Make Oj adapter handle JSON::ParseError correctly

Author: rwz

lib/multi_json/adapters/oj.rb

@@ -8,7 +8,25 @@ class Oj < Adapter
       defaults :load, :mode => :strict, :symbolize_keys => false
       defaults :dump, :mode => :compat, :time_format => :ruby, :use_to_json => true
 
-      ParseError = defined?(::Oj::ParseError) ? ::Oj::ParseError : SyntaxError
+      # In certain cases OJ gem may throw JSON::ParserError exception instead
+      # of its own class. Also, we can't expect ::JSON::ParserError and
+      # ::Oj::ParseError to always be defined, since it's often not the case.
+      # Because of this, we can't reference those classes directly and have to
+      # do string comparison instead. This will not catch subclasses, but it
+      # shouldn't be a problem since the library is not known to be using it
+      # (at least for now).
+      class ParseError < ::SyntaxError
+        WRAPPED_CLASSES = %w[Oj::ParseError JSON::ParserError].to_set.freeze
+
+        def self.===(exception)
+          case exception
+          when ::SyntaxError
+            true
+          else
+            WRAPPED_CLASSES.include?(exception.class.to_s)
+          end
+        end
+      end
 
       def load(string, options = {})
         options[:symbol_keys] = options[:symbolize_keys]

spec/shared/adapter.rb

@@ -169,12 +169,13 @@ def to_json(*)
       expect(MultiJson.load('{"abc":"def"}')).to eq('abc' => 'def')
     end
 
-    it 'raises MultiJson::ParseError on blank input or invalid input' do
-      [nil, '{"abc"}', ' ', "\t\t\t", "\n", "\x82\xAC\xEF", StringIO.new('')].each do |input|
-        if input == "\x82\xAC\xEF"
-          pending 'GSON bug: https://github.com/avsej/gson.rb/issues/3' if adapter.name =~ /Gson/
-        end
+    examples = [nil, '{"abc"}', ' ', "\t\t\t", "\n", StringIO.new('')]
+    #
+    # GSON bug: https://github.com/avsej/gson.rb/issues/3
+    examples << "\x82\xAC\xEF" unless adapter.name =~ /Gson/
 
+    examples.each do |input|
+      it "raises MultiJson::ParseError on invalid input: #{input.inspect}" do
         expect { MultiJson.load(input) }.to raise_error(MultiJson::ParseError)
       end
     end
@@ -183,21 +184,21 @@ def to_json(*)
       data = '{invalid}'
       exception = get_exception(MultiJson::ParseError) { MultiJson.load data }
       expect(exception.data).to eq(data)
-      expect(exception.cause).to be_kind_of(MultiJson.adapter::ParseError)
+      expect(exception.cause).to match(MultiJson.adapter::ParseError)
     end
 
     it 'catches MultiJson::DecodeError for legacy support' do
       data = '{invalid}'
       exception = get_exception(MultiJson::DecodeError) { MultiJson.load data }
       expect(exception.data).to eq(data)
-      expect(exception.cause).to be_kind_of(MultiJson.adapter::ParseError)
+      expect(exception.cause).to match(MultiJson.adapter::ParseError)
     end
 
     it 'catches MultiJson::LoadError for legacy support' do
       data = '{invalid}'
       exception = get_exception(MultiJson::LoadError) { MultiJson.load data }
       expect(exception.data).to eq(data)
-      expect(exception.cause).to be_kind_of(MultiJson.adapter::ParseError)
+      expect(exception.cause).to match(MultiJson.adapter::ParseError)
     end
 
     it 'stringifys symbol keys when encoding' do