Add '--xxx' only argument type for client cli

Beside the command type "<client> --key=<value> <command>", there is
other type of command type "<client> --key <command>" for example
"keystone --insecure tenant-list". Add this command argument type
into consideration.

Change-Id: I6bb97279ef380eb71ac581f8cd99623ab7d1519e

CHANGELOG.md

@@ -6,6 +6,7 @@ This file is used to list changes made in each version of cookbook-openstack-com
 * Separate endpoints for vncserver_listen and vncserver_proxyclient_address
 * Bump Chef gem to 11.16
 * Fix openstack_command with correct arguments order
+* Fix openstack_command with single argument type
 
 ## 10.1.0
 * Adding identity admin bind host endpoint to allow flexibility and consistency

libraries/cli.rb

@@ -56,7 +56,8 @@ module ::Openstack # rubocop:disable Documentation
     #       glance   image-show <id|name>
     openstackcmd = [cmd]
     args.each do |key, val|
-      openstackcmd << "--#{key}" << val.to_s
+      openstackcmd << "--#{key}"
+      openstackcmd << val.to_s unless val.to_s.empty?
     end
     openstackcmd = openstackcmd.concat(options.split)
     Chef::Log.debug("Running openstack command: #{openstackcmd} with environment: #{env}")

spec/cli_spec.rb

@@ -57,11 +57,11 @@ describe 'openstack-common::default' do
             'OS_AUTH_URL' => 'http://127.0.0.1:35357/v2.0'
           }
         allow(subject).to receive(:shell_out).with(
-          %w(keystone --key1 value1 --key2 value2 user-list),
+          %w(keystone --key1 value1 --key2 value2 --key3 user-list),
           env: env
           ).and_return double('shell_out', exitstatus: 0, stdout: 'good', stderr: '')
 
-        result = subject.openstack_command('keystone', 'user-list', env, 'key1' => 'value1', 'key2' => 'value2')
+        result = subject.openstack_command('keystone', 'user-list', env, 'key1' => 'value1', 'key2' => 'value2', 'key3' => '')
         expect(result).to eq('good')
       end