why can't I use assert_respond_to with some objects?

[Rob Sanheim]

Hi

This question is w/i the context of Rails, but I think it relates more
to how pretty printer works then Rails.

I'm extending the built in AbstractRequest class in Rails, and trying
to test it. The following test errors out, when it should be failing
(as I haven't added the method yet):

def test_should_have_site_subdomain
@request = ActionController::AbstractRequest.new
assert_respond_to @request, :site_subdomain
end

with this exception:

1) Error:
test_should_have_site_subdomain(RailsExtensionsTest):
ArgumentError: wrong number of arguments (1 for 0)
method method in pp.rb at line 244
method pretty_print in pp.rb at line 244
method pp in pp.rb at line 126
method group in prettyprint.rb at line 224
method nest in prettyprint.rb at line 247
method group in prettyprint.rb at line 223
method group_sub in prettyprint.rb at line 235
method group in prettyprint.rb at line 222
method pp in pp.rb at line 126
method pp in pp.rb at line 69
method guard_inspect_key in pp.rb at line 105
method pp in pp.rb at line 69
method test_should_have_site_subdomain in rails_extensions_test.rb at line 18
method run in test_case_adapter.rb at line 19

So its trying to call pp with an invalid call, but I get pretty lost
trying to figure out how it got there. Note that the test passes and
everything is fine after I add the method, so this isn't a huge issue
-- I would just like to have the correct failure, and not a strange
prettyprint error, when this does fail.

assert_respond_to fails correctly if I just test a builtin, btw, like so:

def test_string
assert_respond_to 'string', :foo
end

with
1) Failure:
test_string(RailsExtensionsTest)
method test_string in rails_extensions_test.rb at line 22
method run in test_case_adapter.rb at line 19
<"string"> of type <String> expected to respond_to?<:foo>.

thanks,
- Rob