Convert unit tests to Pytest (#276)

This PR modernizes the testing framework replacing the unittest
framework with pytest. pytest provides clearer assertions, powerful
fixtures, and an extensive plugin ecosystem, which will make tests
easier to write, maintain, and extend going forward.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: NoodlesNZ

.github/workflows/main.yml

@@ -25,21 +25,15 @@ jobs:
 
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
-    # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
-    - uses: actions/checkout@v3
-    # install newest pip
-    - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v4
-      with:
-        python-version: ${{ matrix.python-version }}
-    - name: Install pip
-      run: python -m pip install --upgrade pip setuptools wheel
-    # install requirements
-    - name: Install requirements
-      run: |
-        python -m pip install --upgrade pip
-        pip install -r requirements.txt
-    # Runs a set of commands using the runners shell
-    - name: Run pytm tests
-      run: |
-        python3 -m unittest
+      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
+      - uses: actions/checkout@v4
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v6
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install Poetry
+        run: pip install poetry
+      - name: Install dependencies
+        run: poetry install --with dev
+      - name: Run tests
+        run: poetry run pytest