add intermediate buffer

Author: Mladen Rusev

coverage_server.go

@@ -1,22 +1,42 @@
 package main
 
 import (
+	"bytes"
 	"log"
 	"net/http"
 	"runtime/coverage"
 )
 
 func startCoverageServer() {
-	//log.Println("Coverage build detected. Starting private admin server on localhost:8081...")
 	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.
+		if err := coverage.WriteCounters(&buffer); err != nil {
+			log.Printf("Error writing coverage counters to buffer: %v", err)
+			// Inform the client that an internal error occurred.
+			http.Error(w, "Failed to generate coverage report", http.StatusInternalServerError)
+			return
+		}
+
+		// Check if any data was written to the buffer.
+		if buffer.Len() == 0 {
+			log.Println("Coverage data is empty. No counters were written.")
+		} else {
+			log.Printf("Successfully wrote %d bytes of coverage data to the buffer.", buffer.Len())
+		}
+
+		// If successful, proceed to write the buffer's content to the actual HTTP response.
 		w.Header().Set("Content-Type", "application/octet-stream")
 		w.Header().Set("Content-Disposition", `attachment; filename="coverage.out"`)
 
-		if err := coverage.WriteCounters(w); err != nil {
-			log.Printf("Error writing coverage counters to response: %v", err)
+		// Write the captured coverage data from the buffer to the response writer.
+		if _, err := w.Write(buffer.Bytes()); err != nil {
+			log.Printf("Error writing coverage data from buffer to response: %v", err)
 		}
 	})