use httpx.AsyncClient for async http requests
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Thomas Grainger
GitHub
parent
0de33b1981
commit
612d792fd3
1 changed files with 65 additions and 43 deletions
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@ -42,7 +42,7 @@ Let's build your first MCP server in Python! We'll create a weather server that
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<Step title="Install additional dependencies">
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```bash
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uv add requests python-dotenv
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uv add httpx python-dotenv
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```
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</Step>
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@ -69,8 +69,8 @@ Let's build your first MCP server in Python! We'll create a weather server that
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from functools import lru_cache
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from typing import Any
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import requests
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import asyncio
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import httpx
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import anyio
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from dotenv import load_dotenv
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from mcp.server import Server
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from mcp.types import (
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@ -108,20 +108,20 @@ Let's build your first MCP server in Python! We'll create a weather server that
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Add this functionality:
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```python
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# Create reusable session
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http = requests.Session()
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http.params = {
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# Create reusable params
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http_params = {
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"appid": API_KEY,
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"units": "metric"
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}
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async def fetch_weather(city: str) -> dict[str, Any]:
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response = http.get(
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f"{API_BASE_URL}/weather",
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params={"q": city}
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)
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response.raise_for_status()
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data = response.json()
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async with httpx.AsyncClient() as client:
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response = await client.get(
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f"{API_BASE_URL}/weather",
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params={"q": city, **http_params}
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)
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response.raise_for_status()
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data = response.json()
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return {
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"temperature": data["main"]["temp"],
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@ -167,7 +167,7 @@ Let's build your first MCP server in Python! We'll create a weather server that
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try:
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weather_data = await fetch_weather(city)
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return json.dumps(weather_data, indent=2)
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except requests.RequestException as e:
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except httpx.HTTPError as e:
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raise RuntimeError(f"Weather API error: {str(e)}")
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```
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@ -220,15 +220,17 @@ Let's build your first MCP server in Python! We'll create a weather server that
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days = min(int(arguments.get("days", 3)), 5)
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try:
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response = http.get(
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f"{API_BASE_URL}/{FORECAST_ENDPOINT}",
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params={
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"q": city,
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"cnt": days * 8 # API returns 3-hour intervals
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}
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)
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response.raise_for_status()
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data = response.json()
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async with httpx.AsyncClient() as client:
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response = await client.get(
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f"{API_BASE_URL}/{FORECAST_ENDPOINT}",
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params={
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"q": city,
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"cnt": days * 8, # API returns 3-hour intervals
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**http_params,
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}
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)
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response.raise_for_status()
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data = response.json()
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forecasts = []
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for i in range(0, len(data["list"]), 8):
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@ -245,7 +247,7 @@ Let's build your first MCP server in Python! We'll create a weather server that
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text=json.dumps(forecasts, indent=2)
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)
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]
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except requests.RequestException as e:
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except requests.HTTPError as e:
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logger.error(f"Weather API error: {str(e)}")
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raise RuntimeError(f"Weather API error: {str(e)}")
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```
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@ -273,11 +275,11 @@ Let's build your first MCP server in Python! We'll create a weather server that
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```python
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from . import server
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import asyncio
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import anyio
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def main():
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"""Main entry point for the package."""
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asyncio.run(server.main())
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anyio.run(server.main)
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# Optionally expose other important items at package level
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__all__ = ['main', 'server']
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@ -443,9 +445,10 @@ Let's build your first MCP server in Python! We'll create a weather server that
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<Card title="Error Handling" icon="shield">
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```python
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try:
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response = self.http.get(...)
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response.raise_for_status()
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except requests.RequestException as e:
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async with httpx.AsyncClient() as client:
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response = await client.get(..., params={..., **http_params})
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response.raise_for_status()
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except requests.HTTPError as e:
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raise McpError(
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ErrorCode.INTERNAL_ERROR,
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f"API error: {str(e)}"
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@ -565,12 +568,13 @@ uvicorn.run(app, host="0.0.0.0", port=8000)
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last_cache_time is None or
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now - last_cache_time > cache_timeout):
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response = http.get(
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f"{API_BASE_URL}/{CURRENT_WEATHER_ENDPOINT}",
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params={"q": city}
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)
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response.raise_for_status()
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data = response.json()
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async with httpx.AsyncClient() as client:
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response = await client.get(
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f"{API_BASE_URL}/{CURRENT_WEATHER_ENDPOINT}",
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params={"q": city, **http_params}
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)
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response.raise_for_status()
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data = response.json()
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cached_weather = {
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"temperature": data["main"]["temp"],
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@ -674,6 +678,10 @@ uvicorn.run(app, host="0.0.0.0", port=8000)
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DEFAULT_CITY
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)
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@pytest.fixture
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def anyio_backend():
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return "asyncio"
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@pytest.fixture
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def mock_weather_response():
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return {
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@ -706,7 +714,7 @@ uvicorn.run(app, host="0.0.0.0", port=8000)
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]
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}
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@pytest.mark.asyncio
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@pytest.mark.anyio
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async def test_fetch_weather(mock_weather_response):
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with patch('requests.Session.get') as mock_get:
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mock_get.return_value.json.return_value = mock_weather_response
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@ -720,7 +728,7 @@ uvicorn.run(app, host="0.0.0.0", port=8000)
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assert weather["wind_speed"] == 3.6
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assert "timestamp" in weather
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@pytest.mark.asyncio
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@pytest.mark.anyio
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async def test_read_resource():
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with patch('weather_service.server.fetch_weather') as mock_fetch:
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mock_fetch.return_value = {
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@ -736,12 +744,26 @@ uvicorn.run(app, host="0.0.0.0", port=8000)
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assert "temperature" in result
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assert "clear sky" in result
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@pytest.mark.asyncio
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@pytest.mark.anyio
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async def test_call_tool(mock_forecast_response):
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with patch('weather_service.server.http.get') as mock_get:
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mock_get.return_value.json.return_value = mock_forecast_response
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mock_get.return_value.raise_for_status = Mock()
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class Response():
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def raise_for_status(self):
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pass
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def json(self):
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return nock_forecast_response
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class AsyncClient():
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def __aenter__(self):
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return self
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async def __aexit__(self, *exc_info):
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pass
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async def get(self, *args, **kwargs):
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return Response()
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with patch('httpx.AsyncClient', new=AsyncClient) as mock_client:
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result = await call_tool("get_forecast", {"city": "London", "days": 2})
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assert len(result) == 1
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@ -751,14 +773,14 @@ uvicorn.run(app, host="0.0.0.0", port=8000)
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assert forecast_data[0]["temperature"] == 18.5
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assert forecast_data[0]["conditions"] == "sunny"
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@pytest.mark.asyncio
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@pytest.mark.anyio
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async def test_list_resources():
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resources = await list_resources()
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assert len(resources) == 1
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assert resources[0].name == f"Current weather in {DEFAULT_CITY}"
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assert resources[0].mimeType == "application/json"
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@pytest.mark.asyncio
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@pytest.mark.anyio
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async def test_list_tools():
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tools = await list_tools()
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assert len(tools) == 1
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@ -768,7 +790,7 @@ uvicorn.run(app, host="0.0.0.0", port=8000)
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</Step>
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<Step title="Run tests">
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```bash
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uv add --dev pytest pytest-asyncio
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uv add --dev pytest
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uv run pytest
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```
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</Step>
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