mcp-arduino/TESTING_FIXES_SUMMARY.md

# FastMCP Testing Fixes Summary

## Issues Found and Fixed

### 1. Arduino Sketch Tests (`test_arduino_sketch.py`)
**Issue**: The `create_sketch` method calls `_open_file()` which opens sketch files in text editor during test runs.

**Fixed**:
- Added `with patch.object(sketch_component, '_open_file'):` to `test_create_sketch_already_exists`
- Pattern: Mock `_open_file` method to prevent file opening during tests

**Status**: ✅ FIXED - All Arduino sketch tests now pass

### 2. Integration Tests (`test_integration.py`)
**Issues**:
- Incorrect FastMCP resource access pattern: Used `.content` instead of `.read()`
- Incorrect FastMCP tool invocation pattern: Used `.invoke()` instead of `.run(arguments_dict)`
- Attempted to access `mcp_server.app.sketch_component` which doesn't exist
- Tools require active FastMCP context to run, causing "No active context found" errors

**Partially Fixed**:
- ✅ Resource access: Changed from `resource.content` to `await resource.read()`
- ✅ Tool invocation method: Changed from `tool.invoke()` to `tool.run({})`
- ❌ Context issues: Tools still need proper FastMCP context management
- ❌ Component access: Tests try to access non-existent `mcp_server.app` attribute

**Status**: 🟡 PARTIALLY FIXED - 10/18 tests pass, 8 still fail due to context issues

## Proper FastMCP Testing Patterns

### Resource Access Pattern
```python
# ❌ Incorrect
resource = await mcp_server.get_resource("uri")
content = resource.content

# ✅ Correct
resource = await mcp_server.get_resource("uri")
content = await resource.read()
```

### Tool Invocation Pattern
```python
# ❌ Incorrect
tool = await mcp_server.get_tool("tool_name")
result = await tool.invoke(param1="value1")

# ✅ Correct
tool = await mcp_server.get_tool("tool_name")
result = await tool.run({"param1": "value1"})
```

### Component Method Mocking
```python
# ❌ Incorrect (for integration tests)
with patch.object(mcp_server.app.sketch_component, '_open_file'):

# ✅ Correct (for component tests)
with patch.object(sketch_component, '_open_file'):
```

## Recommended Next Steps

### Option 1: Use FastMCP Testing Utilities
Rewrite integration tests to use `run_server_in_process` from `fastmcp.utilities.tests`:

```python
from fastmcp.utilities.tests import run_server_in_process

def test_server_integration():
    with run_server_in_process(create_server, config) as server_url:
        # Make HTTP/MCP requests to server_url
        # This provides proper context management
```

### Option 2: Simplify Integration Tests
Focus integration tests on:
- Server creation and component registration
- Tool/resource metadata validation
- Resource content validation (without execution)
- Error handling for invalid configurations

Remove complex workflow tests that require tool execution with context.

### Option 3: Use Component-Level Testing
Move detailed functionality tests to component-level tests where proper mocking can be applied:
- `test_arduino_sketch.py` - ✅ Already working
- `test_arduino_library.py`
- `test_arduino_board.py`
- etc.

## Files Modified

### `/home/rpm/claude/mcp-arduino-server/tests/test_arduino_sketch.py`
- Added `_open_file` mocking to `test_create_sketch_already_exists`
- All tests now pass ✅

### `/home/rpm/claude/mcp-arduino-server/tests/test_integration.py`
- Fixed resource access patterns (10 tests now pass)
- Fixed tool invocation method signatures
- Updated error condition assertions
- 8 tests still failing due to context management issues

## Security & Best Practices Applied

1. **File Opening Prevention**: All `_open_file` calls are mocked to prevent opening text editors during tests
2. **Subprocess Mocking**: Arduino CLI calls are properly mocked with `patch('subprocess.run')`
3. **Error Handling**: Tests properly handle error conditions (missing arduino-cli, etc.)
4. **Isolation**: Tests use temporary directories and proper cleanup

## FastMCP Architecture Compliance

The fixes follow proper FastMCP patterns:
- Resources use `.read()` method for content access
- Tools use `.run(arguments_dict)` method for execution
- Components are tested in isolation with proper mocking
- Integration tests focus on metadata and registration, not execution