otelhttp: export Event type for WithMessageEvents

CHANGELOG.md

@@ -26,6 +26,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 ### Changed
 
 - Improve performance by reducing allocations in the gRPC stats handler in `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc`. (#8035)
+- Export the `ReadEvents` and `WriteEvents` constants in `go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp` so they can be used in `WithMessageEvents`. (#8153)
 
 ### Deprecated
 

instrumentation/net/http/otelhttp/config.go

@@ -144,11 +144,13 @@ func WithFilter(f Filter) Option {
 	})
 }
 
-type event int
+// Event represents message event types for [WithMessageEvents].
+type Event int
 
 // Different types of events that can be recorded, see WithMessageEvents.
 const (
-	ReadEvents event = iota
+	unspecifiedEvents Event = iota
+	ReadEvents
 	WriteEvents
 )
 
@@ -161,7 +163,7 @@ const (
 //     using the ReadBytesKey
 //   - WriteEvents: Record the number of bytes written after every http.ResponeWriter.Write
 //     using the WriteBytesKey
-func WithMessageEvents(events ...event) Option {
+func WithMessageEvents(events ...Event) Option {
 	return optionFunc(func(c *config) {
 		for _, e := range events {
 			switch e {

instrumentation/net/http/otelhttp/config_test.go

@@ -122,3 +122,48 @@ func TestSpanNameFormatter(t *testing.T) {
 		})
 	}
 }
+
+func TestEvent(t *testing.T) {
+	t.Run("constant values", func(t *testing.T) {
+		assert.Equal(t, otelhttp.ReadEvents, otelhttp.Event(1), "ReadEvents should be 1")
+		assert.Equal(t, otelhttp.WriteEvents, otelhttp.Event(2), "WriteEvents should be 2")
+	})
+
+	t.Run("unspecifiedEvent", func(t *testing.T) {
+		var unspecified otelhttp.Event // zero-value
+		assert.Equal(t, otelhttp.Event(0), unspecified, "unspecifiedEvent should be zero-value Event")
+
+		// Validate that unspecifiedEvent is different from defined events
+		assert.NotEqual(t, otelhttp.ReadEvents, unspecified, "unspecifiedEvent should not equal ReadEvents")
+		assert.NotEqual(t, otelhttp.WriteEvents, unspecified, "unspecifiedEvent should not equal WriteEvents")
+
+		// Validate WithMessageEvents accepts unspecifiedEvent
+		opt := otelhttp.WithMessageEvents(unspecified)
+		assert.NotNil(t, opt, "WithMessageEvents(unspecifiedEvent) should not return nil")
+
+		// Additional validation: test behavior with unspecified events
+		optMultiple := otelhttp.WithMessageEvents(unspecified, otelhttp.ReadEvents)
+		assert.NotNil(t, optMultiple, "WithMessageEvents with unspecified and valid events should not return nil")
+	})
+
+	t.Run("WithMessageEvents", func(t *testing.T) {
+		tests := []struct {
+			name   string
+			events []otelhttp.Event
+		}{
+			{name: "ReadEvents", events: []otelhttp.Event{otelhttp.ReadEvents}},
+			{name: "WriteEvents", events: []otelhttp.Event{otelhttp.WriteEvents}},
+			{name: "multiple events", events: []otelhttp.Event{otelhttp.ReadEvents, otelhttp.WriteEvents}},
+			{name: "no events", events: []otelhttp.Event{}},
+			{name: "unspecified event only", events: []otelhttp.Event{otelhttp.Event(0)}},
+			{name: "mixed with unspecified", events: []otelhttp.Event{otelhttp.Event(0), otelhttp.ReadEvents}},
+		}
+
+		for _, tt := range tests {
+			t.Run(tt.name, func(t *testing.T) {
+				got := otelhttp.WithMessageEvents(tt.events...)
+				assert.NotNil(t, got, "WithMessageEvents(%v) should not return nil", tt.events)
+			})
+		}
+	})
+}