TDD Exercise

This repository is part of the problem set and class activity for Intro to Tests in Unit 1.

Learning Goals

• Practice identifying test cases
• Practice writing tests with pytest
• Practice the Test Driven Development (TDD) programming workflow

About BlackJack

In this exercise we will write a method and set of tests in TDD fashion which calculates a hand's BlackJack score.

In the card game BlackJack each card has a value.

• Number cards (2-10) carry the card's numeric value.
• Face cards on the other hand ("Jack", "Queen", "King") have a value of 10.
• Aces (1) can have a value of either 1 or 11, whichever will get the hand closest to 21 without going over.

For example if I had a 3, a King, and an Ace, my BlackJack score is 14 (3 + 10 + 1). If I have an Ace, and a Jack then my score is 21 (11 + 10).

A hand, an array of Card values, must be between 2 and 5 items inclusive.

When a hand's score is greater than 21, the hand is a bust and the player automatically loses.

Problem Set

Part 1: Identifying Edge & Nominal Cases

Identify some of the following tests cases and record your responses in Learn.

• At least two nominal cases
• At least three edge cases

Note: You should not implement the tests or the functionality in Part 1.

Classroom Activity

Part 2: Identifying Edge & Nominal Cases

In class, you will:

1. Review the test cases you identified in Part 1
2. Determine how you would test these cases

One-Time Problem Set Setup for Part 2

Follow these directions once when you start working on this Part 2 during roundtables:

1. Navigate to your projects folder named projects

$ cd ~/Developer/projects

1. In Github, fork the project then click on the green "Code" button in Github and then copy the URL. This will allow you to download a copy of this project into your projects folder. This command makes a new folder called tdd-exercise, and then puts the project into this new folder.

After copying the URL, run the following command in your terminal:

$ git clone <paste your copied URL here>

Use ls to confirm there's a new project folder

1. Move your location into this project folder

$ cd tdd-exercise

2. Create a virtual environment named venv for this project:

$ python3 -m venv venv

3. Activate this environment:

$ source venv/bin/activate

Verify that you're in a python3 virtual environment by running:

• $ python --version should output a Python 3 version
• $ pip --version should output that it is working with Python 3

4. Install dependencies once at the beginning of this project while your virtual environment is activated. Note that (venv) is not part of the command below that you need to run.

$ (venv) pip install -r requirements.txt

Part 3: Calculating a Score

We will write a method called: blackjack_score which take a list of card values and returns the blackjack score. The card values can be any of the following, number values 2-10, "King", "Queen", "Jack", and "Ace". For example blackjack_score(["Ace", 5, 3]) will return 19. If the list contains an invalid card value or the hand contains more than 5 cards, return "Invalid". If the total exceeds 21, return "Bust".

Note: These last two cases may be better handled by raising an exception (as opposed to returning "Invalid" and "Bust").We can consider that when we learn more about raising exceptions.

In this exercise we will complete the given tests in test_blackjack_score.py and update the blackjack_score function in main.py to make it pass.

• Step 1: Complete the given test and comment out @pytest.mark.skip
• Step 2: Update blackjack_score to pass the test. Execute the tests by running the command pytest in the terminal.
• Step 3: Move to the next test

We will likely not have time to write every test and implement every piece of code to implement a complete blackjack_score function. Keep in mind that the learning goals for this activity are to practice identifying test cases, practice writing tests with pytest, and practice working in a TDD fashion.