Add UV Transport (#1270)

Co-authored-by: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>

tests/client/transports/test_uv_transport.py

@@ -0,0 +1,98 @@
+import inspect
+import sys
+import tempfile
+from pathlib import Path
+
+import pytest
+
+from fastmcp.client import Client
+from fastmcp.client.client import CallToolResult
+from fastmcp.client.transports import (
+    UvStdioTransport,
+)
+
+
+@pytest.mark.timeout(10)
+@pytest.mark.client_process
+@pytest.mark.skipif(
+    sys.platform == "win32",
+    reason="Windows file locking issues with uv client process cleanup",
+)
+async def test_uv_transport():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        script: str = inspect.cleandoc('''
+            from fastmcp import FastMCP
+
+            mcp = FastMCP()
+
+            @mcp.tool
+            def add(x: int, y: int) -> int:
+                """Adds two numbers together"""
+                return x + y
+
+            if __name__ == "__main__":
+                mcp.run()
+            ''')
+        script_file: Path = Path(tmpdir) / "uv.py"
+        _ = script_file.write_text(script)
+
+        client: Client[UvStdioTransport] = Client(
+            transport=UvStdioTransport(command=str(script_file), keep_alive=False)
+        )
+
+        async with client:
+            result: CallToolResult = await client.call_tool("add", {"x": 1, "y": 2})
+            sum: int = result.data  # pyright: ignore[reportAny]
+
+        # Explicitly close the transport to ensure subprocess cleanup
+        await client.transport.close()
+        assert sum == 3
+
+
+@pytest.mark.timeout(10)
+@pytest.mark.client_process
+@pytest.mark.skipif(
+    sys.platform == "win32",
+    reason="Windows file locking issues with uv client process cleanup",
+)
+async def test_uv_transport_module():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        module_dir = Path(tmpdir) / "my_module"
+        module_dir.mkdir()
+        module_script = inspect.cleandoc('''
+            from fastmcp import FastMCP
+
+            mcp = FastMCP()
+
+            @mcp.tool
+            def add(x: int, y: int) -> int:
+                """Adds two numbers together"""
+                return x + y
+            ''')
+        script_file: Path = module_dir / "module.py"
+        _ = script_file.write_text(module_script)
+
+        main_script: str = inspect.cleandoc("""
+            from .module import mcp
+            mcp.run()
+        """)
+        main_file = module_dir / "__main__.py"
+        _ = main_file.write_text(main_script)
+
+        client: Client[UvStdioTransport] = Client(
+            transport=UvStdioTransport(
+                with_packages=["fastmcp"],
+                command="my_module",
+                module=True,
+                project_directory=tmpdir,
+                keep_alive=False,
+            )
+        )
+
+        async with client:
+            result: CallToolResult = await client.call_tool("add", {"x": 1, "y": 2})
+            sum: int = result.data  # pyright: ignore[reportAny]
+
+        # Explicitly close the transport to ensure subprocess cleanup
+        await client.transport.close()
+        assert sum == 3