feat: add PostHog mock client support

- Create posthog_mock_client.py using factory pattern
- Integrate mock client into PostHogLogger with mock mode detection
- Add verbose logging for mock mode initialization and batch operations
- Enable mock mode via POSTHOG_MOCK environment variable

litellm/integrations/posthog.py

@@ -17,6 +17,10 @@ from typing import Any, Dict, Optional, Tuple
 from litellm._logging import verbose_logger
 from litellm._uuid import uuid
 from litellm.integrations.custom_batch_logger import CustomBatchLogger
+from litellm.integrations.posthog_mock_client import (
+    should_use_posthog_mock,
+    create_mock_posthog_client,
+)
 from litellm.llms.custom_httpx.http_handler import (
     _get_httpx_client,
     get_async_httpx_client,
@@ -40,6 +44,12 @@ class PostHogLogger(CustomBatchLogger):
         """
         try:
             verbose_logger.debug("PostHog: in init posthog logger")
+            
+            self.is_mock_mode = should_use_posthog_mock()
+            if self.is_mock_mode:
+                create_mock_posthog_client()
+                verbose_logger.debug("[POSTHOG MOCK] PostHog logger initialized in mock mode")
+            
             if os.getenv("POSTHOG_API_KEY", None) is None:
                 raise Exception("POSTHOG_API_KEY is not set, set 'POSTHOG_API_KEY=<>'")
 
@@ -100,7 +110,10 @@ class PostHogLogger(CustomBatchLogger):
                     f"Response from PostHog API status_code: {response.status_code}, text: {response.text}"
                 )
 
-            verbose_logger.debug("PostHog: Sync event successfully sent")
+            if self.is_mock_mode:
+                verbose_logger.debug("[POSTHOG MOCK] Sync event successfully mocked")
+            else:
+                verbose_logger.debug("PostHog: Sync event successfully sent")
 
         except Exception as e:
             verbose_logger.exception(f"PostHog Sync Layer Error - {str(e)}")
@@ -320,6 +333,9 @@ class PostHogLogger(CustomBatchLogger):
             verbose_logger.debug(
                 f"PostHog: Sending batch of {len(self.log_queue)} events"
             )
+            
+            if self.is_mock_mode:
+                verbose_logger.debug("[POSTHOG MOCK] Mock mode enabled - API calls will be intercepted")
 
             # Group events by credentials for batch sending
             batches_by_credentials: Dict[tuple[str, str], list] = {}
@@ -350,9 +366,12 @@ class PostHogLogger(CustomBatchLogger):
                         f"Response from PostHog API status_code: {response.status_code}, text: {response.text}"
                     )
 
-            verbose_logger.debug(
-                f"PostHog: Batch of {len(self.log_queue)} events successfully sent"
-            )
+            if self.is_mock_mode:
+                verbose_logger.debug(f"[POSTHOG MOCK] Batch of {len(self.log_queue)} events successfully mocked")
+            else:
+                verbose_logger.debug(
+                    f"PostHog: Batch of {len(self.log_queue)} events successfully sent"
+                )
         except Exception as e:
             verbose_logger.exception(f"PostHog Error sending batch API - {str(e)}")
 
@@ -429,9 +448,14 @@ class PostHogLogger(CustomBatchLogger):
                         f"PostHog: Failed to flush on exit - status {response.status_code}"
                     )
 
-            verbose_logger.debug(
-                f"PostHog: Successfully flushed {len(self.log_queue)} events on exit"
-            )
+            if self.is_mock_mode:
+                verbose_logger.debug(
+                    f"[POSTHOG MOCK] Successfully flushed {len(self.log_queue)} events on exit"
+                )
+            else:
+                verbose_logger.debug(
+                    f"PostHog: Successfully flushed {len(self.log_queue)} events on exit"
+                )
             self.log_queue.clear()
 
         except Exception as e:

litellm/integrations/posthog_mock_client.py

@@ -0,0 +1,30 @@
+"""
+Mock httpx client for PostHog integration testing.
+
+This module intercepts PostHog API calls and returns successful mock responses,
+allowing full code execution without making actual network calls.
+
+Usage:
+    Set POSTHOG_MOCK=true in environment variables or config to enable mock mode.
+"""
+
+from litellm.integrations.mock_client_factory import MockClientConfig, create_mock_client_factory
+
+# Create mock client using factory
+_config = MockClientConfig(
+    name="POSTHOG",
+    env_var="POSTHOG_MOCK",
+    default_latency_ms=100,
+    default_status_code=200,
+    default_json_data={"status": "success"},
+    url_matchers=[
+        ".posthog.com",
+        "posthog.com",
+        "us.i.posthog.com",
+        "app.posthog.com",
+    ],
+    patch_async_handler=True,
+    patch_sync_client=True,
+)
+
+create_mock_posthog_client, should_use_posthog_mock = create_mock_client_factory(_config)