Check data point before yielding (#2745)

Author: ocelotl

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://github.com/open-telemetry/opentelemetry-python/compare/v1.12.0rc1-0.31b0...HEAD)
 
+- Fix yield of `None`-valued points
+  ([#2745](https://github.com/open-telemetry/opentelemetry-python/pull/2745))
 - Add missing `to_json` methods
   ([#2722](https://github.com/open-telemetry/opentelemetry-python/pull/2722)
 - Fix type hints for textmap `Getter` and `Setter`

opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/_view_instrument_match.py

@@ -130,6 +130,8 @@ def collect(
 
         with self._lock:
             for aggregation in self._attributes_aggregation.values():
-                yield aggregation.collect(
+                data_point = aggregation.collect(
                     aggregation_temporality, collection_start_nanos
                 )
+                if data_point is not None:
+                    yield data_point

opentelemetry-sdk/tests/metrics/test_view_instrument_match.py

@@ -212,6 +212,78 @@ def test_collect(self):
         self.assertEqual(number_data_point.attributes, {"c": "d"})
         self.assertEqual(number_data_point.value, 0)
 
+    def test_data_point_check(self):
+        instrument1 = Counter(
+            "instrument1",
+            Mock(),
+            Mock(),
+            description="description",
+            unit="unit",
+        )
+        instrument1.instrumentation_scope = self.mock_instrumentation_scope
+
+        view_instrument_match = _ViewInstrumentMatch(
+            view=View(
+                instrument_name="instrument1",
+                name="name",
+                aggregation=DefaultAggregation(),
+            ),
+            instrument=instrument1,
+            instrument_class_aggregation=MagicMock(
+                **{
+                    "__getitem__.return_value": Mock(
+                        **{
+                            "_create_aggregation.return_value": Mock(
+                                **{
+                                    "collect.side_effect": [
+                                        Mock(),
+                                        Mock(),
+                                        None,
+                                        Mock(),
+                                    ]
+                                }
+                            )
+                        }
+                    )
+                }
+            ),
+        )
+
+        view_instrument_match.consume_measurement(
+            Measurement(
+                value=0,
+                instrument=Mock(name="instrument1"),
+                attributes={"c": "d", "f": "g"},
+            )
+        )
+        view_instrument_match.consume_measurement(
+            Measurement(
+                value=0,
+                instrument=Mock(name="instrument1"),
+                attributes={"h": "i", "j": "k"},
+            )
+        )
+        view_instrument_match.consume_measurement(
+            Measurement(
+                value=0,
+                instrument=Mock(name="instrument1"),
+                attributes={"l": "m", "n": "o"},
+            )
+        )
+        view_instrument_match.consume_measurement(
+            Measurement(
+                value=0,
+                instrument=Mock(name="instrument1"),
+                attributes={"p": "q", "r": "s"},
+            )
+        )
+
+        result = view_instrument_match.collect(
+            AggregationTemporality.CUMULATIVE, 0
+        )
+
+        self.assertEqual(len(list(result)), 3)
+
     def test_setting_aggregation(self):
         instrument1 = Counter(
             name="instrument1",