Update cursor rules to mandate pytest for all testing

- Add explicit pytest requirement to testing-patterns.mdc
- Update user-preferences.mdc to include pytest preference
- Modify development-workflow.mdc to reference pytest usage
- Specify that all tests must use pytest framework
- Document pytest features to use (classes, fixtures, assertions)
- Add comprehensive examples of proper pytest structure
- Include DO NOT USE section for prohibited testing approaches
- Ensure CLI integration expects pytest-compatible test files
- Make it clear that manual testing and other frameworks are not allowed

.cursor/rules/development-workflow.mdc

@@ -10,7 +10,7 @@ The main development tool is [bin/tito.py](mdc:bin/tito.py). Common commands:
 # Sync module: Python source → notebook → package export
 python bin/tito.py sync --module {module_name}
 
-# Test specific module
+# Test specific module (uses pytest internally)
 python bin/tito.py test --module {module_name}
 
 # Get project info and status
@@ -41,7 +41,8 @@ python bin/tito.py test --module tensor
    - Updates package structure
 
 3. **Test**: `python bin/tito.py test --module {module}`
-   - Runs module-specific tests from `modules/{module}/tests/`
+   - Runs module-specific pytest tests from `modules/{module}/tests/`
+   - Uses pytest framework for all test execution
    - Validates exported package code
    - Ensures everything works end-to-end
 
@@ -49,6 +50,13 @@ python bin/tito.py test --module tensor
    - User prefers committing when reaching good milestones
    - Clean up experimental files before committing
 
+## Testing Requirements
+
+- **All tests must use pytest** - No manual testing or other frameworks
+- Test files must be named `test_{module}.py` and located in `modules/{module}/tests/`
+- Tests should use pytest classes, fixtures, and assertions
+- CLI tool uses pytest internally: `subprocess.run([sys.executable, "-m", "pytest", test_file, "-v"])`
+
 ## File Relationships
 
 ```
@@ -56,7 +64,7 @@ modules/{module}/{module}_dev.py  →  modules/{module}/{module}_dev.ipynb
                                  ↓
                             tinytorch/core/{component}.py
                                  ↑
-                    modules/{module}/tests/test_{module}.py
+                    modules/{module}/tests/test_{module}.py (pytest)
 ```
 
 ## Module Structure
@@ -66,10 +74,7 @@ Each module should be self-contained with:
 - `{module}_dev.ipynb` - Generated notebook (auto-created)
 - `README.md` - Module documentation
 - `tests/` - Test directory
-  - `test_{module}.py` - Module tests
+  - `test_{module}.py` - Module tests (pytest format)
 
-Students run and pass all tests locally within the module before using nbdev to export code to the tinytorch package and build/test the overall package.
- 
-
-Students run and pass all tests locally within the module before using nbdev to export code to the tinytorch package and build/test the overall package.
+Students run and pass all pytest tests locally within the module before using nbdev to export code to the tinytorch package and build/test the overall package.
  

.cursor/rules/testing-patterns.mdc

@@ -1,6 +1,10 @@
 
 # Testing Patterns for TinyTorch
 
+## Testing Framework Requirement
+
+**ALWAYS USE PYTEST** - TinyTorch uses pytest as the standard testing framework for all tests. Never use manual testing, unittest, or custom test runners. All test files must be compatible with pytest.
+
 ## Test File Structure
 
 ### Module Tests (`modules/{module}/tests/test_{module}.py`)
@@ -8,11 +12,13 @@
 - Validate both student TODOs and hidden solutions
 - Should work with both incomplete and complete implementations
 - Import from the parent module's development file
+- **Must use pytest** with proper test classes and assertions
 
 ### Package Tests (`tinytorch/tests/`)  
 - Test the exported package functionality
 - Integration tests across components
 - Production-level validation
+- **Must use pytest** with comprehensive test coverage
 
 ## Test Naming Convention
 
@@ -27,7 +33,9 @@ tinytorch/tests/test_tensor.py
 tinytorch/tests/test_autograd.py
 ```
 
-## Test Structure Pattern
+## Test Structure Pattern (REQUIRED)
+
+**All tests must follow this pytest pattern:**
 
 ```python
 import pytest
@@ -65,20 +73,32 @@ class TestComponentName:
         pass
 ```
 
+## pytest Features to Use
+
+- **Test classes** for organizing related tests
+- **pytest fixtures** for setup/teardown (e.g., `capsys`, `monkeypatch`)
+- **Parametrized tests** for testing multiple inputs
+- **pytest.raises()** for exception testing
+- **assert statements** with descriptive messages
+- **Test discovery** - pytest automatically finds test files
+
 ## Running Tests
 
 ```bash
-# Test specific module
+# Test specific module (recommended)
 python bin/tito.py test --module tensor
 
 # Test all modules
 python bin/tito.py test --all
 
-# Run specific test file directly
+# Run specific test file directly with pytest
 python -m pytest modules/tensor/tests/test_tensor.py -v
 
 # Run from within module directory
 cd modules/tensor && python -m pytest tests/ -v
+
+# Run with coverage
+python -m pytest modules/tensor/tests/ --cov=tensor_dev -v
 ```
 
 ## Test Categories
@@ -90,10 +110,81 @@ cd modules/tensor && python -m pytest tests/ -v
 
 ## Key Testing Principles
 
+- **Always use pytest** - No exceptions, no manual testing
 - Tests should pass with both TODO stubs and complete implementations
 - Educational tests should guide student learning
 - Package tests ensure production readiness
 - All tests should be fast and isolated
 - Use descriptive test names that explain what's being tested
 - Import from module development files, not the package (for module tests)
+- Use pytest fixtures for common setup/teardown operations
+- Group related tests in test classes
+- Use parametrized tests for multiple similar test cases
+
+## Example Comprehensive Test Structure
+
+```python
+import pytest
+from pathlib import Path
+import sys
+
+# Add parent directory to path
+sys.path.insert(0, str(Path(__file__).parent.parent))
+
+from setup_dev import hello_tinytorch, SystemInfo, DeveloperProfile
+
+class TestBasicFunctions:
+    """Test basic module functions."""
+    
+    def test_hello_tinytorch_executes(self):
+        """Test function runs without error."""
+        hello_tinytorch()
+    
+    def test_hello_tinytorch_output(self, capsys):
+        """Test function produces expected output."""
+        hello_tinytorch()
+        captured = capsys.readouterr()
+        assert "TinyTorch" in captured.out
+
+class TestSystemInfo:
+    """Test SystemInfo class."""
+    
+    def test_creation(self):
+        """Test class instantiation."""
+        info = SystemInfo()
+        assert hasattr(info, 'python_version')
+    
+    def test_compatibility(self):
+        """Test compatibility checking."""
+        info = SystemInfo()
+        assert isinstance(info.is_compatible(), bool)
+
+class TestFileOperations:
+    """Test file-related operations."""
+    
+    def test_missing_file_handling(self, monkeypatch):
+        """Test graceful handling of missing files."""
+        # Use monkeypatch to mock file operations
+        pass
+```
+
+## DO NOT USE
+
+- Manual test runners (custom functions that execute tests)
+- unittest framework
+- Simple assert statements without pytest structure
+- Print-based testing
+- Custom test discovery mechanisms
+- Any testing approach that doesn't integrate with pytest
+
+## Integration with TinyTorch CLI
+
+The `tito.py` CLI tool expects pytest-compatible test files and uses pytest internally:
+
+```python
+# In bin/tito.py
+result = subprocess.run([sys.executable, "-m", "pytest", test_file, "-v"])
+```
+
+This ensures all tests run through pytest with consistent output and reporting.
  

.cursor/rules/user-preferences.mdc

@@ -1,7 +1,3 @@
----
-alwaysApply: true
-description: User preferences and conventions for the TinyTorch educational framework.
----
 
 # User Preferences and Conventions
 
@@ -11,6 +7,7 @@ description: User preferences and conventions for the TinyTorch educational fram
 - **Commit frequency**: Check code into repo at good milestone stages
 - **README focus**: Keep main project README focused on overarching goals, not module details
 - **Component terminology**: Call code components 'modules' instead of 'parts'
+- **Testing framework**: Always use pytest for all tests - no manual testing or other frameworks
 
 ## Educational Workflow
 
@@ -31,9 +28,15 @@ description: User preferences and conventions for the TinyTorch educational fram
 - **Educational directives**: Use `#| hide` for instructor solutions, visible sections for student work
 - **Package structure**: Code exports from `modules/` to `tinytorch/` package
 
-These preferences ensure consistency across the TinyTorch educational framework and smooth development workflow.
+## Testing Standards
 
-- **Educational directives**: Use `#| hide` for instructor solutions, visible sections for student work
+- **pytest only**: All tests must use pytest framework with proper test classes
+- **Comprehensive coverage**: Tests should cover functionality, edge cases, and integration
+- **Professional structure**: Use test classes, fixtures, and descriptive test names
+- **CLI integration**: Tests must be compatible with `python bin/tito.py test --module {name}`
+
+These preferences ensure consistency across the TinyTorch educational framework and smooth development workflow.
+ 
 - **Package structure**: Code exports from `modules/` to `tinytorch/` package
 
 These preferences ensure consistency across the TinyTorch educational framework and smooth development workflow.