How to use custom RR wildcard matcher? - ruby

Question

I have created a wildcard matcher for RR that matches JSON strings by parsing them into hashes. This is because JSON (de)serialization doesn't preserve order; if we have:
{ 'foo': 42, 'bar': 123 }
... then after (de)serialization, we might find that our update method is called with:
{ 'bar': 123, 'foo': 42 }
The wildcard matcher looks like this:
class RR::WildcardMatchers::MatchesJsonString
attr_reader :expected_json_hash
def initialize(expected_json_string)
#expected_json_hash = JSON.parse(expected_json_string)
end
def ==(other)
other.respond_to?(:expected_json_hash) && other.expected_json_hash == self.expected_json_hash
end
def wildcard_matches?(actual_json_string)
actual_json_hash = JSON.parse(actual_json_string)
#expected_json_hash == actual_json_hash
end
end
module RR::Adapters::RRMethods
def matches_json(expected_json_string)
RR::WildcardMatchers::MatchesJsonString.new(expected_json_string)
end
end
... and we're using it like:
describe 'saving manifests' do
before do
#manifests = [
{ :sections => [], 'title' => 'manifest1' },
{ :sections => [], 'title' => 'manifest2' }
]
mock(manifest).create_or_update!(matches_json(#manifests[0].to_json)) { raise 'uh oh' }
mock(manifest).create_or_update!(matches_json(#manifests[1].to_json))
parser = ContentPack::ContentPackParser.new({
'manifests' => #manifests
})
#errors = parser.save
end
it 'updates manifests' do
manifest.should have_received.create_or_update!(anything).twice
end
end
This in accordance with the RR documentation. However, instead of mock() expecting an argument that matches JSON, it expects the argument to be a MatchesJsonString object:
1) ContentPack::ContentPackParser saving manifests updates manifests
Failure/Error: mock(Manifest).create_or_update!(matches_json(#manifests[0].to_json)) { raise 'uh oh' }
RR::Errors::TimesCalledError:
create_or_update!(#<RR::WildcardMatchers::MatchesJsonString:0x13540def0 #expected_json_hash={"title"=>"manifest1", "sections"=>[]}>)
Called 0 times.
Expected 1 times.
# ./spec/models/content_pack/content_pack_parser_spec.rb:196

Answer 1

The answer is that there's a typo in the documentation to which I linked. This (my emphasis):
#wildcard_matches?(other)
wildcard_matches? is the method that actually checks the argument against the expectation. It should return true if other is considered to match, false otherwise. In the case of DivisibleBy, wildcard_matches? reads:
... should actually read:
#wildcard_match?(other)
...
One of my colleagues suggested that we compare our code with one of the matchers defined in the rr gem, and then the difference stood out.