range type expression syntax

Seems I'm missing a trick trying to get rangetypes working:

No problem building the string:
select concat('''[', now()::date, ',', now()::date, ']''') testrange;
           testrange
---------------------------
  '[2015-02-26,2015-02-26]'
(1 row)

Bombed-out trying to turn this into a daterange:
postgres=# select concat('''[', now()::date, ',', now()::date,
']''')::daterange testrange;
ERROR:  malformed range literal: "'[2015-02-26,2015-02-26]'"
DETAIL:  Missing left parenthesis or bracket.

Is there a specific casting I need to apply in order to render a literal
daterange from parameterized range elements?

/john