Review updates

* Expanded test for NewEventsFromHTTPRequest
* Implemented NewHTTPRequestFromEvent as well

v2/protocol/http/utility.go

@@ -39,7 +39,25 @@ func NewEventsFromHTTPResponse(resp *nethttp.Response) ([]event.Event, error) {
 	return binding.ToEvents(context.Background(), msg, msg.BodyReader)
 }
 
-// NewHTTPRequestFromEvents creates a http.Request object that can be used with any http.Client.
+// NewHTTPRequestFromEvent creates a http.Request object that can be used with any http.Client for a singular event.
+func NewHTTPRequestFromEvent(ctx context.Context, url string, event event.Event) (*nethttp.Request, error) {
+	if err := event.Validate(); err != nil {
+		return nil, err
+	}
+
+	req, err := nethttp.NewRequestWithContext(ctx, nethttp.MethodPost, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	if err := WriteRequest(ctx, (*binding.EventMessage)(&event), req); err != nil {
+		return nil, err
+	}
+
+	return req, nil
+}
+
+// NewHTTPRequestFromEvents creates a http.Request object that can be used with any http.Client for sending
+// a batched set of events.
 func NewHTTPRequestFromEvents(ctx context.Context, url string, events []event.Event) (*nethttp.Request, error) {
 	// Sending batch events is quite straightforward, as there is only JSON format, so a simple implementation.
 	for _, e := range events {

v2/protocol/http/utility_test.go

@@ -12,6 +12,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 
 	"github.com/cloudevents/sdk-go/v2/binding"
@@ -92,13 +93,58 @@ func TestNewEventFromHttpResponse(t *testing.T) {
 }
 
 func TestNewEventsFromHTTPRequest(t *testing.T) {
-	req := httptest.NewRequest("POST", "http://localhost", bytes.NewReader([]byte(`[{"data":"foo","datacontenttype":"application/json","id":"id","source":"source","specversion":"1.0","type":"type"}]`)))
-	req.Header.Set(ContentType, event.ApplicationCloudEventsBatchJSON)
+	type expected struct {
+		len int
+		ids []string
+	}
 
-	events, err := NewEventsFromHTTPRequest(req)
-	require.NoError(t, err)
-	require.Len(t, events, 1)
-	test.AssertEvent(t, events[0], test.IsValid())
+	fixtures := map[string]struct {
+		jsn      string
+		expected expected
+	}{
+		"single": {
+			jsn: `[{"data":"foo","datacontenttype":"application/json","id":"id","source":"source","specversion":"1.0","type":"type"}]`,
+			expected: expected{
+				len: 1,
+				ids: []string{"id"},
+			},
+		},
+		"triple": {
+			jsn: `[{"data":"foo","datacontenttype":"application/json","id":"id1","source":"source","specversion":"1.0","type":"type"},{"data":"foo","datacontenttype":"application/json","id":"id2","source":"source","specversion":"1.0","type":"type"},{"data":"foo","datacontenttype":"application/json","id":"id3","source":"source","specversion":"1.0","type":"type"}]`,
+			expected: expected{
+				len: 3,
+				ids: []string{"id1", "id2", "id3"},
+			},
+		},
+	}
+
+	for k, v := range fixtures {
+		t.Run(k, func(t *testing.T) {
+			req := httptest.NewRequest("POST", "http://localhost", bytes.NewReader([]byte(v.jsn)))
+			req.Header.Set(ContentType, event.ApplicationCloudEventsBatchJSON)
+
+			events, err := NewEventsFromHTTPRequest(req)
+			require.NoError(t, err)
+			require.Len(t, events, v.expected.len)
+			for i, e := range events {
+				test.AssertEvent(t, e, test.IsValid())
+				require.Equal(t, v.expected.ids[i], events[i].ID())
+			}
+		})
+	}
+
+	t.Run("bad request", func(t *testing.T) {
+		e := event.New()
+		e.SetID(uuid.New().String())
+		e.SetSource("example/uri")
+		e.SetType("example.type")
+		require.NoError(t, e.SetData(event.ApplicationJSON, map[string]string{"hello": "world"}))
+		req, err := NewHTTPRequestFromEvent(context.Background(), "http://localhost", e)
+		require.NoError(t, err)
+
+		_, err = NewEventsFromHTTPRequest(req)
+		require.ErrorContainsf(t, err, "cannot convert message to batched events", "error should include message")
+	})
 }
 
 func TestNewEventsFromHTTPResponse(t *testing.T) {
@@ -116,6 +162,42 @@ func TestNewEventsFromHTTPResponse(t *testing.T) {
 	test.AssertEvent(t, events[0], test.IsValid())
 }
 
+func TestNewHTTPRequestFromEvent(t *testing.T) {
+	e := event.New()
+	e.SetID(uuid.New().String())
+	e.SetSource("example/uri")
+	e.SetType("example.type")
+	require.NoError(t, e.SetData(event.ApplicationJSON, map[string]string{"hello": "world"}))
+
+	// echo back what we get, so we can compare events at either side.
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set(ContentType, r.Header.Get(ContentType))
+		// copy across structured headers
+		for k, v := range r.Header {
+			if strings.HasPrefix(k, "Ce-") {
+				w.Header()[k] = v
+			}
+		}
+
+		b, err := io.ReadAll(r.Body)
+		require.NoError(t, err)
+		require.NoError(t, r.Body.Close())
+		_, err = w.Write(b)
+		require.NoError(t, err)
+	}))
+	defer ts.Close()
+
+	req, err := NewHTTPRequestFromEvent(context.Background(), ts.URL, e)
+	require.NoError(t, err)
+
+	resp, err := ts.Client().Do(req)
+	require.NoError(t, err)
+
+	result, err := NewEventFromHTTPResponse(resp)
+	require.NoError(t, err)
+	require.Equal(t, &e, result)
+}
+
 func TestNewHTTPRequestFromEvents(t *testing.T) {
 	var events []event.Event
 	e := event.New()
@@ -151,6 +233,5 @@ func TestNewHTTPRequestFromEvents(t *testing.T) {
 
 	result, err := NewEventsFromHTTPResponse(resp)
 	require.NoError(t, err)
-
 	require.Equal(t, events, result)
 }