# Testing Guide for GIS MCP Server
## Issue: FunctionTool is not callable
The tests are currently failing because FastMCP wraps functions with `@tool()` decorator, which creates `FunctionTool` objects that are not directly callable.
## Solution: Use FastMCP Client Pattern
According to the [FastMCP testing documentation](https://mcpcat.io/guides/writing-unit-tests-mcp-servers/), tests should use the `Client` class to call tools through the MCP protocol.
## Pattern to Follow
### Before (doesn't work):
```python
from gis_mcp import shapely_functions
def test_buffer():
result = shapely_functions.buffer(point.wkt, distance=10.0) # ❌ TypeError
```
### After (correct pattern):
```python
import pytest
import json
from fastmcp import Client
from gis_mcp.mcp import gis_mcp
@pytest.mark.asyncio
async def test_buffer():
point = Point(0, 0)
async with Client(gis_mcp) as client:
result = await client.call_tool("buffer", {
"geometry": point.wkt,
"distance": 10.0
})
result_data = json.loads(result[0].text)
assert result_data["status"] == "success"
```
## Helper Function
A helper function is available in `test_helpers.py`:
```python
from tests.test_helpers import call_tool
@pytest.mark.asyncio
async def test_buffer():
point = Point(0, 0)
result = await call_tool("buffer", geometry=point.wkt, distance=10.0)
assert result["status"] == "success"
```
## Converting Existing Tests
1. Add `@pytest.mark.asyncio` decorator to test functions
2. Make test functions `async`
3. Replace direct function calls with `Client` pattern or use `call_tool` helper
4. Parse JSON result: `json.loads(result[0].text)`
## Rasterio CRS Fix
For rasterio tests, use `rasterio.crs.CRS.from_epsg(4326)` instead of `'EPSG:4326'`:
```python
import rasterio.crs
with rasterio.open(
test_file,
'w',
crs=rasterio.crs.CRS.from_epsg(4326), # ✅ Correct
# ... other params
) as dst:
dst.write(data)
```
## Next Steps
All test files need to be updated to use the async Client pattern. This is a systematic refactoring that should be done file by file.
