I hate having to hunt through redirect responses. With the help of Chris McGrath, who wrote the diff function, and told me how to rescue an assertion, here's a nicer assert_redirected_to message.
assert_redirected_to :action => 'other_host', :only_path => false
when it was expecting
redirected_to :action => 'other_host', :only_path => true, :host => 'other.test.host'
gives the error message
response is not a redirection to all of the options supplied (redirection is <{:only_path=>false, :host=>"other.test.host", :action=>"other_host"}>), difference: <{:only_path=>"true", :host=>"other.test.host"}>
which is much nicer IMO. With full tests.