Favor SomeClass === object over object.is_a?(SomeClass).

It seems more likely for users to mess with `is_a?` on
an individual object then `Class#===`, so it's better
to use the latter.

lib/rspec/mocks/any_instance/message_chains.rb

@@ -21,14 +21,14 @@ def add(method_name, chain)
         # @private
         def remove_stub_chains_for!(method_name)
           @chains_by_method_name[method_name].reject! do |chain|
-            chain.is_a?(StubChain)
+            StubChain === chain
           end
         end
 
         # @private
         def has_expectation?(method_name)
           @chains_by_method_name[method_name].find do |chain|
-            chain.is_a?(ExpectationChain)
+            ExpectationChain === chain
           end
         end
 
@@ -42,7 +42,7 @@ def all_expectations_fulfilled?
         # @private
         def unfulfilled_expectations
           @chains_by_method_name.map do |method_name, chains|
-            method_name.to_s if chains.last.is_a?(ExpectationChain) unless chains.last.expectation_fulfilled?
+            method_name.to_s if ExpectationChain === chains.last unless chains.last.expectation_fulfilled?
           end.compact
         end
 
@@ -64,8 +64,8 @@ def playback!(instance, method_name)
         private
 
         def raise_if_second_instance_to_receive_message(instance)
-          @instance_with_expectation ||= instance if instance.is_a?(ExpectationChain)
-          if instance.is_a?(ExpectationChain) && !@instance_with_expectation.equal?(instance)
+          @instance_with_expectation ||= instance if ExpectationChain === instance
+          if ExpectationChain === instance && !@instance_with_expectation.equal?(instance)
             raise RSpec::Mocks::MockExpectationError, "Exactly one instance should have received the following message(s) but didn't: #{unfulfilled_expectations.sort.join(', ')}"
           end
         end

lib/rspec/mocks/any_instance/recorder.rb

@@ -26,7 +26,7 @@ def initialize(klass)
         #
         # @see Methods#stub
         def stub(method_name_or_method_map, &block)
-          if method_name_or_method_map.is_a?(Hash)
+          if Hash === method_name_or_method_map
             method_name_or_method_map.each do |method_name, return_value|
               stub(method_name).and_return(return_value)
             end

lib/rspec/mocks/argument_list_matcher.rb

@@ -71,7 +71,7 @@ def args_match?(*args)
 
       def matcher_for(arg)
         return ArgumentMatchers::MatcherMatcher.new(arg) if is_matcher?(arg)
-        return ArgumentMatchers::RegexpMatcher.new(arg)  if arg.is_a?(Regexp)
+        return ArgumentMatchers::RegexpMatcher.new(arg)  if Regexp === arg
         return ArgumentMatchers::EqualityProxy.new(arg)
       end
 

lib/rspec/mocks/argument_matchers.rb

@@ -214,7 +214,7 @@ def hash_including(*args)
       #   object.should_receive(:message).with(array_including(1,2,3))
       #   object.should_receive(:message).with(array_including([1,2,3]))
       def array_including(*args)
-        actually_an_array = args.first.is_a?(Array) && args.count == 1 ? args.first : args
+        actually_an_array = Array === args.first && args.count == 1 ? args.first : args
         ArrayIncludingMatcher.new(actually_an_array)
       end
 

lib/rspec/mocks/error_generator.rb

@@ -77,11 +77,14 @@ def expected_part_of_expectation_error(expected_received_count, expectation_coun
 
       # @private
       def method_call_args_description(args)
-        if args.first.is_a?(ArgumentMatchers::AnyArgsMatcher)
-          " with any arguments"
-        elsif args.first.is_a?(ArgumentMatchers::NoArgsMatcher)
-          " with no arguments"
-        elsif args.length > 0
+        case args.first
+          when ArgumentMatchers::AnyArgsMatcher
+            return " with any arguments"
+          when ArgumentMatchers::NoArgsMatcher
+            return " with no arguments"
+       end
+
+        if args.length > 0
           " with arguments: #{args.inspect.gsub(/\A\[(.+)\]\z/, '(\1)')}"
         else
           ""

lib/rspec/mocks/instance_method_stasher.rb

@@ -88,7 +88,7 @@ def method_owned_by_klass?
         # On Ruby 2.0.0+ the owner of a method on a class which has been
         # `prepend`ed may actually be an instance, e.g.
         # `#<MyClass:0x007fbb94e3cd10>`, rather than the expected `MyClass`.
-        owner = owner.class unless owner.is_a? Module
+        owner = owner.class unless Module === owner
 
         # On some 1.9s (e.g. rubinius) aliased methods
         # can report the wrong owner. Example:

lib/rspec/mocks/message_expectation.rb

@@ -127,7 +127,7 @@ def yield_receiver_to_implementation_block?
       #   counter.increment
       #   expect(counter.count).to eq(original_count + 1)
       def and_call_original
-        if @method_double.object.is_a?(RSpec::Mocks::TestDouble)
+        if RSpec::Mocks::TestDouble === @method_double.object
           @error_generator.raise_only_valid_on_a_partial_mock(:and_call_original)
         else
           @implementation = AndCallOriginalImplementation.new(@method_double.original_method)

lib/rspec/mocks/mutate_const.rb

@@ -64,7 +64,7 @@ def recursive_const_get(const_name)
 
       def recursive_const_defined?(const_name)
         normalize_const_name(const_name).split('::').inject([Object, '']) do |(mod, full_name), name|
-          yield(full_name, name) if block_given? && !mod.is_a?(Module)
+          yield(full_name, name) if block_given? && !(Module === mod)
           return false unless const_defined_on?(mod, name)
           [get_const_defined_on(mod, name), [mod, name].join('::')]
         end
@@ -291,7 +291,7 @@ def verify_constants_to_transfer!
             end
           end
 
-          if @transfer_nested_constants.is_a?(Array)
+          if Array === @transfer_nested_constants
             @transfer_nested_constants = @transfer_nested_constants.map(&:to_s) if RUBY_VERSION == '1.8.7'
             undefined_constants = @transfer_nested_constants - constants_defined_on(@original_value)
 

lib/rspec/mocks/proxy.rb

@@ -159,7 +159,7 @@ def message_received(message, *args, &block)
         elsif stub = find_almost_matching_stub(message, *args)
           stub.advise(*args)
           raise_missing_default_stub_error(stub, *args)
-        elsif @object.is_a?(Class)
+        elsif Class === @object
           @object.superclass.__send__(message, *args, &block)
         else
           @object.__send__(:method_missing, message, *args, &block)

lib/rspec/mocks/test_double.rb

@@ -68,7 +68,7 @@ def __build_mock_proxy
     private
 
       def __initialize_as_test_double(name=nil, stubs={})
-        if name.is_a?(Hash) && stubs.empty?
+        if Hash === name && stubs.empty?
           stubs = name
           @name = nil
         else