[processor/deltatocumulative]: do not drop Gauge, Summary (#35372)

**Description:**
As an oversight,
#33286
not only started dropping metrics without datapoints, but also all
Gauges and Summaries.
This change correctly passes those types through unaltered.

**Link to tracking Issue:** Fixes #35284 

**Testing:** `TestIgnore` was added _before_ fixing. It fails on current
main, passes after this change

**Documentation:** not needed

---------

Co-authored-by: Juraci Paixão Kröhling <[email protected]>

.chloggen/deltatocumulative-fix-drops.yaml

@@ -0,0 +1,29 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: deltatocumulative
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: do not drop gauges and summaries
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [35284]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  Gauges and Summaries are no longer dropped from processor output.
+  Instead, they are passed through as-is
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

processor/deltatocumulativeprocessor/go.mod

@@ -5,6 +5,7 @@ go 1.22.0
 require (
 	github.com/google/go-cmp v0.6.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/internal/exp/metrics v0.109.0
+	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/golden v0.109.0
 	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/pdatatest v0.109.0
 	github.com/stretchr/testify v1.9.0
 	go.opentelemetry.io/collector/component v0.110.0

processor/deltatocumulativeprocessor/processor.go

@@ -138,7 +138,10 @@ func (p *Processor) ConsumeMetrics(ctx context.Context, md pmetric.Metrics) erro
 	var errs error
 	metrics.Filter(md, func(m metrics.Metric) bool {
 		var n int
+		//exhaustive:enforce
 		switch m.Type() {
+		case pmetric.MetricTypeGauge:
+			n = m.Gauge().DataPoints().Len()
 		case pmetric.MetricTypeSum:
 			sum := m.Sum()
 			if sum.AggregationTemporality() == pmetric.AggregationTemporalityDelta {
@@ -163,6 +166,8 @@ func (p *Processor) ConsumeMetrics(ctx context.Context, md pmetric.Metrics) erro
 				expo.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
 			}
 			n = expo.DataPoints().Len()
+		case pmetric.MetricTypeSummary:
+			n = m.Summary().DataPoints().Len()
 		}
 		return n > 0
 	})

processor/deltatocumulativeprocessor/processor_test.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"math"
 	"math/rand"
+	"path/filepath"
 	"strconv"
 	"testing"
 	"time"
@@ -20,6 +21,7 @@ import (
 	"go.opentelemetry.io/collector/processor/processortest"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/internal/exp/metrics/identity"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/golden"
 	self "github.com/open-telemetry/opentelemetry-collector-contrib/processor/deltatocumulativeprocessor"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/deltatocumulativeprocessor/internal/data"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/deltatocumulativeprocessor/internal/data/datatest/compare"
@@ -282,3 +284,27 @@ func stream() SumBuilder {
 	_, base := sum.Stream()
 	return SumBuilder{Metric: sum, base: base}
 }
+
+func TestIgnore(t *testing.T) {
+	proc, sink := setup(t, nil)
+
+	dir := "./testdata/notemporality-ignored"
+	open := func(file string) pmetric.Metrics {
+		t.Helper()
+		md, err := golden.ReadMetrics(filepath.Join(dir, file))
+		require.NoError(t, err)
+		return md
+	}
+
+	in := open("in.yaml")
+	out := open("out.yaml")
+
+	ctx := context.Background()
+
+	err := proc.ConsumeMetrics(ctx, in)
+	require.NoError(t, err)
+
+	if diff := compare.Diff([]pmetric.Metrics{out}, sink.AllMetrics()); diff != "" {
+		t.Fatal(diff)
+	}
+}

processor/deltatocumulativeprocessor/testdata/notemporality-ignored/in.yaml

@@ -0,0 +1,27 @@
+resourceMetrics:
+  - schemaUrl: https://test.com/resource
+    resource:
+      attributes:
+        - key: resattr
+          value: { stringValue: stringoo }
+    scopeMetrics:
+      - schemaUrl: https://test.com/scope
+        scope:
+          name: Test
+          version: 1.2.3
+          attributes:
+            - key: scopeattr
+              value: { stringValue: string }
+        metrics:
+          - name: test.gauge
+            gauge:
+              dataPoints:
+                - timeUnixNano: 1
+                  asDouble: 1
+          - name: test.summary
+            summary:
+              dataPoints:
+                - timeUnixNano: 1
+                  quantileValues:
+                    - quantile: 0.25
+                      value: 25

processor/deltatocumulativeprocessor/testdata/notemporality-ignored/out.yaml

@@ -0,0 +1,27 @@
+resourceMetrics:
+  - schemaUrl: https://test.com/resource
+    resource:
+      attributes:
+        - key: resattr
+          value: { stringValue: stringoo }
+    scopeMetrics:
+      - schemaUrl: https://test.com/scope
+        scope:
+          name: Test
+          version: 1.2.3
+          attributes:
+            - key: scopeattr
+              value: { stringValue: string }
+        metrics:
+          - name: test.gauge
+            gauge:
+              dataPoints:
+                - timeUnixNano: 1
+                  asDouble: 1
+          - name: test.summary
+            summary:
+              dataPoints:
+                - timeUnixNano: 1
+                  quantileValues:
+                    - quantile: 0.25
+                      value: 25