##### SUMMARY

Add integration tests for the varnames lookup plugin.

##### ISSUE TYPE

Feature Idea

##### COMPONENT NAME

varnames lookup plugin

def run(self, terms, variables=None, **kwargs):
        if variables is None:
            raise AnsibleError('No variables available to search')
        
        
        ret = []
        variable_names = list(variables.keys())
        for term in terms:
            if not isinstance(term, string_types):
                raise AnsibleError('Invalid setting identifier, "%s" is not a string, its a %s' % (term, type(term)))
            try:
                name = re.compile(term)
            except Exception as e:
                raise AnsibleError('Unable to use "%s" as a search parameter: %s' % (term, to_native(e)))
            for varname in variable_names:
                if name.search(varname):
                    ret.append(varname)
        return ret