def render(source, context, helpers=None, partials=None, knownHelpers=None,
knownHelpersOnly=False):
compiler = Compiler('casper')
template = compiler.compile(source)
# For real use, partials is a dict of compiled templates; but for testing
# we compile just-in-time.
if not partials:
real_partials = None
else:
real_partials = dict((key, compiler.compile(value))
for key, value in list(partials.items()))
return str_class(template(context, helpers=helpers, partials=real_partials))