Add test

Author: DylanRussell

opentelemetry-sdk/tests/test_configurator.py

@@ -484,6 +484,30 @@ def f():
         assert exporter.credentials is credential_for_traces_only
         assert exporter.credentials is not credential_for_all_signals
 
+    @patch.dict(
+        environ,
+        {
+            OTEL_PYTHON_EXPORTER_OTLP_TRACES_CREDENTIAL_PROVIDER: "custom_credential"
+        },
+    )
+    @patch("opentelemetry.sdk._configuration.entry_points")
+    def test_that_invalid_credential_type_raises_exception(
+        self, mock_entry_points
+    ):
+        def f():
+            # Entry point must return a grpc.ChannelCredential or requests.Session.
+            return 32
+
+        mock_entry_points.configure_mock(
+            return_value=[IterEntryPoint("custom_credential", f)]
+        )
+        with raises(RuntimeError):
+            _init_exporter(
+                "traces",
+                {},
+                OTLPSpanExporter,
+            )
+
     @patch.dict(
         "os.environ", {OTEL_TRACES_SAMPLER: "non_existent_entry_point"}
     )