Add unit test for sync pipe

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)

namespaces/sync_pipe.go

@@ -24,6 +24,7 @@ func NewSyncPipe() (s *SyncPipe, err error) {
 	if err != nil {
 		return nil, err
 	}
+
 	s.child = os.NewFile(uintptr(fds[0]), "child syncpipe")
 	s.parent = os.NewFile(uintptr(fds[1]), "parent syncpipe")
 
@@ -32,6 +33,7 @@ func NewSyncPipe() (s *SyncPipe, err error) {
 
 func NewSyncPipeFromFd(parendFd, childFd uintptr) (*SyncPipe, error) {
 	s := &SyncPipe{}
+
 	if parendFd > 0 {
 		s.parent = os.NewFile(parendFd, "parendPipe")
 	} else if childFd > 0 {
@@ -39,6 +41,7 @@ func NewSyncPipeFromFd(parendFd, childFd uintptr) (*SyncPipe, error) {
 	} else {
 		return nil, fmt.Errorf("no valid sync pipe fd specified")
 	}
+
 	return s, nil
 }
 
@@ -65,9 +68,11 @@ func (s *SyncPipe) ReadFromChild() error {
 	if err != nil {
 		return err
 	}
+
 	if len(data) > 0 {
-		return fmt.Errorf("Child error: %s", string(data))
+		return fmt.Errorf("%s", data)
 	}
+
 	return nil
 }
 
@@ -83,7 +88,6 @@ func (s *SyncPipe) ReadFromParent() (*network.NetworkState, error) {
 		}
 	}
 	return networkState, nil
-
 }
 
 func (s *SyncPipe) ReportChildError(err error) {
@@ -95,9 +99,11 @@ func (s *SyncPipe) Close() error {
 	if s.parent != nil {
 		s.parent.Close()
 	}
+
 	if s.child != nil {
 		s.child.Close()
 	}
+
 	return nil
 }
 

namespaces/sync_pipe_test.go

@@ -0,0 +1,63 @@
+package namespaces
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestSendErrorFromChild(t *testing.T) {
+	pipe, err := NewSyncPipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		if err := pipe.Close(); err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	expected := "something bad happened"
+
+	pipe.ReportChildError(fmt.Errorf(expected))
+
+	childError := pipe.ReadFromChild()
+	if childError == nil {
+		t.Fatal("expected an error to be returned but did not receive anything")
+	}
+
+	if childError.Error() != expected {
+		t.Fatalf("expected %q but received error message %q", expected, childError.Error())
+	}
+}
+
+func TestSendPayloadToChild(t *testing.T) {
+	pipe, err := NewSyncPipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() {
+		if err := pipe.Close(); err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	expected := "libcontainer"
+
+	if err := pipe.SendToChild(map[string]string{"name": expected}); err != nil {
+		t.Fatal(err)
+	}
+
+	payload, err := pipe.ReadFromParent()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(payload) != 1 {
+		t.Fatalf("expected to only have one value in the payload but received %d", len(payload))
+	}
+
+	if name := payload["name"]; name != expected {
+		t.Fatalf("expected name %q but received %q", expected, name)
+	}
+}