1 files changed, 78 insertions, 0 deletions
diff --git a/pipeln.go b/pipeln.go
new file mode 100644
index 0000000..8ff6a62
--- /dev/null
+++ b/pipeln.go
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: CC0-1.0
+
+package pipeln
+
+import (
+	"context"
+	"errors"
+	"net"
+)
+
+var (
+	ErrBadAddress = errors.New("bad address")
+	ErrClosed     = errors.New("closed listener")
+)
+
+type addr struct {
+	ln *PipeListenerDialer
+}
+
+var _ net.Addr = addr{}
+
+func (addr) Network() string {
+	return "pipe"
+}
+
+func (a addr) String() string {
+	return "pipe:" + a.ln.addr
+}
+
+// PipeListener can be used to simulate client-server interaction within
+// the same process. Useful for testing. Somehow the Go standard library
+// provides net.Pipe but no net.PipeListener.
+type PipeListenerDialer struct {
+	addr  string
+	conns chan net.Conn
+	done  chan struct{}
+}
+
+var _ net.Listener = &PipeListenerDialer{}
+
+func (ln *PipeListenerDialer) Accept() (net.Conn, error) {
+	select {
+	case conn := <-ln.conns:
+		return conn, nil
+	case <-ln.done:
+		return nil, ErrClosed
+	}
+}
+
+func (ln *PipeListenerDialer) Addr() net.Addr {
+	return addr{ln}
+}
+
+func (ln *PipeListenerDialer) Close() error {
+	close(ln.done)
+	return nil
+}
+
+func (ln *PipeListenerDialer) Dial(_, addr string) (net.Conn, error) {
+	if addr != ln.addr {
+		return nil, ErrBadAddress
+	}
+	s, c := net.Pipe()
+	select {
+	case <-ln.done:
+		return nil, ErrClosed
+	case ln.conns <- s:
+		return c, nil
+	}
+}
+
+func (ln *PipeListenerDialer) DialContext(_ context.Context, network, addr string) (net.Conn, error) {
+	return ln.Dial(network, addr)
+}
+
+func New(addr string) *PipeListenerDialer {
+	return &PipeListenerDialer{addr, make(chan net.Conn), make(chan struct{})}
+}