test(opentelemetry): add missing package tests

go.mod

@@ -14,6 +14,8 @@ require (
 	github.com/testcontainers/testcontainers-go/modules/postgres v0.42.0
 	go.opentelemetry.io/otel v1.43.0
 	go.opentelemetry.io/otel/metric v1.43.0
+	go.opentelemetry.io/otel/sdk v1.43.0
+	go.opentelemetry.io/otel/sdk/metric v1.43.0
 	go.opentelemetry.io/otel/trace v1.43.0
 	google.golang.org/genproto v0.0.0-20260420184626-e10c466a9529
 	google.golang.org/protobuf v1.36.11

go.sum

@@ -250,6 +250,8 @@ go.uber.org/atomic v1.3.2/go.mod h1:gD2HeocX3+yG+ygLZcrzQJaqmWj9AIm7n08wl/qW/PE=
 go.uber.org/atomic v1.4.0/go.mod h1:gD2HeocX3+yG+ygLZcrzQJaqmWj9AIm7n08wl/qW/PE=
 go.uber.org/atomic v1.5.0/go.mod h1:sABNBOSYdrvTF6hTgEIbc7YasKWGhgEQZyfxyTvoXHQ=
 go.uber.org/atomic v1.6.0/go.mod h1:sABNBOSYdrvTF6hTgEIbc7YasKWGhgEQZyfxyTvoXHQ=
+go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
+go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 go.uber.org/multierr v1.1.0/go.mod h1:wR5kodmAFQ0UK8QlbwjlSNy0Z68gJhDJUG5sjR94q/0=
 go.uber.org/multierr v1.3.0/go.mod h1:VgVr7evmIr6uPjLBxg28wmKNXyqE9akIJ5XnfpiKl+4=
 go.uber.org/multierr v1.5.0/go.mod h1:FeouvMocqHpRaaGuG9EjoKcStLC43Zu/fmqdUMPcKYU=

opentelemetry/config.go

@@ -6,19 +6,27 @@ import (
 	"go.opentelemetry.io/otel/trace"
 )
 
-const instrumentationName = "github.com/get-eventually/go-eventually/opentelemetry"
+// InstrumentationName is the instrumentation scope name used by the Tracer
+// and Meter exposed by this package.
+const InstrumentationName = "github.com/get-eventually/go-eventually/opentelemetry"
+
+// MetricUnitMilliseconds is the [OpenTelemetry-compatible unit] used by the
+// duration histograms exposed by this package.
+//
+// [OpenTelemetry-compatible unit]: https://ucum.org/ucum
+const MetricUnitMilliseconds = "ms"
 
 type config struct {
 	MeterProvider  metric.MeterProvider
 	TracerProvider trace.TracerProvider
 }
 
 func (c config) meter() metric.Meter {
-	return c.MeterProvider.Meter(instrumentationName)
+	return c.MeterProvider.Meter(InstrumentationName)
 }
 
 func (c config) tracer() trace.Tracer {
-	return c.TracerProvider.Tracer(instrumentationName)
+	return c.TracerProvider.Tracer(InstrumentationName)
 }
 
 // Option specifies instrumentation configuration options.

opentelemetry/config_test.go

@@ -0,0 +1,48 @@
+package opentelemetry_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/get-eventually/go-eventually/event"
+	otelex "github.com/get-eventually/go-eventually/opentelemetry"
+	"github.com/get-eventually/go-eventually/version"
+)
+
+func TestWithTracerProvider_OverridesDefault(t *testing.T) {
+	h := newHarness(t)
+
+	ies, err := otelex.NewInstrumentedEventStore(
+		event.NewInMemoryStore(),
+		otelex.WithTracerProvider(h.tracer),
+		otelex.WithMeterProvider(h.meter),
+	)
+	require.NoError(t, err)
+
+	_, err = ies.Append(t.Context(), "stream", version.Any)
+	require.NoError(t, err)
+
+	spans := h.endedSpans()
+	require.Len(t, spans, 1, "expected a span to be recorded by the supplied tracer provider")
+	assert.Equal(t, otelex.InstrumentationName, spans[0].InstrumentationScope().Name)
+}
+
+func TestWithMeterProvider_OverridesDefault(t *testing.T) {
+	h := newHarness(t)
+
+	ies, err := otelex.NewInstrumentedEventStore(
+		event.NewInMemoryStore(),
+		otelex.WithTracerProvider(h.tracer),
+		otelex.WithMeterProvider(h.meter),
+	)
+	require.NoError(t, err)
+
+	_, err = ies.Append(t.Context(), "stream", version.Any)
+	require.NoError(t, err)
+
+	sm := h.collectScopeMetrics(t)
+	assert.Equal(t, otelex.InstrumentationName, sm.Scope.Name)
+	assert.NotEmpty(t, sm.Metrics, "expected metrics on the supplied meter provider")
+}

opentelemetry/event_store.go

@@ -22,6 +22,21 @@ const (
 	EventStoreNumEventsKey        attribute.Key = "event_store.num_events"
 )
 
+// Span names emitted by the InstrumentedEventStore instrumentation.
+const (
+	EventStoreStreamSpanName = "event.Store.Stream"
+	EventStoreAppendSpanName = "event.Store.Append"
+)
+
+// Metric names and descriptions exposed by the InstrumentedEventStore instrumentation.
+const (
+	EventStoreStreamDurationMetricName        = "eventually.event_store.stream.duration.milliseconds"
+	EventStoreStreamDurationMetricDescription = "Duration in milliseconds of event.Store.Stream operations performed."
+
+	EventStoreAppendDurationMetricName        = "eventually.event_store.append.duration.milliseconds"
+	EventStoreAppendDurationMetricDescription = "Duration in milliseconds of event.Store.Append operations performed."
+)
+
 var _ event.Store = new(InstrumentedEventStore)
 
 // InstrumentedEventStore is a wrapper type over an event.Store
@@ -41,17 +56,17 @@ func (ies *InstrumentedEventStore) registerMetrics(meter metric.Meter) error {
 	var err error
 
 	if ies.streamDuration, err = meter.Int64Histogram(
-		"eventually.event_store.stream.duration.milliseconds",
-		metric.WithUnit("ms"),
-		metric.WithDescription("Duration in milliseconds of event.Store.Stream operations performed."),
+		EventStoreStreamDurationMetricName,
+		metric.WithUnit(MetricUnitMilliseconds),
+		metric.WithDescription(EventStoreStreamDurationMetricDescription),
 	); err != nil {
 		return fmt.Errorf("opentelemetry.InstrumentedEventStore: failed to register metric, %w", err)
 	}
 
 	if ies.appendDuration, err = meter.Int64Histogram(
-		"eventually.event_store.append.duration.milliseconds",
-		metric.WithUnit("ms"),
-		metric.WithDescription("Duration in milliseconds of event.Store.Append operations performed."),
+		EventStoreAppendDurationMetricName,
+		metric.WithUnit(MetricUnitMilliseconds),
+		metric.WithDescription(EventStoreAppendDurationMetricDescription),
 	); err != nil {
 		return fmt.Errorf("opentelemetry.InstrumentedEventStore: failed to register metric, %w", err)
 	}
@@ -96,7 +111,7 @@ func (ies *InstrumentedEventStore) Stream(
 	}
 
 	return event.NewStream(func(yield func(event.Persisted) bool) error {
-		ctx, span := ies.tracer.Start(ctx, "event.Store.Stream", trace.WithAttributes(attributes...))
+		ctx, span := ies.tracer.Start(ctx, EventStoreStreamSpanName, trace.WithAttributes(attributes...))
 		start := time.Now()
 
 		inner := ies.eventStore.Stream(ctx, id, selector)
@@ -146,7 +161,7 @@ func (ies *InstrumentedEventStore) Append(
 		EventStoreNumEventsKey.Int(len(events)),
 	}
 
-	ctx, span := ies.tracer.Start(ctx, "event.Store.Append", trace.WithAttributes(attributes...))
+	ctx, span := ies.tracer.Start(ctx, EventStoreAppendSpanName, trace.WithAttributes(attributes...))
 	start := time.Now()
 
 	defer func() {