fix tests

connection_test.go

diff --git a/connection_test.go b/connection_test.go
index c59cb61..6f8d2a6 100644
--- a/connection_test.go
+++ b/connection_test.go
@@ -163,6 +163,8 @@
 		netConn:          nc,
 		buf:              newBuffer(nc),
 		maxAllowedPacket: defaultMaxAllowedPacket,
+		closech:          make(chan struct{}),
+		cfg:              NewConfig(),
 	}
 
 	err := mc.Ping(context.Background())
@@ -184,8 +186,8 @@
 
 	err := mc.Ping(context.Background())
 
-	if err != ErrInvalidConn {
-		t.Errorf("expected ErrInvalidConn, got  %#v", err)
+	if err != nc.err {
+		t.Errorf("expected %#v, got  %#v", nc.err, err)
 	}
 }