Attempt to set last argument on the object itself

lib/mocha/parameter_matchers/base.rb

@@ -3,7 +3,7 @@ module ParameterMatchers
     # @abstract Subclass and implement +#matches?+ and +#mocha_inspect+ to define a custom matcher. Also add a suitably named instance method to {ParameterMatchers} to build an instance of the new matcher c.f. {#equals}.
     class Base
       # @private
-      def to_matcher(*)
+      def to_matcher
         self
       end
 

lib/mocha/parameter_matchers/instance_methods.rb

@@ -5,9 +5,17 @@ module ParameterMatchers
     # @private
     module InstanceMethods
       # @private
-      def to_matcher(*)
+      def to_matcher
         Mocha::ParameterMatchers::Equals.new(self)
       end
+
+      def mark_last_argument
+        @is_last_argument = true
+      end
+
+      def is_last_argument?
+        !!@is_last_argument
+      end
     end
   end
 end
@@ -19,8 +27,9 @@ class Object
 
 # @private
 class Hash
-  def to_matcher(last_argument: false)
-    return Mocha::ParameterMatchers::LastPositionalHash.new(self) if last_argument
+  # @private
+  def to_matcher
+    return Mocha::ParameterMatchers::LastPositionalHash.new(self) if is_last_argument?
 
     super
   end

lib/mocha/parameters_matcher.rb

@@ -29,7 +29,8 @@ def mocha_inspect
     end
 
     def matchers
-      @expected_parameters[0...-1].map(&:to_matcher) + [@expected_parameters.last.to_matcher(last_argument: true)]
+      @expected_parameters.last.mark_last_argument
+      @expected_parameters.map(&:to_matcher)
     end
   end
 end

test/unit/parameter_matchers/stub_matcher.rb

@@ -16,7 +16,7 @@ def mocha_inspect
       "matcher(#{@matches})"
     end
 
-    def to_matcher(*)
+    def to_matcher
       self
     end
   end