test: validate empty propagators for OTEL_PROPAGATORS="none"

opentelemetry-api/tests/propagators/test_propagators.py

@@ -52,14 +52,21 @@ def test_propagators(propagators):
     @patch.dict(environ, {OTEL_PROPAGATORS: "none"})
     @patch("opentelemetry.propagators.composite.CompositePropagator")
     def test_no_propagators_loaded(self, mock_compositehttppropagator):
-        def test_propagators(propagators):
-            self.assertEqual(
-                propagators, []
-            )  # Expecting an empty list of propagators
+        # Verify if exception is raised without the fix
+        with self.assertRaises(Exception):
+            from opentelemetry.propagate import get_global_textmap
 
-        mock_compositehttppropagator.configure_mock(
-            **{"side_effect": test_propagators}
-        )
+            get_global_textmap()
+
+        # Apply fix and verify propagators is empty, with no exception raised
+        try:
+            from opentelemetry.propagate import get_global_textmap
+
+            mock_compositehttppropagator.assert_called_with(
+                []
+            )  # Validate empty list of propagators
+        except Exception as e:
+            self.fail(f"Test failed unexpectedly with an exception: {e}")
 
     @patch.dict(environ, {OTEL_PROPAGATORS: "a,  b,   c  "})
     @patch("opentelemetry.propagators.composite.CompositePropagator")