Add test to verify functionality and fix things

receiver/datadogreceiver/receiver.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"strings"
 
 	"github.com/DataDog/agent-payload/v5/gogen"
 	pb "github.com/DataDog/datadog-agent/pkg/proto/pbgo/trace"
@@ -243,8 +244,9 @@ func (ddr *datadogReceiver) handleTraces(w http.ResponseWriter, req *http.Reques
 		}
 	}
 
-	switch version := req.Header.Get(header.TracerVersion); version {
-	case "0.1", "0.2", "0.3":
+	urlSplit := strings.Split(req.RequestURI, "/")
+	switch version := urlSplit[1]; version {
+	case "v0.1", "v0.2", "v0.3":
 		_, _ = w.Write([]byte("OK"))
 	default:
 		_, _ = w.Write([]byte("{}"))

receiver/datadogreceiver/receiver_test.go

@@ -74,32 +74,49 @@ func TestDatadogServer(t *testing.T) {
 	})
 
 	for _, tc := range []struct {
-		name string
-		op   io.Reader
+		name     string
+		op       io.Reader
+		endpoint string
 
 		expectCode    int
 		expectContent string
 	}{
 		{
 			name:          "invalid data",
 			op:            strings.NewReader("{"),
+			endpoint:      "http://%s/v0.7/traces",
 			expectCode:    http.StatusBadRequest,
 			expectContent: "Unable to unmarshal reqs\n",
 		},
 		{
 			name:          "Fake featuresdiscovery",
 			op:            nil, // Content-length: 0.
+			endpoint:      "http://%s/v0.7/traces",
 			expectCode:    http.StatusBadRequest,
 			expectContent: "Fake featuresdiscovery\n",
 		},
+		{
+			name:          "Older version returns OK",
+			op:            strings.NewReader("[]"),
+			endpoint:      "http://%s/v0.3/traces",
+			expectCode:    http.StatusOK,
+			expectContent: "OK",
+		},
+		{
+			name:          "Older version returns JSON",
+			op:            strings.NewReader("[]"),
+			endpoint:      "http://%s/v0.4/traces",
+			expectCode:    http.StatusOK,
+			expectContent: "{}",
+		},
 	} {
 		tc := tc
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
 
 			req, err := http.NewRequest(
 				http.MethodPost,
-				fmt.Sprintf("http://%s/v0.7/traces", dd.(*datadogReceiver).address),
+				fmt.Sprintf(tc.endpoint, dd.(*datadogReceiver).address),
 				tc.op,
 			)
 			require.NoError(t, err, "Must not error when creating request")