added multiline support to prefixed writer

Author: roboslone

prefixed_writer.go

@@ -1,6 +1,9 @@
 package framework
 
-import "io"
+import (
+	"bytes"
+	"io"
+)
 
 type PrefixedWriter struct {
 	w      io.Writer
@@ -12,12 +15,13 @@ func NewPrefixedWriter(w io.Writer, prefix string) *PrefixedWriter {
 }
 
 func (w *PrefixedWriter) Write(p []byte) (int, error) {
-	msg := make([]byte, len(p)+len(w.prefix))
-	msg = append(msg, w.prefix...)
-	msg = append(msg, p...)
-
-	if _, err := w.w.Write(msg); err != nil {
-		return 0, err
+	for line := range bytes.SplitSeq(p, []byte("\n")) {
+		msg := make([]byte, len(line)+len(w.prefix))
+		msg = append(msg, w.prefix...)
+		msg = append(msg, line...)
+		if _, err := w.w.Write(msg); err != nil {
+			return 0, err
+		}
 	}
 	return len(p), nil
 }