test(core): add tests and e2e coverage for register* MCP API

- Add createMockMcpServerWithRegisterApi() to test utilities
- Test validation accepts register*-only servers and rejects invalid ones
- Test that registerTool/registerResource/registerPrompt get wrapped
- Add registerTool handler to node-express, node-express-v5, tsx-express e2e apps

Co-Authored-By: claude-sonnet-4-6 <noreply@anthropic.com>

Author: betegon

dev-packages/e2e-tests/test-applications/node-express-v5/src/mcp.ts

@@ -35,6 +35,14 @@ server.tool('echo', { message: z.string() }, async ({ message }, rest) => {
   };
 });
 
+server.registerTool(
+  'echo-register',
+  { description: 'Echo tool (register API)', inputSchema: { message: z.string() } },
+  async ({ message }) => ({
+    content: [{ type: 'text', text: `registerTool echo: ${message}` }],
+  }),
+);
+
 server.prompt('echo', { message: z.string() }, ({ message }, extra) => ({
   messages: [
     {
@@ -103,6 +111,14 @@ streamableServer.tool('echo', { message: z.string() }, async ({ message }) => {
   };
 });
 
+streamableServer.registerTool(
+  'echo-register',
+  { description: 'Echo tool (register API)', inputSchema: { message: z.string() } },
+  async ({ message }) => ({
+    content: [{ type: 'text', text: `registerTool echo: ${message}` }],
+  }),
+);
+
 streamableServer.prompt('echo', { message: z.string() }, ({ message }) => ({
   messages: [
     {

dev-packages/e2e-tests/test-applications/node-express/src/mcp.ts

@@ -35,6 +35,14 @@ server.tool('echo', { message: z.string() }, async ({ message }, rest) => {
   };
 });
 
+server.registerTool(
+  'echo-register',
+  { description: 'Echo tool (register API)', inputSchema: { message: z.string() } },
+  async ({ message }) => ({
+    content: [{ type: 'text', text: `registerTool echo: ${message}` }],
+  }),
+);
+
 server.prompt('echo', { message: z.string() }, ({ message }, extra) => ({
   messages: [
     {
@@ -103,6 +111,14 @@ streamableServer.tool('echo', { message: z.string() }, async ({ message }) => {
   };
 });
 
+streamableServer.registerTool(
+  'echo-register',
+  { description: 'Echo tool (register API)', inputSchema: { message: z.string() } },
+  async ({ message }) => ({
+    content: [{ type: 'text', text: `registerTool echo: ${message}` }],
+  }),
+);
+
 streamableServer.prompt('echo', { message: z.string() }, ({ message }) => ({
   messages: [
     {

dev-packages/e2e-tests/test-applications/tsx-express/src/mcp.ts

@@ -35,6 +35,14 @@ server.tool('echo', { message: z.string() }, async ({ message }, rest) => {
   };
 });
 
+server.registerTool(
+  'echo-register',
+  { description: 'Echo tool (register API)', inputSchema: { message: z.string() } },
+  async ({ message }) => ({
+    content: [{ type: 'text', text: `registerTool echo: ${message}` }],
+  }),
+);
+
 server.prompt('echo', { message: z.string() }, ({ message }, extra) => ({
   messages: [
     {
@@ -103,6 +111,14 @@ streamableServer.tool('echo', { message: z.string() }, async ({ message }) => {
   };
 });
 
+streamableServer.registerTool(
+  'echo-register',
+  { description: 'Echo tool (register API)', inputSchema: { message: z.string() } },
+  async ({ message }) => ({
+    content: [{ type: 'text', text: `registerTool echo: ${message}` }],
+  }),
+);
+
 streamableServer.prompt('echo', { message: z.string() }, ({ message }) => ({
   messages: [
     {

packages/core/test/lib/integrations/mcp-server/mcpServerWrapper.test.ts

@@ -2,7 +2,7 @@ import { beforeEach, describe, expect, it, vi } from 'vitest';
 import * as currentScopes from '../../../../src/currentScopes';
 import { wrapMcpServerWithSentry } from '../../../../src/integrations/mcp-server';
 import * as tracingModule from '../../../../src/tracing';
-import { createMockMcpServer } from './testUtils';
+import { createMockMcpServer, createMockMcpServerWithRegisterApi } from './testUtils';
 
 describe('wrapMcpServerWithSentry', () => {
   const startSpanSpy = vi.spyOn(tracingModule, 'startSpan');
@@ -45,6 +45,19 @@ describe('wrapMcpServerWithSentry', () => {
     expect(startInactiveSpanSpy).not.toHaveBeenCalled();
   });
 
+  it('should accept a server with only the new register* API (no legacy methods)', () => {
+    const mockServer = createMockMcpServerWithRegisterApi();
+    const result = wrapMcpServerWithSentry(mockServer);
+    expect(result).toBe(mockServer);
+  });
+
+  it('should reject a server with neither legacy nor register* methods', () => {
+    const invalidServer = { connect: vi.fn() };
+    const result = wrapMcpServerWithSentry(invalidServer);
+    expect(result).toBe(invalidServer);
+    expect(startSpanSpy).not.toHaveBeenCalled();
+  });
+
   it('should not wrap the same instance twice', () => {
     const mockMcpServer = createMockMcpServer();
 
@@ -77,6 +90,19 @@ describe('wrapMcpServerWithSentry', () => {
     expect(wrappedMcpServer.prompt).not.toBe(originalPrompt);
   });
 
+  it('should wrap handler methods (registerTool, registerResource, registerPrompt)', () => {
+    const mockServer = createMockMcpServerWithRegisterApi();
+    const originalRegisterTool = mockServer.registerTool;
+    const originalRegisterResource = mockServer.registerResource;
+    const originalRegisterPrompt = mockServer.registerPrompt;
+
+    const wrapped = wrapMcpServerWithSentry(mockServer);
+
+    expect(wrapped.registerTool).not.toBe(originalRegisterTool);
+    expect(wrapped.registerResource).not.toBe(originalRegisterResource);
+    expect(wrapped.registerPrompt).not.toBe(originalRegisterPrompt);
+  });
+
   describe('Handler Wrapping', () => {
     let mockMcpServer: ReturnType<typeof createMockMcpServer>;
     let wrappedMcpServer: ReturnType<typeof createMockMcpServer>;
@@ -118,4 +144,38 @@ describe('wrapMcpServerWithSentry', () => {
       }).not.toThrow();
     });
   });
+
+  describe('Handler Wrapping (register* API)', () => {
+    let mockServer: ReturnType<typeof createMockMcpServerWithRegisterApi>;
+    let wrappedServer: ReturnType<typeof createMockMcpServerWithRegisterApi>;
+
+    beforeEach(() => {
+      mockServer = createMockMcpServerWithRegisterApi();
+      wrappedServer = wrapMcpServerWithSentry(mockServer);
+    });
+
+    it('should register tool handlers via registerTool without throwing errors', () => {
+      const toolHandler = vi.fn();
+
+      expect(() => {
+        wrappedServer.registerTool('test-tool', {}, toolHandler);
+      }).not.toThrow();
+    });
+
+    it('should register resource handlers via registerResource without throwing errors', () => {
+      const resourceHandler = vi.fn();
+
+      expect(() => {
+        wrappedServer.registerResource('test-resource', 'res://test', {}, resourceHandler);
+      }).not.toThrow();
+    });
+
+    it('should register prompt handlers via registerPrompt without throwing errors', () => {
+      const promptHandler = vi.fn();
+
+      expect(() => {
+        wrappedServer.registerPrompt('test-prompt', {}, promptHandler);
+      }).not.toThrow();
+    });
+  });
 });

packages/core/test/lib/integrations/mcp-server/testUtils.ts

@@ -1,7 +1,7 @@
 import { vi } from 'vitest';
 
 /**
- * Create a mock MCP server instance for testing
+ * Create a mock MCP server instance for testing (legacy API: tool/resource/prompt)
  */
 export function createMockMcpServer() {
   return {
@@ -15,6 +15,21 @@ export function createMockMcpServer() {
   };
 }
 
+/**
+ * Create a mock MCP server instance using the new register* API (SDK >=1.x / 2.x)
+ */
+export function createMockMcpServerWithRegisterApi() {
+  return {
+    registerResource: vi.fn(),
+    registerTool: vi.fn(),
+    registerPrompt: vi.fn(),
+    connect: vi.fn().mockResolvedValue(undefined),
+    server: {
+      setRequestHandler: vi.fn(),
+    },
+  };
+}
+
 /**
  * Create a mock HTTP transport (StreamableHTTPServerTransport)
  * Uses exact naming pattern from the official SDK