Make subscription tests more robust. Fix some issues

subscription.go

@@ -89,7 +89,7 @@ func (s *HTTPSubscriber) downloadAndAppend() {
 	case (resp.StatusCode >= http.StatusBadRequest &&
 		resp.StatusCode != http.StatusRequestedRangeNotSatisfiable) ||
 		resp.StatusCode >= http.StatusInternalServerError:
-		logger.Errorf("%s: server returned with unexpected code %s", resp.StatusCode)
+		logger.Errorf("%s: server returned with unexpected code %d", s.LocalFile, resp.StatusCode)
 		// error is ignored, we continued subscribed
 	}
 }

subscription_test.go

@@ -13,10 +13,49 @@ func createTestServer() *httptest.Server {
 	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		// Simulate serving a file from the server
 		data := []byte("This is the remote content.")
-		w.Header().Set("Content-Range", fmt.Sprintf("bytes 0-%d/%d", len(data)-1, len(data)))
-		w.Header().Set("Content-Length", fmt.Sprint(len(data)))
-		w.WriteHeader(http.StatusPartialContent)
-		_, _ = w.Write(data)
+		contentLength := len(data)
+
+		// Get the "Range" header from the request
+		rangeHeader := r.Header.Get("Range")
+
+		if rangeHeader != "" {
+			var start, end int
+
+			// Check for a range request in the format "bytes %d-"
+			if n, _ := fmt.Sscanf(rangeHeader, "bytes=%d-", &start); n == 1 {
+				// Handle open end range requests
+				if start >= contentLength {
+					http.Error(w, "Invalid Range header", http.StatusRequestedRangeNotSatisfiable)
+					return
+				}
+				end = contentLength - 1
+			} else if n, _ := fmt.Sscanf(rangeHeader, "bytes=%d-%d", &start, &end); n == 2 {
+				// Check for valid byte range
+				if start < 0 || end >= contentLength || start > end {
+					http.Error(w, "Invalid Range header", http.StatusRequestedRangeNotSatisfiable)
+					return
+				}
+			} else {
+				http.Error(w, "Invalid Range header", http.StatusBadRequest)
+				return
+			}
+
+			// Calculate the content range and length for the response
+			contentRange := fmt.Sprintf("bytes %d-%d/%d", start, end, contentLength)
+			w.Header().Set("Content-Range", contentRange)
+			w.Header().Set("Content-Length", fmt.Sprint(end-start+1))
+			w.WriteHeader(http.StatusPartialContent)
+
+			// Write the selected byte range to the response
+			_, _ = w.Write(data[start : end+1])
+		} else {
+			// If no "Range" header, serve the entire content
+			w.Header().Set("Content-Range", fmt.Sprintf("bytes 0-%d/%d", contentLength-1, contentLength))
+			w.Header().Set("Content-Length", fmt.Sprint(contentLength))
+			w.WriteHeader(http.StatusPartialContent)
+
+			_, _ = w.Write(data)
+		}
 	}))
 }
 
@@ -31,7 +70,7 @@ func TestHTTPSubscriber(t *testing.T) {
 	go subscriber.Subscribe()
 
 	// Allow some time for subscription to run
-	time.Sleep(time.Second)
+	time.Sleep(2 * time.Second)
 	subscriber.Stop()
 
 	localFileContent, err := os.ReadFile(localFile)