feature: add support ResourceTemplates to mcptest package (#449)

Slach · web-flow · commit 251da138d6b5 · 2025-07-01T21:33:30.000+03:00
* feat: implement AddResourceTemplate and add resource template test * fix: use local ServerResourceTemplate type in mcptest * fix: replace NewURITemplate with UnmarshalText for URI template creation * fix: correct URITemplate unmarshaling and err variable declaration in tests * fix: improve resource template argument extraction in test handler * test: add assertions to verify URI template argument population * simplify TestServerWithResourceTemplate logic and increase test coverage * changes after code review #449 (comment)
diff --git a/mcptest/mcptest.go b/mcptest/mcptest.go
@@ -20,9 +20,10 @@ import (
 type Server struct {
 	name string
 
-	tools     []server.ServerTool
-	prompts   []server.ServerPrompt
-	resources []server.ServerResource
+	tools             []server.ServerTool
+	prompts           []server.ServerPrompt
+	resources         []server.ServerResource
+	resourceTemplates []ServerResourceTemplate
 
 	cancel func()
 
@@ -106,6 +107,25 @@ func (s *Server) AddResources(resources ...server.ServerResource) {
 	s.resources = append(s.resources, resources...)
 }
 
+// ServerResourceTemplate combines a ResourceTemplate with its handler function.
+type ServerResourceTemplate struct {
+	Template mcp.ResourceTemplate
+	Handler  server.ResourceTemplateHandlerFunc
+}
+
+// AddResourceTemplate adds a resource template to an unstarted server.
+func (s *Server) AddResourceTemplate(template mcp.ResourceTemplate, handler server.ResourceTemplateHandlerFunc) {
+	s.resourceTemplates = append(s.resourceTemplates, ServerResourceTemplate{
+		Template: template,
+		Handler:  handler,
+	})
+}
+
+// AddResourceTemplates adds multiple resource templates to an unstarted server.
+func (s *Server) AddResourceTemplates(templates ...ServerResourceTemplate) {
+	s.resourceTemplates = append(s.resourceTemplates, templates...)
+}
+
 // Start starts the server in a goroutine. Make sure to defer Close() after Start().
 // When using NewServer(), the returned server is already started.
 func (s *Server) Start(ctx context.Context) error {
@@ -122,6 +142,10 @@ func (s *Server) Start(ctx context.Context) error {
 		mcpServer.AddTools(s.tools...)
 		mcpServer.AddPrompts(s.prompts...)
 		mcpServer.AddResources(s.resources...)
+		
+		for _, template := range s.resourceTemplates {
+			mcpServer.AddResourceTemplate(template.Template, template.Handler)
+		}
 
 		logger := log.New(&s.logBuffer, "", 0)
 
diff --git a/mcptest/mcptest_test.go b/mcptest/mcptest_test.go
@@ -187,3 +187,79 @@ func TestServerWithResource(t *testing.T) {
 		t.Errorf("Got %q, want %q", textContent.Text, want)
 	}
 }
+
+func TestServerWithResourceTemplate(t *testing.T) {
+	ctx := context.Background()
+
+	srv := mcptest.NewUnstartedServer(t)
+	defer srv.Close()
+
+	template := mcp.NewResourceTemplate(
+		"file://users/{userId}/documents/{docId}",
+		"User Document",
+		mcp.WithTemplateDescription("A user's document"),
+		mcp.WithTemplateMIMEType("text/plain"),
+	)
+
+	handler := func(ctx context.Context, request mcp.ReadResourceRequest) ([]mcp.ResourceContents, error) {
+		if request.Params.Arguments == nil {
+			return nil, fmt.Errorf("expected arguments to be populated from URI template")
+		}
+
+		userIds, ok := request.Params.Arguments["userId"].([]string)
+		if !ok {
+			return nil, fmt.Errorf("expected userId argument to be populated from URI template")
+		}
+		if len(userIds) != 1 {
+			return nil, fmt.Errorf("expected userId to have one value, but got %d", len(userIds))
+		}
+		if userIds[0] != "john" {
+			return nil, fmt.Errorf("expected userId argument to be 'john', got %s", userIds[0])
+		}
+
+		docIds, ok := request.Params.Arguments["docId"].([]string)
+		if !ok {
+			return nil, fmt.Errorf("expected docId argument to be populated from URI template")
+		}
+		if len(docIds) != 1 {
+			return nil, fmt.Errorf("expected docId to have one value, but got %d", len(docIds))
+		}
+		if docIds[0] != "readme.txt" {
+			return nil, fmt.Errorf("expected docId argument to be 'readme.txt', got %v", docIds)
+		}
+
+		return []mcp.ResourceContents{
+			mcp.TextResourceContents{
+				URI:      request.Params.URI,
+				MIMEType: "text/plain",
+				Text:     fmt.Sprintf("Document %s for user %s", docIds[0], userIds[0]),
+			},
+		}, nil
+	}
+
+	srv.AddResourceTemplate(template, handler)
+
+	err := srv.Start(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Test reading a resource that matches the template
+	var readReq mcp.ReadResourceRequest
+	readReq.Params.URI = "file://users/john/documents/readme.txt"
+	readResult, err := srv.Client().ReadResource(ctx, readReq)
+	if err != nil {
+		t.Fatal("ReadResource:", err)
+	}
+	if len(readResult.Contents) != 1 {
+		t.Fatalf("Expected 1 content, got %d", len(readResult.Contents))
+	}
+	textContent, ok := readResult.Contents[0].(mcp.TextResourceContents)
+	if !ok {
+		t.Fatalf("Expected TextResourceContents, got %T", readResult.Contents[0])
+	}
+	want := "Document readme.txt for user john"
+	if textContent.Text != want {
+		t.Errorf("Got %q, want %q", textContent.Text, want)
+	}
+}
