This script fetches historical stock data for a given stock symbol and date range from Yahoo Finance. It uses the yfinance library to retrieve the data and pandas to handle it. The script provides a command-line interface (CLI) for easy usage.

• Python 3.x

• The following Python libraries are required:

  • yfinance
  • pandas

  You can install them using pip:

  pip install yfinance pandas

To run the script, use the following command structure from your terminal:

python stock_data.py <SYMBOL> <START_DATE> <END_DATE>

Where:

• <SYMBOL>: The stock symbol you want to fetch data for (e.g., AAPL, MSFT, GOOGL).
• <START_DATE>: The beginning of the date range for the historical data. Must be in YYYY-MM-DD format.
• <END_DATE>: The end of the date range for the historical data. Must be in YYYY-MM-DD format.

Fetching Apple Inc. (AAPL) data for January 2023:

python stock_data.py AAPL 2023-01-01 2023-01-31

Fetching Microsoft Corp. (MSFT) data for a specific period in June 2022:

python stock_data.py MSFT 2022-06-01 2022-06-10

If the data is fetched successfully, the script will print the historical stock data to the console in a tabular format. Here's a snippet of what it might look like:

Data for AAPL from 2023-01-01 to 2023-01-05:
                                 Open        High  ...  Dividends  Stock Splits
Date                                               ...
2023-01-03 00:00:00-05:00  128.613985  129.226052  ...        0.0           0.0
2023-01-04 00:00:00-05:00  125.267339  127.014709  ...        0.0           0.0
... (more data rows) ...

(Note: The actual columns and data may vary slightly based on the information provided by Yahoo Finance.)

The script includes error handling for various situations:

• Invalid Date Format: If the START_DATE or END_DATE is not in the YYYY-MM-DD format, the script will print an error message and exit:

  Error: Date format must be YYYY-MM-DD.
  

• Invalid Symbol / No Data: If the stock symbol is invalid, or if no data is found for the given symbol and date range, an appropriate message will be printed to the console:

  Error fetching data for symbol INVALID_SYMBOL: <Error details from yfinance>
  

  or

  No data found for symbol AAPL from 1950-01-01 to 1950-01-05.
  

The project includes a suite of unit tests to ensure the script's functionality. To run these tests, navigate to the project directory in your terminal and execute:

python -m unittest test_stock_data.py

This will run the tests defined in test_stock_data.py and report the results.