fix: resolve Python package installation error in Code Quality workflow

 **Immediate Fix:**
- Fix 'pip install -e python/' error: package configuration is in repository root, not python/ subdirectory
- Update Code Quality workflow to use PYTHONPATH approach for Python fallback testing
- Replace incorrect package installation with proper module path setup
- Add validation steps to ensure Python module can be imported before testing

 **Package Structure Clarification:**
- pyproject.toml and package configuration are in repository root (correct)
- python/demopy/ contains Python fallback implementation (correct)
- Workflow now uses PYTHONPATH=python approach for testing fallback code
- Removed attempt to install non-existent python/pyproject.toml

 **Comprehensive Testing Infrastructure:**
- Create scripts/test_python_structure.py for package structure validation
- Create scripts/test_ci_python.py for complete CI simulation
- Add validation of Python fallback import and functionality
- Test all package functions (hello, add, multiply, sum_list, reverse_string, power)

 **Development Experience:**
- Add validate-python and test-python-fallback commands to Makefile
- Integrate Python structure validation into development setup
- Provide clear feedback on package import status and functionality
- Enable local testing of exact CI workflow steps

 **Code Quality Fixes:**
- Fix flake8 linting issues (import order, line length)
- Add noqa comments for necessary import order exceptions
- Format code with black and isort for consistency
- Ensure all Python quality checks pass locally

 **Expected Resolution:**
- Code Quality workflow should complete Python steps without installation errors
- Python fallback code should be properly testable via PYTHONPATH approach
- All Python quality checks (black, isort, flake8, mypy, pytest) should pass
- Package functionality should be validated in CI environment

**Root Cause:** Workflow tried to install package from python/ subdirectory, but package configuration (pyproject.toml) is in repository root. The python/ directory only contains the fallback implementation code.

**Solution:** Use PYTHONPATH approach to make Python fallback code importable for testing, rather than attempting package installation from incorrect location.

Author: jj-devhub

.github/workflows/code-quality.yml

@@ -84,8 +84,17 @@ jobs:
     - name: Install Python dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install black isort flake8 mypy pytest
-        pip install -e python/
+        pip install black isort flake8 mypy pytest maturin
+
+    - name: Setup Python package for testing
+      run: |
+        # For Python quality checks, we need to make the Python code importable
+        # Add the python directory to PYTHONPATH for testing the fallback code
+        echo "PYTHONPATH=${PYTHONPATH}:$(pwd)/python" >> $GITHUB_ENV
+
+        # Validate that the package can be imported
+        python -c "import sys; sys.path.insert(0, 'python'); import demopy; print('✅ demopy module imported successfully')"
+        python -c "import sys; sys.path.insert(0, 'python'); import demopy; print('Package version:', demopy.__version__)"
     
     - name: Check Python formatting (Black)
       run: black --check --diff python/ tests/
@@ -102,7 +111,14 @@ jobs:
 
     - name: Run Python tests
       run: |
+        # Ensure Python can find the demopy module
         export PYTHONPATH="${PYTHONPATH}:$(pwd)/python"
+        echo "PYTHONPATH: $PYTHONPATH"
+
+        # Test that the module can be imported
+        python -c "import sys; sys.path.insert(0, 'python'); import demopy; print('✅ demopy module imported successfully')"
+
+        # Run the actual tests
         pytest tests/ -v
 
   yaml-quality:

Makefile

@@ -187,3 +187,13 @@ tools-list:
 tools-clean:
 	@echo "🧹 Cleaning Rust tool cache..."
 	python scripts/install_rust_tools.py --mode clean
+
+# Validate Python package structure
+validate-python:
+	@echo "🔍 Validating Python package structure..."
+	python scripts/test_python_structure.py
+
+# Test Python fallback only
+test-python-fallback:
+	@echo "🐍 Testing Python fallback implementation..."
+	PYTHONPATH=python python -c "import demopy; print('Version:', demopy.__version__); print('Hello:', demopy.hello())"

python/demopy/__init__.py

@@ -8,20 +8,15 @@
 
 try:
     # Import the Rust extension
-    from demopy_gb_jj._rust import (
-        hello as _rust_hello,
-        add,
-        multiply,
-        sum_list,
-        reverse_string,
-        power,
-    )
-    
+    from demopy_gb_jj._rust import add
+    from demopy_gb_jj._rust import hello as _rust_hello
+    from demopy_gb_jj._rust import multiply, power, reverse_string, sum_list
+
     # Use the Rust implementation for hello
     def hello():
         """Return a greeting message from the Rust extension."""
         return _rust_hello()
-    
+
     # Export all functions
     __all__ = [
         "hello",
@@ -30,34 +25,34 @@ def hello():
         "sum_list",
         "reverse_string",
         "power",
-        "__version__"
+        "__version__",
     ]
-    
+
 except ImportError:
     # Fallback to pure Python implementation if Rust extension is not available
     def hello():
         """Return a greeting message (pure Python fallback)."""
         return "Hello from demopy_gb_jj (Python fallback)!"
-    
+
     def add(a, b):
         """Add two numbers (pure Python fallback)."""
         return a + b
-    
+
     def multiply(a, b):
         """Multiply two numbers (pure Python fallback)."""
         return a * b
-    
+
     def sum_list(numbers):
         """Sum a list of numbers (pure Python fallback)."""
         return sum(numbers)
-    
+
     def reverse_string(s):
         """Reverse a string (pure Python fallback)."""
         return s[::-1]
 
     def power(base, exponent):
         """Calculate the power of a number (base^exponent) (pure Python fallback)."""
-        return base ** exponent
+        return base**exponent
 
     __all__ = [
         "hello",
@@ -66,5 +61,5 @@ def power(base, exponent):
         "sum_list",
         "reverse_string",
         "power",
-        "__version__"
+        "__version__",
     ]

scripts/setup_dev_environment.py

@@ -157,14 +157,20 @@ def run_initial_checks():
     print("\n" + "="*50)
     print("🔍 RUNNING INITIAL QUALITY CHECKS")
     print("="*50)
-    
+
+    # First validate Python package structure
+    success = run_command("python scripts/test_python_structure.py", "Validate Python package structure", check=False)
+    if not success:
+        print("⚠️  Python package structure validation failed, but continuing...")
+
     checks = [
         ("cargo fmt --all -- --check", "Check Rust formatting"),
         ("cargo clippy --all-targets --all-features -- -D warnings", "Run Rust linting"),
         ("cargo test", "Run Rust tests"),
         ("black --check python/ tests/", "Check Python formatting"),
         ("isort --check-only python/ tests/", "Check Python import sorting"),
         ("flake8 python/ tests/", "Run Python linting"),
+        ("PYTHONPATH=python python -c 'import demopy; print(\"Python fallback works:\", demopy.hello())'", "Test Python fallback import"),
     ]
 
     results = []