1 files changed, 51 insertions, 0 deletions

diff --git a/xdelta3/go/src/xdelta/tgroup.go b/xdelta3/go/src/xdelta/tgroup.go
index c7337c6..1852bac 100644
--- a/xdelta3/go/src/xdelta/tgroup.go
+++ b/xdelta3/go/src/xdelta/tgroup.go
@@ -2,6 +2,7 @@ package xdelta
 
 import (
         "fmt"
+        "io"
         "sync"
         "time"
 )
@@ -109,3 +110,53 @@ func waitAll(t *TestGroup, wc chan bool) {
         }
         wc <- true
 }
+
+type dualWriter struct {
+        e, d chan []byte
+}
+
+func (d *dualWriter) Write(p []byte) (int, error) {
+        if len(p) != 0 {
+                d.e <- p
+                d.d <- p
+        }
+        return len(p), nil
+}
+
+func (d *dualWriter) Close() error {
+        d.e <- nil
+        d.d <- nil
+        _ = <- d.e
+        _ = <- d.d
+        return nil
+}
+
+func newWriter(c chan []byte, a io.WriteCloser) func (Goroutine) {
+        return func (g Goroutine) {
+                for {
+                        d := <- c
+                        if d == nil {
+                                if err := a.Close(); err != nil {
+                                        g.Panic(err)
+                                }
+                                c <- nil
+                                g.OK()
+                                return
+                        }
+                        if num, err := a.Write(d); err != nil {
+                                g.Panic(err)
+                        } else if num != len(d) {
+                                g.Panic(fmt.Errorf("Invalid write: %v != %v", num, len(d)))
+                        }
+                }
+        }
+}
+
+func (t *TestGroup) NewDualWriter(a1, a2 io.WriteCloser) io.WriteCloser {
+        c1 := make(chan []byte)
+        c2 := make(chan []byte)
+        r := &dualWriter{c1, c2}
+        t.Go("writer0", newWriter(c1, a1))
+        t.Go("writer1", newWriter(c2, a2))
+        return r
+}