cli: Fix logout when specifying a registry

Signed-off-by: Christopher Crone <christopher.crone@docker.com>

cli/cmd/logout/logout.go

@@ -12,7 +12,7 @@ func Command() *cobra.Command {
 		Use:   "logout [SERVER]",
 		Short: "Log out from a Docker registry or cloud backend",
 		Long:  "Log out from a Docker registry or cloud backend.\nIf no server is specified, the default is defined by the daemon.",
-		Args:  cobra.MaximumNArgs(0),
+		Args:  cobra.MaximumNArgs(1),
 		RunE:  runLogout,
 	}
 

tests/e2e/e2e_test.go

@@ -133,6 +133,9 @@ func (s *E2eSuite) TestClassicLogin() {
 	output, err := s.NewDockerCommand("login", "someregistry.docker.io").Exec()
 	Expect(output).To(ContainSubstring("Cannot perform an interactive login from a non TTY device"))
 	Expect(err).NotTo(BeNil())
+	output, err = s.NewDockerCommand("logout", "someregistry.docker.io").Exec()
+	Expect(output).To(ContainSubstring("Removing login credentials for someregistry.docker.io"))
+	Expect(err).To(BeNil())
 }
 
 func (s *E2eSuite) TestCloudLogin() {