Adding a simple dataref extension, similar to the java sdk

Signed-off-by: Matthias Wessendorf <[email protected]>

v2/extensions/dataref_extension.go

@@ -0,0 +1,41 @@
+/*
+ Copyright 2024 The CloudEvents Authors
+ SPDX-License-Identifier: Apache-2.0
+*/
+
+package extensions
+
+import (
+	"github.com/cloudevents/sdk-go/v2/event"
+	"github.com/cloudevents/sdk-go/v2/types"
+	"net/url"
+)
+
+const DataRefExtensionKey = "dataref"
+
+type DataRefExtension struct {
+	DataRef *url.URL `json:"dataref"`
+}
+
+func AddDataRefExtension(e *event.Event, dataRef string) error {
+	parsedURL, err := url.Parse(dataRef)
+	if err != nil {
+		return err
+	}
+
+	e.SetExtension(DataRefExtensionKey, parsedURL.String())
+	return nil
+}
+
+func GetDataRefExtension(e event.Event) (DataRefExtension, bool) {
+	if dataRefValue, ok := e.Extensions()[DataRefExtensionKey]; ok {
+		if dataRefStr, err := types.ToString(dataRefValue); err == nil {
+			parsedURL, err := url.Parse(dataRefStr)
+			if err != nil {
+				return DataRefExtension{}, false
+			}
+			return DataRefExtension{DataRef: parsedURL}, true
+		}
+	}
+	return DataRefExtension{}, false
+}

v2/extensions/dataref_extension_test.go

@@ -0,0 +1,77 @@
+/*
+ Copyright 2024 The CloudEvents Authors
+ SPDX-License-Identifier: Apache-2.0
+*/
+
+package extensions
+
+import (
+	"net/url"
+	"testing"
+
+	"github.com/cloudevents/sdk-go/v2/event"
+)
+
+func TestAddDataRefExtensionValidURL(t *testing.T) {
+	e := event.New()
+	expectedDataRef := "https://example.com/data"
+
+	err := AddDataRefExtension(&e, expectedDataRef)
+	if err != nil {
+		t.Fatalf("Failed to add DataRefExtension with valid URL: %s", err)
+	}
+}
+
+func TestAddDataRefExtensionInvalidURL(t *testing.T) {
+	e := event.New()
+	invalidDataRef := "://invalid-url"
+
+	err := AddDataRefExtension(&e, invalidDataRef)
+	if err == nil {
+		t.Fatal("Expected error when adding DataRefExtension with invalid URL, but got none")
+	}
+}
+
+func TestGetDataRefExtensionNotFound(t *testing.T) {
+	e := event.New()
+
+	_, ok := GetDataRefExtension(e)
+	if ok {
+		t.Fatal("Expected not to find DataRefExtension, but did")
+	}
+}
+
+func TestSerializationAndDeserialization(t *testing.T) {
+	e := event.New()
+	dataRef := "https://example.com/data"
+
+	err := AddDataRefExtension(&e, dataRef)
+	if err != nil {
+		t.Fatalf("Failed to add DataRefExtension: %s", err)
+	}
+
+	bytes, err := e.MarshalJSON()
+	if err != nil {
+		t.Fatalf("Failed to marshal event with DataRefExtension: %s", err)
+	}
+
+	var deserializedEvent event.Event
+	err = deserializedEvent.UnmarshalJSON(bytes)
+	if err != nil {
+		t.Fatalf("Failed to unmarshal event with DataRefExtension: %s", err)
+	}
+
+	dataRefExtension, ok := GetDataRefExtension(deserializedEvent)
+	if !ok {
+		t.Fatal("Expected to find DataRefExtension after deserialization, but did not")
+	}
+
+	expectedURL, err := url.Parse(dataRef)
+	if err != nil {
+		t.Fatalf("Failed to parse expected DataRef URL: %s", err)
+	}
+
+	if dataRefExtension.DataRef.String() != expectedURL.String() {
+		t.Errorf("Expected DataRefExtension.DataRef to be '%s', but got '%s' after deserialization", expectedURL, dataRefExtension.DataRef)
+	}
+}