Added property resource_templates and reas_resource that were present in session but missing in session_group.

TESTED=unit tests

Author: AishwaryaKalloli

src/mcp/client/session_group.py

@@ -16,7 +16,7 @@
 from typing import Any, TypeAlias
 
 import anyio
-from pydantic import BaseModel
+from pydantic import BaseModel, AnyUrl
 from typing_extensions import Self
 
 import mcp
@@ -100,6 +100,7 @@ class _ComponentNames(BaseModel):
     # Client-server connection management.
     _sessions: dict[mcp.ClientSession, _ComponentNames]
     _tool_to_session: dict[str, mcp.ClientSession]
+    _resource_to_session: dict[str, mcp.ClientSession]
     _exit_stack: contextlib.AsyncExitStack
     _session_exit_stacks: dict[mcp.ClientSession, contextlib.AsyncExitStack]
 
@@ -116,20 +117,16 @@ def __init__(
     ) -> None:
         """Initializes the MCP client."""
 
-        self._tools = {}
-        self._resources = {}
+        self._exit_stack = exit_stack or contextlib.AsyncExitStack()
+        self._owns_exit_stack = exit_stack is None
+        self._session_exit_stacks = {}
+        self._component_name_hook = component_name_hook
         self._prompts = {}
-
+        self._resources = {}
+        self._tools = {}
         self._sessions = {}
         self._tool_to_session = {}
-        if exit_stack is None:
-            self._exit_stack = contextlib.AsyncExitStack()
-            self._owns_exit_stack = True
-        else:
-            self._exit_stack = exit_stack
-            self._owns_exit_stack = False
-        self._session_exit_stacks = {}
-        self._component_name_hook = component_name_hook
+        self._resource_to_session = {}  # New mapping
 
     async def __aenter__(self) -> Self:
         # Enter the exit stack only if we created it ourselves
@@ -174,6 +171,16 @@ def tools(self) -> dict[str, types.Tool]:
         """Returns the tools as a dictionary of names to tools."""
         return self._tools
 
+    @property
+    def resource_templates(self) -> list[types.ResourceTemplate]:
+        """Return all unique resource templates from the resources."""
+        templates: list[types.ResourceTemplate] = []
+        for r in self._resources.values():
+            t = getattr(r, "template", None)
+            if t is not None and t not in templates:
+                templates.append(t)
+        return templates
+
     async def call_tool(self, name: str, args: dict[str, Any]) -> types.CallToolResult:
         """Executes a tool given its name and arguments."""
         session = self._tool_to_session[name]
@@ -296,8 +303,8 @@ async def _aggregate_components(
         resources_temp: dict[str, types.Resource] = {}
         tools_temp: dict[str, types.Tool] = {}
         tool_to_session_temp: dict[str, mcp.ClientSession] = {}
+        resource_to_session_temp: dict[str, mcp.ClientSession] = {} 
 
-        # Query the server for its prompts and aggregate to list.
         try:
             prompts = (await session.list_prompts()).prompts
             for prompt in prompts:
@@ -314,6 +321,7 @@ async def _aggregate_components(
                 name = self._component_name(resource.name, server_info)
                 resources_temp[name] = resource
                 component_names.resources.add(name)
+                resource_to_session_temp[name] = session
         except McpError as err:
             logging.warning(f"Could not fetch resources: {err}")
 
@@ -365,8 +373,20 @@ async def _aggregate_components(
         self._resources.update(resources_temp)
         self._tools.update(tools_temp)
         self._tool_to_session.update(tool_to_session_temp)
+        self._resource_to_session.update(resource_to_session_temp)
 
     def _component_name(self, name: str, server_info: types.Implementation) -> str:
         if self._component_name_hook:
             return self._component_name_hook(name, server_info)
         return name
+
+    async def read_resource(self, uri: AnyUrl) -> types.ReadResourceResult:
+        """Read a resource from the appropriate session based on the URI."""
+        print(self._resources)
+        print(self._resource_to_session)
+        for name, resource in self._resources.items():
+            if resource.uri == uri:
+                session = self._resource_to_session.get(name)
+                if session:
+                    return await session.read_resource(uri)
+        raise ValueError(f"Resource not found: {uri}")

tests/client/test_session_group.py

@@ -2,6 +2,7 @@
 from unittest import mock
 
 import pytest
+from pydantic import AnyUrl
 
 import mcp
 from mcp import types
@@ -395,3 +396,73 @@ async def test_establish_session_parameterized(
                 # 3. Assert returned values
                 assert returned_server_info is mock_initialize_result.serverInfo
                 assert returned_session is mock_entered_session
+
+    @pytest.mark.anyio
+    async def test_read_resource_not_found(self):
+        """Test reading a non-existent resource from a session group."""
+        # --- Mock Dependencies ---
+        mock_session = mock.AsyncMock(spec=mcp.ClientSession)
+        test_resource = types.Resource(
+            name="test_resource",
+            uri=AnyUrl("test://resource/1"),
+            description="Test resource"
+        )
+        
+        # Mock all list methods
+        mock_session.list_resources.return_value = types.ListResourcesResult(resources=[test_resource])
+        mock_session.list_prompts.return_value = types.ListPromptsResult(prompts=[])
+        mock_session.list_tools.return_value = types.ListToolsResult(tools=[])
+        
+        # --- Test Setup ---
+        group = ClientSessionGroup()
+        group._session_exit_stacks[mock_session] = mock.AsyncMock(spec=contextlib.AsyncExitStack)
+        await group.connect_with_session(
+            types.Implementation(name="test_server", version="1.0.0"),
+            mock_session
+        )
+        
+        # --- Test Execution & Assertions ---
+        with pytest.raises(ValueError, match="Resource not found: test://nonexistent"):
+            await group.read_resource(AnyUrl("test://nonexistent"))
+
+    @pytest.mark.anyio
+    async def test_read_resource_success(self):
+        """Test successfully reading a resource from a session group."""
+        # --- Mock Dependencies ---
+        mock_session = mock.AsyncMock(spec=mcp.ClientSession)
+        test_resource = types.Resource(
+            name="test_resource",
+            uri=AnyUrl("test://resource/1"),
+            description="Test resource"
+        )
+        
+        # Mock all list methods
+        mock_session.list_resources.return_value = types.ListResourcesResult(resources=[test_resource])
+        mock_session.list_prompts.return_value = types.ListPromptsResult(prompts=[])
+        mock_session.list_tools.return_value = types.ListToolsResult(tools=[])
+        
+        # Mock the session's read_resource method
+        mock_read_result = mock.AsyncMock(spec=types.ReadResourceResult)
+        mock_read_result.content = [types.TextContent(type="text", text="Resource content")]
+        mock_session.read_resource.return_value = mock_read_result
+        
+        # --- Test Setup ---
+        group = ClientSessionGroup()
+        group._session_exit_stacks[mock_session] = mock.AsyncMock(spec=contextlib.AsyncExitStack)
+        await group.connect_with_session(
+            types.Implementation(name="test_server", version="1.0.0"),
+            mock_session
+        )
+        
+        # Verify resource was added
+        assert "test_resource" in group._resources
+        assert group._resources["test_resource"] == test_resource
+        assert "test_resource" in group._resource_to_session
+        assert group._resource_to_session["test_resource"] == mock_session
+        
+        # --- Test Execution ---
+        result = await group.read_resource(AnyUrl("test://resource/1"))
+        
+        # --- Assertions ---
+        assert result.content == [types.TextContent(type="text", text="Resource content")]
+        mock_session.read_resource.assert_called_once_with(AnyUrl("test://resource/1"))