all: fix errcheck findings in new test code

Silence golangci-lint errcheck warnings for unchecked return values
in the new streamlocal and tcpip forwarding tests.

Updates gliderlabs#196

Author: kradalby

streamlocal_test.go

@@ -61,8 +61,8 @@ func sampleUnixSocketServer(t *testing.T) net.Listener {
 		if err != nil {
 			return
 		}
-		conn.Write(sampleServerResponse)
-		conn.Close()
+		_, _ = conn.Write(sampleServerResponse)
+		_ = conn.Close()
 	}()
 
 	return l
@@ -87,7 +87,7 @@ func newTestSessionWithUnixForwarding(t *testing.T, forwardingEnabled bool) (net
 
 	return l, client, func() {
 		cleanup()
-		l.Close()
+		_ = l.Close()
 	}
 }
 
@@ -149,14 +149,14 @@ func TestReverseUnixForwardingWorks(t *testing.T) {
 	if err != nil {
 		t.Fatalf("failed to listen on a unix socket over SSH %q: %v", remoteSocketPath, err)
 	}
-	defer l.Close()
+	defer l.Close() //nolint:errcheck
 	go func() {
 		conn, err := l.Accept()
 		if err != nil {
 			return
 		}
-		conn.Write(sampleServerResponse)
-		conn.Close()
+		_, _ = conn.Write(sampleServerResponse)
+		_ = conn.Close()
 	}()
 
 	// Dial the listener that should've been created by the server.

tcpip_test.go

@@ -106,14 +106,14 @@ func TestReverseTCPForwardingWorks(t *testing.T) {
 	if err != nil {
 		t.Fatalf("failed to listen on a random TCP port over SSH: %v", err)
 	}
-	defer l.Close()
+	defer l.Close() //nolint:errcheck
 	go func() {
 		conn, err := l.Accept()
 		if err != nil {
 			return
 		}
-		conn.Write(sampleServerResponse)
-		conn.Close()
+		_, _ = conn.Write(sampleServerResponse)
+		_ = conn.Close()
 	}()
 
 	// Dial the listener that should've been created by the server.