Add TestCollectExemplars

sdk/metric/internal/aggregate/exemplar.go

@@ -32,13 +32,11 @@ func collectExemplars[N int64 | float64](out *[]metricdata.Exemplar[N], f func(*
 		(*out)[i].SpanID = e.SpanID
 		(*out)[i].TraceID = e.TraceID
 
-		val := (*out)[i].Value
-		valPtr := any(&val)
-		switch v := valPtr.(type) {
-		case *int64:
-			*v = e.Value.Int64()
-		case *float64:
-			*v = e.Value.Float64()
+		switch e.Value.Type() {
+		case exemplar.Int64ValueType:
+			(*out)[i].Value = N(e.Value.Int64())
+		case exemplar.Float64ValueType:
+			(*out)[i].Value = N(e.Value.Float64())
 		}
 	}
 }

sdk/metric/internal/aggregate/exemplar_test.go

@@ -0,0 +1,49 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package aggregate
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/sdk/metric/internal/exemplar"
+	"go.opentelemetry.io/otel/sdk/metric/metricdata"
+)
+
+func TestCollectExemplars(t *testing.T) {
+	t.Run("Int64", testCollectExemplars[int64]())
+	t.Run("Float64", testCollectExemplars[float64]())
+}
+
+func testCollectExemplars[N int64 | float64]() func(t *testing.T) {
+	return func(t *testing.T) {
+		now := time.Now()
+		alice := attribute.String("user", "Alice")
+		value := N(1)
+		spanID := [8]byte{0x1}
+		traceID := [16]byte{0x1}
+
+		out := new([]metricdata.Exemplar[N])
+		collectExemplars(out, func(in *[]exemplar.Exemplar) {
+			*in = reset(*in, 1, 1)
+			(*in)[0] = exemplar.Exemplar{
+				FilteredAttributes: []attribute.KeyValue{alice},
+				Time:               now,
+				Value:              exemplar.NewValue(value),
+				SpanID:             spanID[:],
+				TraceID:            traceID[:],
+			}
+		})
+
+		assert.Equal(t, []metricdata.Exemplar[N]{{
+			FilteredAttributes: []attribute.KeyValue{alice},
+			Time:               now,
+			Value:              value,
+			SpanID:             spanID[:],
+			TraceID:            traceID[:],
+		}}, *out)
+	}
+}