function createExpectedRoleObject(role) {
        var valid = (axs.constants.ARIA_ROLES.hasOwnProperty(role) && !axs.constants.ARIA_ROLES[role]['abstract']);
        var result = { name: role, valid: valid };
        if (valid) {
            result.details = axs.constants.ARIA_ROLES[role];
        }
        return result;
    }
Creates a 'role detail' object which can be used for comparison in the assertions below.
@param {!string} role A potential ARIA role.
@return The 'role detail' object.