2 files changed, 136 insertions, 0 deletions
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index 66251b9fb0..797ae95e97 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -1114,6 +1114,33 @@ class TestArray < Test::Unit::TestCase
     assert_not_include(a, [1,2])
   end
 
+  def test_monkey_patch_include?
+    assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}", timeout: 30)
+    begin;
+      $-w = false
+      class Array
+        alias :old_include? :include?
+        def include? x
+          return true if x == :always
+          old_include?(x)
+        end
+      end
+      def test
+        a, c, always = :a, :c, :always
+        [
+          [:a, :b].include?(a),
+          [:a, :b].include?(c),
+          [:a, :b].include?(always),
+        ]
+      end
+      v = test
+      class Array
+        alias :include? :old_include?
+      end
+      assert_equal [true, false, true], v
+    end;
+  end
+
   def test_intersect?
     a = @cls[ 1, 2, 3]
     assert_send([a, :intersect?, [3]])
diff --git a/test/ruby/test_optimization.rb b/test/ruby/test_optimization.rb
index 982da661ec..5aaf9647a8 100644
--- a/test/ruby/test_optimization.rb
+++ b/test/ruby/test_optimization.rb
@@ -1107,4 +1107,113 @@ class TestRubyOptimization < Test::Unit::TestCase
     def o.to_s; 1; end
     assert_match %r{\A#<Object:0x[0-9a-f]+>\z}, "#{o}"
   end
+
+  def test_opt_duparray_send_include_p
+    [
+      'x = :b; [:a, :b].include?(x)',
+      '@c = :b; [:a, :b].include?(@c)',
+      '@c = "b"; %i[a b].include?(@c.to_sym)',
+      '[:a, :b].include?(self) == false',
+    ].each do |code|
+      iseq = RubyVM::InstructionSequence.compile(code)
+      insn = iseq.disasm
+      assert_match(/opt_duparray_send/, insn)
+      assert_no_match(/\bduparray\b/, insn)
+      assert_equal(true, eval(code))
+    end
+
+    x, y = :b, :c
+    assert_equal(true,  [:a, :b].include?(x))
+    assert_equal(false, [:a, :b].include?(y))
+
+    assert_in_out_err([], <<~RUBY, ["1,2", "3,3", "1,2", "4,4"])
+      class Array
+        prepend(Module.new do
+          def include?(i)
+            puts self.join(",")
+            # Modify self to prove that we are operating on a copy.
+            map! { i }
+            puts self.join(",")
+          end
+        end)
+      end
+      def x(i)
+        [1, 2].include?(i)
+      end
+      x(3)
+      x(4)
+    RUBY
+
+    # Ensure raises happen correctly.
+    assert_in_out_err([], <<~RUBY, ["will raise", "int 1 not 3"])
+      class Integer
+        undef_method :==
+        def == x
+          raise "int \#{self} not \#{x}"
+        end
+      end
+      x = 3
+      puts "will raise"
+      begin
+        p [1, 2].include?(x)
+      rescue
+        puts $!
+      end
+    RUBY
+  end
+
+  def test_opt_newarray_send_include_p
+    [
+      'b = :b; [:a, b].include?(:b)',
+      # Use Object.new to ensure that we get newarray rather than duparray.
+      'value = 1; [Object.new, true, "true", 1].include?(value)',
+      'value = 1; [Object.new, "1"].include?(value.to_s)',
+      '[Object.new, "1"].include?(self) == false',
+    ].each do |code|
+      iseq = RubyVM::InstructionSequence.compile(code)
+      insn = iseq.disasm
+      assert_match(/opt_newarray_send/, insn)
+      assert_no_match(/\bnewarray\b/, insn)
+      assert_equal(true, eval(code))
+    end
+
+    x, y = :b, :c
+    assert_equal(true,  [:a, x].include?(x))
+    assert_equal(false, [:a, x].include?(y))
+
+    assert_in_out_err([], <<~RUBY, ["1,3", "3,3", "1,4", "4,4"])
+      class Array
+        prepend(Module.new do
+          def include?(i)
+            puts self.join(",")
+            # Modify self to prove that we are operating on a copy.
+            map! { i }
+            puts self.join(",")
+          end
+        end)
+      end
+      def x(i)
+        [1, i].include?(i)
+      end
+      x(3)
+      x(4)
+    RUBY
+
+    # Ensure raises happen correctly.
+    assert_in_out_err([], <<~RUBY, ["will raise", "int 1 not 3"])
+      class Integer
+        undef_method :==
+        def == x
+          raise "int \#{self} not \#{x}"
+        end
+      end
+      x = 3
+      puts "will raise"
+      begin
+        p [1, x].include?(x)
+      rescue
+        puts $!
+      end
+    RUBY
+  end
 end