add test

Author: namrataghadi-galileo

sdks/python/tests/test_trace_context.py

@@ -29,6 +29,12 @@ def test_get_trace_context_from_provider_returns_none_when_unset() -> None:
     assert get_trace_context_from_provider() is None
 
 
+def test_get_trace_context_from_provider_returns_none_when_provider_returns_none() -> None:
+    set_trace_context_provider(lambda: None)
+
+    assert get_trace_context_from_provider() is None
+
+
 def test_get_trace_context_from_provider_swallows_provider_failures() -> None:
     def _raising_provider():
         raise RuntimeError("boom")