Show proof of concept for keyword arg matching

.rubocop.yml

@@ -11,6 +11,10 @@ Style/Alias:
 Style/Documentation:
   Enabled: false
 
+# Useful for distinuishing between positional & keyword arguments
+Style/BracesAroundHashParameters:
+  Enabled: false
+
 # Enumerable#each_with_object only available since Ruby v1.9
 Style/EachWithObject:
   Enabled: false

lib/mocha/expectation.rb

@@ -1,3 +1,4 @@
+require 'mocha/ruby_version'
 require 'mocha/method_matcher'
 require 'mocha/parameters_matcher'
 require 'mocha/expectation_error'
@@ -222,6 +223,7 @@ def with(*expected_parameters, &matching_block)
       @parameters_matcher = ParametersMatcher.new(expected_parameters, &matching_block)
       self
     end
+    ruby2_keywords(:with) if RUBY_V3_PLUS
 
     # Modifies expectation so that the expected method must be called with a block.
     #

lib/mocha/invocation.rb

@@ -18,6 +18,7 @@ def initialize(mock, method_name, *arguments, &block)
       @yields = []
       @result = nil
     end
+    ruby2_keywords(:initialize) if RUBY_V3_PLUS
 
     def call(yield_parameters = YieldParameters.new, return_values = ReturnValues.new)
       yield_parameters.next_invocation.each do |yield_args|

lib/mocha/mock.rb

@@ -1,3 +1,4 @@
+require 'mocha/ruby_version'
 require 'mocha/expectation'
 require 'mocha/expectation_list'
 require 'mocha/invocation'
@@ -318,6 +319,7 @@ def method_missing(symbol, *arguments, &block) # rubocop:disable Style/MethodMis
         raise_unexpected_invocation_error(invocation, matching_expectation)
       end
     end
+    ruby2_keywords(:method_missing) if RUBY_V3_PLUS
 
     # @private
     def respond_to_missing?(symbol, include_all)

lib/mocha/parameter_matchers/last_positional_hash.rb

@@ -0,0 +1,26 @@
+require 'mocha/parameter_matchers/base'
+require 'mocha/ruby_version'
+
+module Mocha
+  module ParameterMatchers
+    # @private
+    class LastPositionalHash < Base
+      def initialize(value)
+        @value = value
+      end
+
+      def matches?(available_parameters)
+        parameter = available_parameters.shift
+        if RUBY_V3_PLUS
+          return false unless Hash.ruby2_keywords_hash?(@value) == Hash.ruby2_keywords_hash?(parameter)
+        end
+
+        parameter == @value
+      end
+
+      def mocha_inspect
+        @value.mocha_inspect
+      end
+    end
+  end
+end

lib/mocha/parameters_matcher.rb

@@ -1,5 +1,6 @@
 require 'mocha/inspect'
 require 'mocha/parameter_matchers'
+require 'mocha/parameter_matchers/last_positional_hash'
 
 module Mocha
   class ParametersMatcher
@@ -28,7 +29,11 @@ def mocha_inspect
     end
 
     def matchers
-      @expected_parameters.map(&:to_matcher)
+      if (last_parameter = @expected_parameters.last).is_a?(Hash)
+        @expected_parameters[0...-1].map(&:to_matcher) + [ParameterMatchers::LastPositionalHash.new(last_parameter)]
+      else
+        @expected_parameters.map(&:to_matcher)
+      end
     end
   end
 end

lib/mocha/ruby_version.rb

@@ -1,3 +1,4 @@
 module Mocha
   RUBY_V2_PLUS = Gem::Version.new(RUBY_VERSION.dup) >= Gem::Version.new('2')
+  RUBY_V3_PLUS = Gem::Version.new(RUBY_VERSION.dup) >= Gem::Version.new('3')
 end

lib/mocha/stubbed_method.rb

@@ -59,6 +59,7 @@ def define_new_method
       stub_method_owner.send(:define_method, method_name) do |*args, &block|
         self_in_scope.mock.method_missing(method_name_in_scope, *args, &block)
       end
+      stub_method_owner.send(:ruby2_keywords, method_name) if RUBY_V3_PLUS
       retain_original_visibility(stub_method_owner)
     end
 

test/unit/expectation_test.rb

@@ -1,4 +1,5 @@
 require File.expand_path('../../test_helper', __FILE__)
+require 'mocha/ruby_version'
 require 'mocha/expectation'
 require 'mocha/invocation'
 require 'mocha/sequence'
@@ -67,6 +68,28 @@ def test_should_not_match_calls_to_same_method_with_parameters_not_constrained_a
     assert !expectation.match?(Invocation.new(:irrelevant, :expected_method, 1, 0, 3))
   end
 
+  def test_should_match_last_positional_hash
+    expectation = new_expectation.with(1, { :a => 1 })
+    assert expectation.match?(Invocation.new(:irrelevant, :expected_method, 1, { :a => 1 }))
+  end
+
+  if RUBY_V3_PLUS
+    def test_should_match_keyword_args
+      expectation = new_expectation.with(1, Hash.ruby2_keywords_hash({ :a => 1 }))
+      assert expectation.match?(Invocation.new(:irrelevant, :expected_method, 1, Hash.ruby2_keywords_hash({ :a => 1 })))
+    end
+
+    def test_should_not_match_keyword_args_with_last_positional_hashes
+      expectation = new_expectation.with(1, Hash.ruby2_keywords_hash({ :a => 1 }))
+      assert !expectation.match?(Invocation.new(:irrelevant, :expected_method, 1, { :a => 1 }))
+    end
+
+    def test_should_not_match_last_positional_hashes_with_keyword_args
+      expectation = new_expectation.with(1, { :a => 1 })
+      assert !expectation.match?(Invocation.new(:irrelevant, :expected_method, 1, Hash.ruby2_keywords_hash({ :a => 1 })))
+    end
+  end
+
   def test_should_allow_invocations_until_expected_invocation_count_is_one_and_actual_invocation_count_would_be_two
     expectation = new_expectation.times(1)
     assert expectation.invocations_allowed?