Do you mean the first or the second unittest ?
The first test is simply a property-value that has been entered but not *closed* by semicolon. In this case the CSS hint provider should not present any hints. (I think this unittest was a bit different in a previous version - this needs to be moved and renamed to the getHints/hasHints testsuite).

The second test happens if you write the whole prop-name and hit enter. In this case the hintlist should can contain only one hint (sometimes more if the prop-name is a shortcut like *border* and all its variations). In any case by hitting 'Enter' only the colon should be added. (Here: color is used as prop-value thus only the semicolon is added)