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Stock portfolio report program

Project description

Stock Portfolio

This assignment will test the following skills:

  • Reading and writing to the file system
  • Making HTTP requests
  • Testing read & write operations to the disk
  • Testing HTTP requests using a mock library
  • Packaging the script using


Write a program which will generate up-to-date performance reports for a given stock portfolio. The program will accept two arguments: an input CSV file which contains the holdings information, and, a path to output the CSV report.

We will use the IEX Trading API, as the market data source – it is a public (free) API.


The program will read a CSV file containing our portfolio data. Based on this data, a new CSV report will be generated using live market value to indicate our current holding performance using the IEX API.

The program will be installable using pip, and requires a file. When installed, a binary will be added to the Python path which can be invoked from anywhere on the filesystem.

An example interaction with the script looks like this:

$ portfolio_report --source portfolio.csv --target report1.csv

Input file

The input CSV will have 3 columns (example provided).

  • symbol: the ticker symbol (e.g. AAPL is Apple)
  • units: the quantity of shares held
  • cost: the original / average purchase price of the holding


symbol units cost
AAPL 1000 123.56
AMZN 20 2001.1

Using the list of symbols from the input CSV, get quotes from IEX to fetch the latest price. This can be done in a batch request – meaning, multiple quotes can be requested in a single HTTP request. See:


Example request & response

Example request: GET the latest quotes for Apple, Facebook & Snapchat:,AMZN,SNAP

    "symbol": "AAPL",
        "price": 204.29,
        "size": 100,
        "time": 1563307196175
}, {
    "symbol": "AMZN",
        "price": 2008.395,
        "size": 1,
        "time": 1563307196058
}, {
    "symbol": "SNAP",
        "price": 15,
        "size": 100,
        "time": 1563307196047

Once the latest price is obtained, a series of calculations are made to establish the current performance of the portfolio: what the current market value is, the gain and loss for each holding and a percentage of change.

If a symbol listed in the input CSV is not found on the exchange, the IEX API ignores it. Your script should account for this situation by warning the user that the symbol was not found, but continue to process the rest of the valid symbols.

Output file

The expected CSV report will have the following columns

  • symbol: The stock ticker symbol (i.e. AAPL)
  • units: The amount of shares held
  • cost: The original cost per share
  • latest_price: The latest market price per share
  • book_value: The value of the shares at time of purchase
  • market_value: The value of the shares based on the latest market value
  • gain_loss: The dollar amount either gained or lost
  • change: A percentage (decimal) of the gain/loss
Sample output CSV
symbol units cost latest_price book_value market_value gain_loss change
AAPL 1000 123.56 156.23 12356 15623 3267 0.264
AMZN 20 2001.1 1478.19 40022 29563 -10459 -0.261

Getting started

Take a modular approach to completing this assignment and build each functional component in isolation, accompanied by appropriate tests.

Here is a breakdown of isolated functional units:

  • Given a filename, read a CSV and convert it to a Python data structure
  • Build a method which returns the latest market price for holdings
  • Build methods which calculate the book value, market value
  • Build a method to convert the holding into CSV
  • Build a method that writes to the output filename.


Testing against third-party services can be challenging as they are out of our control. As developers, we must build our application with the expectation of specific behaviours from these services. Mocks (faking) are a handy way to isolate the dependency and replace it with a constant to which we can build tests. For this, we will use the requests-mock library to stub out HTTP requests.

Install using pip install requests-mock.

As for writing files, use the tmp_path fixture that ships with pytest to write to temporary locations on the disk.

Make sure to update requirements.txt and include any libraries required to build this project (e.g. requests, requests-mock) so they are available to Travis CI.


As described above, provide a configuration to package your application. Ensure that dependencies required to run your script are included (e.g. requests)

Evaluation rubric

Metric 4 3 2 1 0
Meets requirements All requirements are met Almost all requirements are met Most requirements met, some bugs Incorrect results, several bugs Program does not work
Testing Unit tests are present and cover all functionality Most of the script is covered by testing Partial test coverage, some false assertions present Minimal testing, false assertions present, missing main functional coverage. No meaningful tests exist
Packaging & delivery The project is properly packaged, documented and can be installed using pip. The project is packaged, but is missing certain metadata The project is installable, but with some issues. Documentation is incomplete. Documentation is partial, the package does not install No packaging present, little or no documentation
Reusability The code could be reused as a whole and each routine could be reused Most of the code could be reused in other programs Some parts of the code could be reused in other programs A few parts of the code could be reused in other programs The code is not organized for reusability
Readability The code is well organized and very easy to understand The code is pretty well organized and fairly easy to read The code has some organization, is a challenge to read The code is readable only by someone who knows what it is supposed to do The code is poorly organized and very difficult to read

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