Fix circular reference JSON serialization in telemetry logging (#4150)

packages/core/src/telemetry/loggers.test.circular.ts

@@ -0,0 +1,119 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * Test to verify circular reference handling in telemetry logging
+ */
+
+import { describe, it, expect } from 'vitest';
+import { logToolCall } from './loggers.js';
+import { ToolCallEvent } from './types.js';
+import { Config } from '../config/config.js';
+import { CompletedToolCall } from '../core/coreToolScheduler.js';
+import { ToolCallRequestInfo, ToolCallResponseInfo } from '../core/turn.js';
+import { Tool } from '../tools/tools.js';
+
+describe('Circular Reference Handling', () => {
+  it('should handle circular references in tool function arguments', () => {
+    // Create a mock config
+    const mockConfig = {
+      getTelemetryEnabled: () => true,
+      getUsageStatisticsEnabled: () => true,
+      getSessionId: () => 'test-session',
+      getModel: () => 'test-model',
+      getEmbeddingModel: () => 'test-embedding',
+      getDebugMode: () => false,
+    } as unknown as Config;
+
+    // Create an object with circular references (similar to HttpsProxyAgent)
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    const circularObject: any = {
+      sockets: {},
+      agent: null,
+    };
+    circularObject.agent = circularObject; // Create circular reference
+    circularObject.sockets['test-host'] = [
+      { _httpMessage: { agent: circularObject } },
+    ];
+
+    // Create a mock CompletedToolCall with circular references in function_args
+    const mockRequest: ToolCallRequestInfo = {
+      callId: 'test-call-id',
+      name: 'ReadFile',
+      args: circularObject, // This would cause the original error
+      isClientInitiated: false,
+      prompt_id: 'test-prompt-id',
+    };
+
+    const mockResponse: ToolCallResponseInfo = {
+      callId: 'test-call-id',
+      responseParts: [{ text: 'test result' }],
+      resultDisplay: undefined,
+      error: undefined, // undefined means success
+    };
+
+    const mockCompletedToolCall: CompletedToolCall = {
+      status: 'success',
+      request: mockRequest,
+      response: mockResponse,
+      tool: {} as Tool,
+      durationMs: 100,
+    };
+
+    // Create a tool call event with circular references in function_args
+    const event = new ToolCallEvent(mockCompletedToolCall);
+
+    // This should not throw an error
+    expect(() => {
+      logToolCall(mockConfig, event);
+    }).not.toThrow();
+  });
+
+  it('should handle normal objects without circular references', () => {
+    const mockConfig = {
+      getTelemetryEnabled: () => true,
+      getUsageStatisticsEnabled: () => true,
+      getSessionId: () => 'test-session',
+      getModel: () => 'test-model',
+      getEmbeddingModel: () => 'test-embedding',
+      getDebugMode: () => false,
+    } as unknown as Config;
+
+    const normalObject = {
+      filePath: '/test/path',
+      options: { encoding: 'utf8' },
+    };
+
+    const mockRequest: ToolCallRequestInfo = {
+      callId: 'test-call-id',
+      name: 'ReadFile',
+      args: normalObject,
+      isClientInitiated: false,
+      prompt_id: 'test-prompt-id',
+    };
+
+    const mockResponse: ToolCallResponseInfo = {
+      callId: 'test-call-id',
+      responseParts: [{ text: 'test result' }],
+      resultDisplay: undefined,
+      error: undefined, // undefined means success
+    };
+
+    const mockCompletedToolCall: CompletedToolCall = {
+      status: 'success',
+      request: mockRequest,
+      response: mockResponse,
+      tool: {} as Tool,
+      durationMs: 100,
+    };
+
+    const event = new ToolCallEvent(mockCompletedToolCall);
+
+    expect(() => {
+      logToolCall(mockConfig, event);
+    }).not.toThrow();
+  });
+});