acceptance: update serverspec syntax

Since we unpin beaker, serverspec is now 2.18.0 (before it was 1.16.0)
so we need to update some syntax to make the tests work.

Change-Id: Ie097f951123501f42e1a85abb81d2de556c4f749

spec/acceptance/mysql_spec.rb

@@ -25,8 +25,10 @@ describe 'openstacklib mysql' do
       it { is_expected.to be_listening.with('tcp') }
     end
 
-    describe command("mysql -e 'show databases;' | grep -q beaker") do
-      it { should return_exit_status 0 }
+    describe 'test database listing' do
+      it 'should list beaker database' do
+        expect(shell("mysql -e 'show databases;'|grep -q beaker").exit_code).to be_zero
+      end
     end
 
   end

spec/acceptance/rabbitmq_spec.rb

@@ -47,13 +47,19 @@ describe 'openstacklib class' do
       apply_manifest(pp, :catch_changes => true)
     end
 
-    describe command("rabbitmqctl list_users") do
-      it { should return_stdout /^beaker/ }
-      it { should_not return_stdout /^guest/ }
+    describe 'test rabbitmq resources' do
+      it 'should list rabbitmq beaker resources' do
+        shell('rabbitmqctl list_users') do |r|
+          expect(r.stdout).to match(/^beaker/)
+          expect(r.stdout).not_to match(/^guest/)
+          expect(r.exit_code).to eq(0)
         end
 
-    describe command('rabbitmqctl list_permissions') do
-      it { should return_stdout /^beaker\t\.\*\t\.\*\t\.\*$/ }
+        shell('rabbitmqctl list_permissions') do |r|
+          expect(r.stdout).to match(/^beaker\t\.\*\t\.\*\t\.\*$/)
+          expect(r.exit_code).to eq(0)
+        end
+      end
     end
 
   end