculation.
• ./app/delivery_fee/router.py has the router for the delivery fee calculation api.
• ./app/delivery_fee/models.py has the pydantic models used in the api these are used for data parsing.
• ./app/delivery_fee/settings.py has the settings for the delivery fee calculation api.
• ./app/delivery_fee/utility_meta_classes.py has the utility meta classes these are used to create the singleton classes.
• ./app/delivery_fee/fee_calculator.py has the fee calculator class which is used to calculate the delivery fee.
• ./app/delivery_fee/fee_calculation_steps.py has the fee calculation steps which are used to calculate the delivery fee. These does not modify the fee, they calculate fee depending on the order info.
• ./app/delivery_fee/fee_transformers.py has the fee transformers which are used to modify the fee. These does not calculate the fee, they modify the fee depending on the order info.
• ./app/delivery_fee/fee_calculator.py has the fee calculator class which is used to first follow the delivery calculation steps and then applies the transformers to apply any rules on the calculated fee.

Class relationships

• DeliveryFeeTransformer and DeliveryFeeCalculationStep are interfaces. These are implemented by the other classes in the fee_transformers.py and fee_calculation_steps.py files respectively. Each of these classes has their own ConfigOptions sub class which holds the options when calculating or transforming the fee.
• DeliveryFeeCalculator is the main class which is used to calculate the delivery fee. It uses the DeliveryFeeCalculationStep and DeliveryFeeTransformer classes to calculate and transform the fee.