lib/model, lib/testutils: Test closing a connection on folder restart (#5707)

lib/testutils/testutils.go

@@ -0,0 +1,31 @@
+// Copyright (C) 2019 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package testutils
+
+// BlockingRW implements io.Reader and Writer but never returns when called
+type BlockingRW struct{ nilChan chan struct{} }
+
+func (rw *BlockingRW) Read(p []byte) (n int, err error) {
+	<-rw.nilChan
+	return
+}
+
+func (rw *BlockingRW) Write(p []byte) (n int, err error) {
+	<-rw.nilChan
+	return
+}
+
+// NoopRW implements io.Reader and Writer but never returns when called
+type NoopRW struct{}
+
+func (rw *NoopRW) Read(p []byte) (n int, err error) {
+	return len(p), nil
+}
+
+func (rw *NoopRW) Write(p []byte) (n int, err error) {
+	return len(p), nil
+}