Show helpful message when propagator is not found (open-telemetry#3259)

srikanthccv · lzchen · ocelotl · web-flow · commit f4aecdf5cee9 · 2023-06-27T10:27:49.000+02:00
Co-authored-by: Leighton Chen &lt;lechen@microsoft.com&gt;
Co-authored-by: Diego Hurtado &lt;ocelotl@users.noreply.github.com&gt;
diff --git a/opentelemetry-api/src/opentelemetry/propagate/__init__.py b/opentelemetry-api/src/opentelemetry/propagate/__init__.py
@@ -144,11 +144,12 @@ def inject(
                 )
             ).load()()
         )
-
-    except Exception:  # pylint: disable=broad-except
-        logger.exception(
-            "Failed to load configured propagator: %s", propagator
+    except StopIteration:
+        raise ValueError(
+            f"Propagator {propagator} not found. It is either misspelled or not installed."
         )
+    except Exception:  # pylint: disable=broad-except
+        logger.exception("Failed to load propagator: %s", propagator)
         raise
 
 
diff --git a/opentelemetry-api/tests/propagators/test_propagators.py b/opentelemetry-api/tests/propagators/test_propagators.py
@@ -15,7 +15,6 @@
 # type: ignore
 
 from importlib import reload
-from logging import ERROR
 from os import environ
 from unittest import TestCase
 from unittest.mock import Mock, patch
@@ -109,16 +108,16 @@ def test_propagators(propagators):
     )
     def test_composite_propagators_error(self):
 
-        # pylint: disable=import-outside-toplevel
-        import opentelemetry.propagate
+        with self.assertRaises(ValueError) as cm:
+            # pylint: disable=import-outside-toplevel
+            import opentelemetry.propagate
+
+            reload(opentelemetry.propagate)
 
-        with self.assertRaises(Exception):
-            with self.assertLogs(level=ERROR) as err:
-                reload(opentelemetry.propagate)
-                self.assertIn(
-                    "Failed to load configured propagator `unknown`",
-                    err.output[0],
-                )
+        self.assertEqual(
+            str(cm.exception),
+            "Propagator unknown not found. It is either misspelled or not installed.",
+        )
 
 
 class TestTraceContextTextMapPropagator(TestCase):

Original file line number	Diff line number	Diff line change
`@@ -144,11 +144,12 @@ def inject(`
`144`	`144`	`)`
`145`	`145`	`).load()()`
`146`	`146`	`)`
`147`		`-`
`148`		`- except Exception: # pylint: disable=broad-except`
`149`		`- logger.exception(`
`150`		`- "Failed to load configured propagator: %s", propagator`
	`147`	`+ except StopIteration:`
	`148`	`+ raise ValueError(`
	`149`	`+ f"Propagator {propagator} not found. It is either misspelled or not installed."`
`151`	`150`	`)`
	`151`	`+ except Exception: # pylint: disable=broad-except`
	`152`	`+ logger.exception("Failed to load propagator: %s", propagator)`
`152`	`153`	`raise`
`153`	`154`
`154`	`155`