add intermediate buffer to meta file download

Author: Mladen Rusev

coverage_server.go

@@ -11,8 +11,6 @@ func startCoverageServer() {
 	adminMux := http.NewServeMux()
 
 	adminMux.HandleFunc("/_debug/coverage/download", func(w http.ResponseWriter, r *http.Request) {
-		log.Println("{\n  \"message\": \"Received request to download coverage counter data...\"\n}")
-
 		var buffer bytes.Buffer
 
 		// Attempt to write the coverage counters to the buffer.
@@ -42,11 +40,25 @@ func startCoverageServer() {
 
 	adminMux.HandleFunc("/_debug/coverage/meta/download", func(w http.ResponseWriter, r *http.Request) {
 		log.Println("Received request to download coverage metadata...")
+
+		var buffer bytes.Buffer
+		if err := coverage.WriteMeta(&buffer); err != nil {
+			log.Printf("Error writing coverage meta to buffer: %v", err)
+			// Inform the client that an internal error occurred.
+			http.Error(w, "Failed to generate coverage meta", http.StatusInternalServerError)
+			return
+		}
+		// Check if any data was written to the buffer.
+		if buffer.Len() == 0 {
+			log.Println("Coverage meta is empty.")
+		} else {
+			log.Printf("Successfully wrote %d bytes of coverage meta to the buffer.", buffer.Len())
+		}
+
 		w.Header().Set("Content-Type", "application/octet-stream")
 		w.Header().Set("Content-Disposition", `attachment; filename="coverage.meta"`)
-
-		if err := coverage.WriteMeta(w); err != nil {
-			log.Printf("Error writing coverage metadata to response: %v", err)
+		if _, err := w.Write(buffer.Bytes()); err != nil {
+			log.Printf("Error writing coverage meta from buffer to response: %v", err)
 		}
 	})