test(callbacks): cover upstream langfuse debug env

tests/logging_callback_tests/test_langfuse_dynamic_credentials.py

@@ -1,3 +1,7 @@
+import sys
+from types import ModuleType, SimpleNamespace
+
+import litellm
 from litellm.integrations.langfuse.langfuse import resolve_langfuse_credentials
 
 
@@ -44,3 +48,36 @@ def test_resolve_langfuse_credentials_keeps_env_for_global_config(monkeypatch):
     assert public_key == "global-public"
     assert secret_key == "global-secret"
     assert host == "https://admin-configured.example"
+
+
+def test_upstream_langfuse_debug_env_is_passed(monkeypatch):
+    from litellm.integrations.langfuse.langfuse import LangFuseLogger
+
+    class FakeLangfuse:
+        instances = []
+
+        def __init__(self, **kwargs):
+            self.kwargs = kwargs
+            FakeLangfuse.instances.append(self)
+
+    fake_langfuse_module = ModuleType("langfuse")
+    fake_langfuse_module.Langfuse = FakeLangfuse
+    fake_langfuse_module.version = SimpleNamespace(__version__="2.6.0")
+
+    monkeypatch.setitem(sys.modules, "langfuse", fake_langfuse_module)
+    monkeypatch.setattr(litellm, "initialized_langfuse_clients", 0)
+    monkeypatch.setenv("LANGFUSE_MOCK", "true")
+    monkeypatch.setenv("UPSTREAM_LANGFUSE_SECRET_KEY", "upstream-secret")
+    monkeypatch.setenv("UPSTREAM_LANGFUSE_PUBLIC_KEY", "upstream-public")
+    monkeypatch.setenv("UPSTREAM_LANGFUSE_HOST", "https://upstream.example")
+    monkeypatch.setenv("UPSTREAM_LANGFUSE_RELEASE", "release")
+    monkeypatch.setenv("UPSTREAM_LANGFUSE_DEBUG", "true")
+
+    logger = LangFuseLogger(
+        langfuse_public_key="public",
+        langfuse_secret="secret",
+        langfuse_host="https://langfuse.example",
+    )
+
+    assert logger.upstream_langfuse_debug == "true"
+    assert FakeLangfuse.instances[-1].kwargs["debug"] is True