Testing: use synctest for timing-dependent tests

examples/server/auth-middleware/go.mod

@@ -8,7 +8,7 @@ require (
 )
 
 require (
-	github.com/google/jsonschema-go v0.3.0 // indirect
+	github.com/google/jsonschema-go v0.4.2 // indirect
 	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
 	golang.org/x/oauth2 v0.30.0 // indirect
 )

examples/server/auth-middleware/go.sum

@@ -4,6 +4,7 @@ github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/google/jsonschema-go v0.3.0 h1:6AH2TxVNtk3IlvkkhjrtbUc4S8AvO0Xii0DxIygDg+Q=
 github.com/google/jsonschema-go v0.3.0/go.mod h1:r5quNTdLOYEz95Ru18zA0ydNbBuYoo9tgaYcxEYhJVE=
+github.com/google/jsonschema-go v0.4.2/go.mod h1:r5quNTdLOYEz95Ru18zA0ydNbBuYoo9tgaYcxEYhJVE=
 github.com/yosida95/uritemplate/v3 v3.0.2 h1:Ed3Oyj9yrmi9087+NczuL5BwkIc4wvTb5zIM+UJPGz4=
 github.com/yosida95/uritemplate/v3 v3.0.2/go.mod h1:ILOh0sOhIJR3+L/8afwt/kE++YT040gmv5BQTMR2HP4=
 golang.org/x/oauth2 v0.30.0 h1:dnDm7JmhM45NNpd8FDDeLhK6FwqbOf4MLCM9zb1BOHI=

examples/server/rate-limiting/go.mod

@@ -8,7 +8,7 @@ require (
 )
 
 require (
-	github.com/google/jsonschema-go v0.3.0 // indirect
+	github.com/google/jsonschema-go v0.4.2 // indirect
 	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
 )
 

examples/server/rate-limiting/go.sum

@@ -2,6 +2,7 @@ github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/google/jsonschema-go v0.3.0 h1:6AH2TxVNtk3IlvkkhjrtbUc4S8AvO0Xii0DxIygDg+Q=
 github.com/google/jsonschema-go v0.3.0/go.mod h1:r5quNTdLOYEz95Ru18zA0ydNbBuYoo9tgaYcxEYhJVE=
+github.com/google/jsonschema-go v0.4.2/go.mod h1:r5quNTdLOYEz95Ru18zA0ydNbBuYoo9tgaYcxEYhJVE=
 github.com/yosida95/uritemplate/v3 v3.0.2 h1:Ed3Oyj9yrmi9087+NczuL5BwkIc4wvTb5zIM+UJPGz4=
 github.com/yosida95/uritemplate/v3 v3.0.2/go.mod h1:ILOh0sOhIJR3+L/8afwt/kE++YT040gmv5BQTMR2HP4=
 golang.org/x/time v0.12.0 h1:ScB/8o8olJvc+CQPWrK3fPZNfh7qgwCrY0zJmoEQLSE=

mcp/cmd_go125_test.go

@@ -0,0 +1,57 @@
+// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.25
+
+package mcp_test
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"testing/synctest"
+
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
+
+func TestServerRunContextCancel(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
+		server := mcp.NewServer(&mcp.Implementation{Name: "greeter", Version: "v0.0.1"}, nil)
+		mcp.AddTool(server, &mcp.Tool{Name: "greet", Description: "say hi"}, SayHi)
+
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+
+		serverTransport, clientTransport := mcp.NewInMemoryTransports()
+
+		// run the server and capture the exit error
+		onServerExit := make(chan error)
+		go func() {
+			onServerExit <- server.Run(ctx, serverTransport)
+		}()
+
+		// send a ping to the server to ensure it's running
+		client := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
+		session, err := client.Connect(ctx, clientTransport, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		t.Cleanup(func() { session.Close() })
+
+		if err := session.Ping(context.Background(), nil); err != nil {
+			t.Fatal(err)
+		}
+
+		// cancel the context to stop the server
+		cancel()
+
+		// wait for the server to exit
+		// synctest will detect deadlock if server doesn't exit
+		synctest.Wait()
+		err = <-onServerExit
+		if !errors.Is(err, context.Canceled) {
+			t.Fatalf("server did not exit after context cancellation, got error: %v", err)
+		}
+	})
+}

mcp/cmd_test.go

@@ -76,48 +76,6 @@ func runCancelContextServer() {
 	}
 }
 
-func TestServerRunContextCancel(t *testing.T) {
-	server := mcp.NewServer(&mcp.Implementation{Name: "greeter", Version: "v0.0.1"}, nil)
-	mcp.AddTool(server, &mcp.Tool{Name: "greet", Description: "say hi"}, SayHi)
-
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	serverTransport, clientTransport := mcp.NewInMemoryTransports()
-
-	// run the server and capture the exit error
-	onServerExit := make(chan error)
-	go func() {
-		onServerExit <- server.Run(ctx, serverTransport)
-	}()
-
-	// send a ping to the server to ensure it's running
-	client := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
-	session, err := client.Connect(ctx, clientTransport, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
-	t.Cleanup(func() { session.Close() })
-
-	if err := session.Ping(context.Background(), nil); err != nil {
-		t.Fatal(err)
-	}
-
-	// cancel the context to stop the server
-	cancel()
-
-	// wait for the server to exit
-	// TODO: use synctest when availble
-	select {
-	case <-time.After(5 * time.Second):
-		t.Fatal("server did not exit after context cancellation")
-	case err := <-onServerExit:
-		if !errors.Is(err, context.Canceled) {
-			t.Fatalf("server did not exit after context cancellation, got error: %v", err)
-		}
-	}
-}
-
 func TestServerInterrupt(t *testing.T) {
 	if runtime.GOOS == "windows" {
 		t.Skip("requires POSIX signals")

mcp/elicitation_go125_test.go

@@ -0,0 +1,71 @@
+// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.25
+
+package mcp
+
+import (
+	"context"
+	"testing"
+	"testing/synctest"
+)
+
+func TestElicitationCompleteNotification(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
+		ctx := context.Background()
+
+		var elicitationCompleteCh = make(chan *ElicitationCompleteParams, 1)
+
+		c := NewClient(testImpl, &ClientOptions{
+			Capabilities: &ClientCapabilities{
+				Roots:   RootCapabilities{ListChanged: true},
+				RootsV2: &RootCapabilities{ListChanged: true},
+				Elicitation: &ElicitationCapabilities{
+					URL: &URLElicitationCapabilities{},
+				},
+			},
+			ElicitationHandler: func(context.Context, *ElicitRequest) (*ElicitResult, error) {
+				return &ElicitResult{Action: "accept"}, nil
+			},
+			ElicitationCompleteHandler: func(_ context.Context, req *ElicitationCompleteNotificationRequest) {
+				elicitationCompleteCh <- req.Params
+			},
+		})
+
+		cs, ss, cleanup := basicClientServerConnection(t, c, nil, nil)
+		_ = cs // Dummy usage to avoid "declared and not used" error.
+		defer cleanup()
+
+		// 1. Server initiates a URL elicitation
+		elicitID := "testElicitationID-123"
+		resp, err := ss.Elicit(ctx, &ElicitParams{
+			Mode:          "url",
+			Message:       "Please complete this form: ",
+			URL:           "https://example.com/form?id=" + elicitID,
+			ElicitationID: elicitID,
+		})
+		if err != nil {
+			t.Fatalf("Elicit failed: %v", err)
+		}
+		if resp.Action != "accept" {
+			t.Fatalf("Elicit action is %q, want %q", resp.Action, "accept")
+		}
+
+		// 2. Server sends elicitation complete notification (simulating out-of-band completion)
+		err = handleNotify(ctx, notificationElicitationComplete, newServerRequest(ss, &ElicitationCompleteParams{
+			ElicitationID: elicitID,
+		}))
+		if err != nil {
+			t.Fatalf("failed to send elicitation complete notification: %v", err)
+		}
+
+		// 3. Client should receive the notification
+		synctest.Wait()
+		gotParams := <-elicitationCompleteCh
+		if gotParams.ElicitationID != elicitID {
+			t.Errorf("elicitationComplete notification ID mismatch: got %q, want %q", gotParams.ElicitationID, elicitID)
+		}
+	})
+}

mcp/elicitation_test.go

@@ -9,7 +9,6 @@ import (
 	"errors"
 	"strings"
 	"testing"
-	"time"
 
 	"github.com/google/jsonschema-go/jsonschema"
 	"github.com/modelcontextprotocol/go-sdk/jsonrpc"
@@ -142,62 +141,3 @@ func TestElicitationURLMode(t *testing.T) {
 		})
 	}
 }
-
-func TestElicitationCompleteNotification(t *testing.T) {
-	ctx := context.Background()
-
-	var elicitationCompleteCh = make(chan *ElicitationCompleteParams, 1)
-
-	c := NewClient(testImpl, &ClientOptions{
-		Capabilities: &ClientCapabilities{
-			Roots:   RootCapabilities{ListChanged: true},
-			RootsV2: &RootCapabilities{ListChanged: true},
-			Elicitation: &ElicitationCapabilities{
-				URL: &URLElicitationCapabilities{},
-			},
-		},
-		ElicitationHandler: func(context.Context, *ElicitRequest) (*ElicitResult, error) {
-			return &ElicitResult{Action: "accept"}, nil
-		},
-		ElicitationCompleteHandler: func(_ context.Context, req *ElicitationCompleteNotificationRequest) {
-			elicitationCompleteCh <- req.Params
-		},
-	})
-
-	cs, ss, cleanup := basicClientServerConnection(t, c, nil, nil)
-	_ = cs // Dummy usage to avoid "declared and not used" error.
-	defer cleanup()
-
-	// 1. Server initiates a URL elicitation
-	elicitID := "testElicitationID-123"
-	resp, err := ss.Elicit(ctx, &ElicitParams{
-		Mode:          "url",
-		Message:       "Please complete this form: ",
-		URL:           "https://example.com/form?id=" + elicitID,
-		ElicitationID: elicitID,
-	})
-	if err != nil {
-		t.Fatalf("Elicit failed: %v", err)
-	}
-	if resp.Action != "accept" {
-		t.Fatalf("Elicit action is %q, want %q", resp.Action, "accept")
-	}
-
-	// 2. Server sends elicitation complete notification (simulating out-of-band completion)
-	err = handleNotify(ctx, notificationElicitationComplete, newServerRequest(ss, &ElicitationCompleteParams{
-		ElicitationID: elicitID,
-	}))
-	if err != nil {
-		t.Fatalf("failed to send elicitation complete notification: %v", err)
-	}
-
-	// 3. Client should receive the notification
-	select {
-	case gotParams := <-elicitationCompleteCh:
-		if gotParams.ElicitationID != elicitID {
-			t.Errorf("elicitationComplete notification ID mismatch: got %q, want %q", gotParams.ElicitationID, elicitID)
-		}
-	case <-time.After(5 * time.Second):
-		t.Fatal("timed out waiting for elicitation complete notification")
-	}
-}