How to use VoiceOver to test the a11y of a combobox element

I am not sure if this is the way as it should work. I found no information about it. I tested it on a combobox example from w3org and that is how it worked.

• Ctrl+Option+Right arrow to move to the combobox.
• Ctrl+Option+Space to open the options list (VoiceOver should announce that the list is expanded).
• Down arrow to move into the option list (VoiceOver should announce the first list element).
• Enter to select an item (VoiceOver should announce that the element is selected and the list is collapsed).
• Ctrl+Option+Right arrow to move to the next form item

I do not know (yet) how the search option of the combobox should be used correctly.