Merge pull request #1470 from eregon/better-check-for-Class-new

Use a better and more reliable check for whether a method is the same as Class#new

lib/rspec/mocks/method_reference.rb

@@ -185,11 +185,23 @@ class ClassNewMethodReference < ObjectMethodReference
       def self.applies_to?(method_name)
         return false unless method_name == :new
         klass = yield
-        return false unless klass.respond_to?(:new, true)
+        return false unless ::Class === klass && klass.respond_to?(:new, true)
 
         # We only want to apply our special logic to normal `new` methods.
         # Methods that the user has monkeyed with should be left as-is.
-        ::RSpec::Support.method_handle_for(klass, :new).owner == ::Class
+        uses_class_new?(klass)
+      end
+
+      if RUBY_VERSION.to_i >= 3
+        CLASS_NEW = ::Class.singleton_class.instance_method(:new)
+
+        def self.uses_class_new?(klass)
+          ::RSpec::Support.method_handle_for(klass, :new) == CLASS_NEW.bind(klass)
+        end
+      else # Ruby 2's Method#== is too strict
+        def self.uses_class_new?(klass)
+          ::RSpec::Support.method_handle_for(klass, :new).owner == ::Class
+        end
       end
 
       def with_signature

spec/rspec/mocks/partial_double_spec.rb

@@ -622,6 +622,20 @@ class << self
           end
         end
 
+        context "on a class with a twice-aliased `new`" do
+          it 'uses the method signature from `#initialize` for arg verification', :if => (RUBY_VERSION.to_i >= 3) do
+            subclass = Class.new(klass) do
+              class << self
+                alias_method :_new, :new
+                alias_method :new, :_new
+              end
+            end
+
+            prevents(/arguments/) { allow(subclass).to receive(:new).with(1) }
+            allow(subclass).to receive(:new).with(1, 2)
+          end
+        end
+
         context 'on a class that has redefined `self.method`' do
           it 'allows the stubbing of :new' do
             subclass = Class.new(klass) do