19 files changed, 272 insertions, 159 deletions

diff --git a/spec/ruby/core/struct/constants_spec.rb b/spec/ruby/core/struct/constants_spec.rb
index fa61a4b912..7e8af1a211 100644
--- a/spec/ruby/core/struct/constants_spec.rb
+++ b/spec/ruby/core/struct/constants_spec.rb
@@ -1,15 +1,13 @@
 require_relative '../../spec_helper'
 
-ruby_version_is "3.2" do
-  describe "Struct::Group" do
-    it "is no longer defined" do
-      Struct.should_not.const_defined?(:Group)
-    end
+describe "Struct::Group" do
+  it "is no longer defined" do
+    Struct.should_not.const_defined?(:Group)
   end
+end
 
-  describe "Struct::Passwd" do
-    it "is no longer defined" do
-      Struct.should_not.const_defined?(:Passwd)
-    end
+describe "Struct::Passwd" do
+  it "is no longer defined" do
+    Struct.should_not.const_defined?(:Passwd)
   end
 end
diff --git a/spec/ruby/core/struct/deconstruct_keys_spec.rb b/spec/ruby/core/struct/deconstruct_keys_spec.rb
index b4c84c49df..590e1ab40b 100644
--- a/spec/ruby/core/struct/deconstruct_keys_spec.rb
+++ b/spec/ruby/core/struct/deconstruct_keys_spec.rb
@@ -14,7 +14,7 @@ describe "Struct#deconstruct_keys" do
 
     -> {
       obj.deconstruct_keys
-    }.should raise_error(ArgumentError, /wrong number of arguments \(given 0, expected 1\)/)
+    }.should.raise(ArgumentError, /wrong number of arguments \(given 0, expected 1\)/)
   end
 
   it "returns only specified keys" do
@@ -40,6 +40,21 @@ describe "Struct#deconstruct_keys" do
     s.deconstruct_keys([0, 1, 2]).should == {0 => 10, 1 => 20, 2 => 30}
     s.deconstruct_keys([0, 1]   ).should == {0 => 10, 1 => 20}
     s.deconstruct_keys([0]      ).should == {0 => 10}
+    s.deconstruct_keys([-1]     ).should == {-1 => 30}
+  end
+
+  it "ignores incorrect position numbers" do
+    struct = Struct.new(:x, :y, :z)
+    s = struct.new(10, 20, 30)
+
+    s.deconstruct_keys([0, 3]).should == {0 => 10}
+  end
+
+  it "support mixing attribute names and argument position numbers" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    s.deconstruct_keys([0, :x]).should == {0 => 1, :x => 1}
   end
 
   it "returns an empty hash when there are more keys than attributes" do
@@ -57,6 +72,14 @@ describe "Struct#deconstruct_keys" do
     s.deconstruct_keys([:x, :a]).should == {x: 1}
   end
 
+  it "returns at first not existing argument position number" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    s.deconstruct_keys([3, 0]).should == {}
+    s.deconstruct_keys([0, 3]).should == {0 => 1}
+  end
+
   it "accepts nil argument and return all the attributes" do
     struct = Struct.new(:x, :y)
     obj = struct.new(1, 2)
@@ -64,13 +87,44 @@ describe "Struct#deconstruct_keys" do
     obj.deconstruct_keys(nil).should == {x: 1, y: 2}
   end
 
+  it "tries to convert a key with #to_int if index is not a String nor a Symbol, but responds to #to_int" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    key = mock("to_int")
+    key.should_receive(:to_int).and_return(1)
+
+    s.deconstruct_keys([key]).should == { key => 2 }
+  end
+
+  it "raises a TypeError if the conversion with #to_int does not return an Integer" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    key = mock("to_int")
+    key.should_receive(:to_int).and_return("not an Integer")
+
+    -> {
+      s.deconstruct_keys([key])
+    }.should raise_consistent_error(TypeError, /can't convert MockObject into Integer/)
+  end
+
+  it "raises TypeError if index is not a String, a Symbol and not convertible to Integer" do
+    struct = Struct.new(:x, :y)
+    s = struct.new(1, 2)
+
+    -> {
+      s.deconstruct_keys([0, []])
+    }.should.raise(TypeError, "no implicit conversion of Array into Integer")
+  end
+
   it "raise TypeError if passed anything except nil or array" do
     struct = Struct.new(:x, :y)
     s = struct.new(1, 2)
 
-    -> { s.deconstruct_keys('x') }.should raise_error(TypeError, /expected Array or nil/)
-    -> { s.deconstruct_keys(1)   }.should raise_error(TypeError, /expected Array or nil/)
-    -> { s.deconstruct_keys(:x)  }.should raise_error(TypeError, /expected Array or nil/)
-    -> { s.deconstruct_keys({})  }.should raise_error(TypeError, /expected Array or nil/)
+    -> { s.deconstruct_keys('x') }.should.raise(TypeError, /expected Array or nil/)
+    -> { s.deconstruct_keys(1)   }.should.raise(TypeError, /expected Array or nil/)
+    -> { s.deconstruct_keys(:x)  }.should.raise(TypeError, /expected Array or nil/)
+    -> { s.deconstruct_keys({})  }.should.raise(TypeError, /expected Array or nil/)
   end
 end
diff --git a/spec/ruby/core/struct/dig_spec.rb b/spec/ruby/core/struct/dig_spec.rb
index 93a52dbbe1..52e4d1dd9a 100644
--- a/spec/ruby/core/struct/dig_spec.rb
+++ b/spec/ruby/core/struct/dig_spec.rb
@@ -32,11 +32,11 @@ describe "Struct#dig" do
     instance = @klass.new(1)
     -> {
       instance.dig(:a, 3)
-    }.should raise_error(TypeError)
+    }.should.raise(TypeError)
   end
 
   it "raises an ArgumentError if no arguments provided" do
-    -> { @instance.dig }.should raise_error(ArgumentError)
+    -> { @instance.dig }.should.raise(ArgumentError)
   end
 
   it "calls #dig on any intermediate step with the rest of the sequence as arguments" do
diff --git a/spec/ruby/core/struct/each_pair_spec.rb b/spec/ruby/core/struct/each_pair_spec.rb
index 1230ca9026..db146c81e9 100644
--- a/spec/ruby/core/struct/each_pair_spec.rb
+++ b/spec/ruby/core/struct/each_pair_spec.rb
@@ -21,11 +21,11 @@ describe "Struct#each_pair" do
   end
 
   it "returns self if passed a block" do
-    @car.each_pair {}.should equal(@car)
+    @car.each_pair {}.should.equal?(@car)
   end
 
   it "returns an Enumerator if not passed a block" do
-    @car.each_pair.should be_an_instance_of(Enumerator)
+    @car.each_pair.should.instance_of?(Enumerator)
   end
 
   it_behaves_like :struct_accessor, :each_pair
diff --git a/spec/ruby/core/struct/each_spec.rb b/spec/ruby/core/struct/each_spec.rb
index 41c0fbd4d0..4fbdfee02a 100644
--- a/spec/ruby/core/struct/each_spec.rb
+++ b/spec/ruby/core/struct/each_spec.rb
@@ -19,7 +19,7 @@ describe "Struct#each" do
 
   it "returns an Enumerator if not passed a block" do
     car = StructClasses::Car.new('Ford', 'Ranger')
-    car.each.should be_an_instance_of(Enumerator)
+    car.each.should.instance_of?(Enumerator)
   end
 
   it_behaves_like :struct_accessor, :each
diff --git a/spec/ruby/core/struct/element_reference_spec.rb b/spec/ruby/core/struct/element_reference_spec.rb
index 0f6d547f66..b94f3aae8c 100644
--- a/spec/ruby/core/struct/element_reference_spec.rb
+++ b/spec/ruby/core/struct/element_reference_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Struct[]" do
   it "is a synonym for new" do
-    StructClasses::Ruby['2.0', 'i686'].should be_kind_of(StructClasses::Ruby)
+    StructClasses::Ruby['2.0', 'i686'].should.is_a?(StructClasses::Ruby)
   end
 end
 
@@ -26,20 +26,20 @@ describe "Struct#[]" do
 
   it "fails when it does not know about the requested attribute" do
     car = StructClasses::Car.new('Ford', 'Ranger')
-    -> { car[3]        }.should raise_error(IndexError)
-    -> { car[-4]       }.should raise_error(IndexError)
-    -> { car[:body]    }.should raise_error(NameError)
-    -> { car['wheels'] }.should raise_error(NameError)
+    -> { car[3]        }.should.raise(IndexError)
+    -> { car[-4]       }.should.raise(IndexError)
+    -> { car[:body]    }.should.raise(NameError)
+    -> { car['wheels'] }.should.raise(NameError)
   end
 
   it "fails if passed too many arguments" do
     car = StructClasses::Car.new('Ford', 'Ranger')
-    -> { car[:make, :model] }.should raise_error(ArgumentError)
+    -> { car[:make, :model] }.should.raise(ArgumentError)
   end
 
   it "fails if not passed a string, symbol, or integer" do
     car = StructClasses::Car.new('Ford', 'Ranger')
-    -> { car[Object.new] }.should raise_error(TypeError)
+    -> { car[Object.new] }.should.raise(TypeError)
   end
 
   it "returns attribute names that contain hyphens" do
diff --git a/spec/ruby/core/struct/element_set_spec.rb b/spec/ruby/core/struct/element_set_spec.rb
index 6ba7b081a9..e5438ca09a 100644
--- a/spec/ruby/core/struct/element_set_spec.rb
+++ b/spec/ruby/core/struct/element_set_spec.rb
@@ -21,9 +21,16 @@ describe "Struct#[]=" do
   it "fails when trying to assign attributes which don't exist" do
     car = StructClasses::Car.new('Ford', 'Ranger')
 
-    -> { car[:something] = true }.should raise_error(NameError)
-    -> { car[3] = true          }.should raise_error(IndexError)
-    -> { car[-4] = true         }.should raise_error(IndexError)
-    -> { car[Object.new] = true }.should raise_error(TypeError)
+    -> { car[:something] = true }.should.raise(NameError)
+    -> { car[3] = true          }.should.raise(IndexError)
+    -> { car[-4] = true         }.should.raise(IndexError)
+    -> { car[Object.new] = true }.should.raise(TypeError)
+  end
+
+  it "raises a FrozenError on a frozen struct" do
+    car = StructClasses::Car.new('Ford', 'Ranger')
+    car.freeze
+
+    -> { car[:model] = 'Escape' }.should.raise(FrozenError)
   end
 end
diff --git a/spec/ruby/core/struct/eql_spec.rb b/spec/ruby/core/struct/eql_spec.rb
index c864b2b943..327c927278 100644
--- a/spec/ruby/core/struct/eql_spec.rb
+++ b/spec/ruby/core/struct/eql_spec.rb
@@ -8,6 +8,6 @@ describe "Struct#eql?" do
   it "returns false if any corresponding elements are not #eql?" do
     car = StructClasses::Car.new("Honda", "Accord", 1998)
     similar_car = StructClasses::Car.new("Honda", "Accord", 1998.0)
-    car.should_not eql(similar_car)
+    car.should_not.eql?(similar_car)
   end
 end
diff --git a/spec/ruby/core/struct/fixtures/classes.rb b/spec/ruby/core/struct/fixtures/classes.rb
index bf838d05df..675d403abd 100644
--- a/spec/ruby/core/struct/fixtures/classes.rb
+++ b/spec/ruby/core/struct/fixtures/classes.rb
@@ -3,6 +3,7 @@ module StructClasses
   class Apple < Struct; end
 
   Ruby = Struct.new(:version, :platform)
+  Single = Struct.new(:value)
 
   Car = Struct.new(:make, :model, :year)
 
@@ -29,4 +30,6 @@ module StructClasses
       super
     end
   end
+
+  class StructSubclass < Struct; end
 end
diff --git a/spec/ruby/core/struct/hash_spec.rb b/spec/ruby/core/struct/hash_spec.rb
index 53361eb7a9..750387b326 100644
--- a/spec/ruby/core/struct/hash_spec.rb
+++ b/spec/ruby/core/struct/hash_spec.rb
@@ -8,14 +8,14 @@ describe "Struct#hash" do
     [StructClasses::Ruby.new("1.8.6", "PPC"),
      StructClasses::Car.new("Hugo", "Foo", "1972")].each do |stc|
       stc.hash.should == stc.dup.hash
-      stc.hash.should be_kind_of(Integer)
+      stc.hash.should.is_a?(Integer)
     end
   end
 
   it "returns the same value if structs are #eql?" do
     car = StructClasses::Car.new("Honda", "Accord", "1998")
     similar_car = StructClasses::Car.new("Honda", "Accord", "1998")
-    car.should eql(similar_car)
+    car.should.eql?(similar_car)
     car.hash.should == similar_car.hash
   end
 
diff --git a/spec/ruby/core/struct/initialize_spec.rb b/spec/ruby/core/struct/initialize_spec.rb
index a5ebe9551c..c824f52e13 100644
--- a/spec/ruby/core/struct/initialize_spec.rb
+++ b/spec/ruby/core/struct/initialize_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 describe "Struct#initialize" do
 
   it "is private" do
-    StructClasses::Car.should have_private_instance_method(:initialize)
+    StructClasses::Car.private_instance_methods(true).should.include?(:initialize)
   end
 
   it 'allows valid Ruby method names for members' do
@@ -41,21 +41,34 @@ describe "Struct#initialize" do
     StructClasses::SubclassX.new(:y).new.key.should == :value
   end
 
-  ruby_version_is "3.1"..."3.2" do
-    it "warns about passing only keyword arguments" do
-      -> {
-        StructClasses::Ruby.new(version: "3.1", platform: "OS")
-      }.should complain(/warning: Passing only keyword arguments/)
-    end
+  it "can be initialized with keyword arguments" do
+    positional_args = StructClasses::Ruby.new("3.2", "OS")
+    keyword_args = StructClasses::Ruby.new(version: "3.2", platform: "OS")
+
+    positional_args.version.should == keyword_args.version
+    positional_args.platform.should == keyword_args.platform
   end
 
-  ruby_version_is "3.2" do
-    it "can be initialized with keyword arguments" do
-      positional_args = StructClasses::Ruby.new("3.2", "OS")
-      keyword_args = StructClasses::Ruby.new(version: "3.2", platform: "OS")
+  it "accepts positional arguments with empty keyword arguments" do
+    data = StructClasses::Single.new(42, **{})
+
+    data.value.should == 42
+
+    data = StructClasses::Ruby.new("3.2", "OS", **{})
 
-      positional_args.version.should == keyword_args.version
-      positional_args.platform.should == keyword_args.platform
+    data.version.should == "3.2"
+    data.platform.should == "OS"
+  end
+
+  it "can be called via delegated ... from a prepended module" do
+    wrapper = Module.new do
+      def initialize(...)
+        super(...)
+      end
     end
+
+    klass = Class.new(Struct.new(:a)) { prepend wrapper }
+    s = klass.new("x")
+    s.a.should == "x"
   end
 end
diff --git a/spec/ruby/core/struct/instance_variable_get_spec.rb b/spec/ruby/core/struct/instance_variable_get_spec.rb
index e4a3ea87dc..e3555cd246 100644
--- a/spec/ruby/core/struct/instance_variable_get_spec.rb
+++ b/spec/ruby/core/struct/instance_variable_get_spec.rb
@@ -4,7 +4,7 @@ require_relative 'fixtures/classes'
 describe "Struct#instance_variable_get" do
   it "returns nil for attributes" do
     car = StructClasses::Car.new("Hugo", "Foo", "1972")
-    car.instance_variable_get(:@make).should be_nil
+    car.instance_variable_get(:@make).should == nil
   end
 
   it "returns a user value for variables with the same name as attributes" do
diff --git a/spec/ruby/core/struct/keyword_init_spec.rb b/spec/ruby/core/struct/keyword_init_spec.rb
index 8de4c14351..42fcd3cc29 100644
--- a/spec/ruby/core/struct/keyword_init_spec.rb
+++ b/spec/ruby/core/struct/keyword_init_spec.rb
@@ -1,40 +1,45 @@
 require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
 
-ruby_version_is "3.1" do
-  # See https://bugs.ruby-lang.org/issues/18008
-  describe "StructClass#keyword_init?" do
-    it "returns true for a struct that accepts keyword arguments to initialize" do
-      struct = Struct.new(:arg, keyword_init: true)
-      struct.keyword_init?.should be_true
-    end
+# See https://bugs.ruby-lang.org/issues/18008
+describe "StructClass#keyword_init?" do
+  it "returns true for a struct that accepts keyword arguments to initialize" do
+    struct = Struct.new(:arg, keyword_init: true)
+    struct.keyword_init?.should == true
+  end
 
-    it "returns false for a struct that does not accept keyword arguments to initialize" do
-      struct = Struct.new(:arg, keyword_init: false)
-      struct.keyword_init?.should be_false
-    end
+  it "returns false for a struct that does not accept keyword arguments to initialize" do
+    struct = Struct.new(:arg, keyword_init: false)
+    struct.keyword_init?.should == false
+  end
 
-    it "returns nil for a struct that did not explicitly specify keyword_init" do
-      struct = Struct.new(:arg)
-      struct.keyword_init?.should be_nil
-    end
+  it "returns nil for a struct that did not explicitly specify keyword_init" do
+    struct = Struct.new(:arg)
+    struct.keyword_init?.should == nil
+  end
 
-    it "returns nil for a struct that does specify keyword_init to be nil" do
-      struct = Struct.new(:arg, keyword_init: nil)
-      struct.keyword_init?.should be_nil
-    end
+  it "returns nil for a struct that does specify keyword_init to be nil" do
+    struct = Struct.new(:arg, keyword_init: nil)
+    struct.keyword_init?.should == nil
+  end
 
-    it "returns true for any truthy value, not just for true" do
-      struct = Struct.new(:arg, keyword_init: 1)
-      struct.keyword_init?.should be_true
+  it "returns true for any truthy value, not just for true" do
+    struct = Struct.new(:arg, keyword_init: 1)
+    struct.keyword_init?.should == true
 
-      struct = Struct.new(:arg, keyword_init: "")
-      struct.keyword_init?.should be_true
+    struct = Struct.new(:arg, keyword_init: "")
+    struct.keyword_init?.should == true
 
-      struct = Struct.new(:arg, keyword_init: [])
-      struct.keyword_init?.should be_true
+    struct = Struct.new(:arg, keyword_init: [])
+    struct.keyword_init?.should == true
+
+    struct = Struct.new(:arg, keyword_init: {})
+    struct.keyword_init?.should == true
+  end
 
-      struct = Struct.new(:arg, keyword_init: {})
-      struct.keyword_init?.should be_true
+  context "class inheriting Struct" do
+    it "isn't available in a subclass" do
+      StructClasses::StructSubclass.should_not.respond_to?(:keyword_init?)
     end
   end
 end
diff --git a/spec/ruby/core/struct/members_spec.rb b/spec/ruby/core/struct/members_spec.rb
index 1f2ff950d9..1ff7b9387a 100644
--- a/spec/ruby/core/struct/members_spec.rb
+++ b/spec/ruby/core/struct/members_spec.rb
@@ -11,3 +11,15 @@ describe "Struct#members" do
 
   it_behaves_like :struct_accessor, :members
 end
+
+describe "StructClass#members" do
+  it "returns an array of attribute names" do
+    StructClasses::Car.members.should == [:make, :model, :year]
+  end
+
+  context "class inheriting Struct" do
+    it "isn't available in a subclass" do
+      StructClasses::StructSubclass.should_not.respond_to?(:members)
+    end
+  end
+end
diff --git a/spec/ruby/core/struct/new_spec.rb b/spec/ruby/core/struct/new_spec.rb
index 8758051a81..b3ece2efed 100644
--- a/spec/ruby/core/struct/new_spec.rb
+++ b/spec/ruby/core/struct/new_spec.rb
@@ -6,6 +6,8 @@ describe "Struct.new" do
     struct = Struct.new('Animal', :name, :legs, :eyeballs)
     struct.should == Struct::Animal
     struct.name.should == "Struct::Animal"
+  ensure
+    Struct.send(:remove_const, :Animal)
   end
 
   it "overwrites previously defined constants with string as first argument" do
@@ -19,6 +21,8 @@ describe "Struct.new" do
     second.should == Struct::Person
 
     first.members.should_not == second.members
+  ensure
+    Struct.send(:remove_const, :Person)
   end
 
   it "calls to_str on its first argument (constant name)" do
@@ -27,89 +31,71 @@ describe "Struct.new" do
     struct = Struct.new(obj)
     struct.should == Struct::Foo
     struct.name.should == "Struct::Foo"
+  ensure
+    Struct.send(:remove_const, :Foo)
   end
 
   it "creates a new anonymous class with nil first argument" do
     struct = Struct.new(nil, :foo)
     struct.new("bar").foo.should == "bar"
-    struct.should be_kind_of(Class)
-    struct.name.should be_nil
+    struct.should.is_a?(Class)
+    struct.name.should == nil
   end
 
   it "creates a new anonymous class with symbol arguments" do
     struct = Struct.new(:make, :model)
-    struct.should be_kind_of(Class)
+    struct.should.is_a?(Class)
     struct.name.should == nil
   end
 
   it "does not create a constant with symbol as first argument" do
     Struct.new(:Animal2, :name, :legs, :eyeballs)
-    Struct.const_defined?("Animal2").should be_false
+    Struct.const_defined?("Animal2").should == false
   end
 
   it "allows non-ASCII member name" do
-    name = "r\xe9sum\xe9".force_encoding(Encoding::ISO_8859_1).to_sym
+    name = "r\xe9sum\xe9".dup.force_encoding(Encoding::ISO_8859_1).to_sym
     struct = Struct.new(name)
     struct.new("foo").send(name).should == "foo"
   end
 
   it "fails with invalid constant name as first argument" do
-    -> { Struct.new('animal', :name, :legs, :eyeballs) }.should raise_error(NameError)
+    -> { Struct.new('animal', :name, :legs, :eyeballs) }.should.raise(NameError)
   end
 
   it "raises a TypeError if object doesn't respond to to_sym" do
-    -> { Struct.new(:animal, mock('giraffe'))      }.should raise_error(TypeError)
-    -> { Struct.new(:animal, 1.0)                  }.should raise_error(TypeError)
-    -> { Struct.new(:animal, Time.now)             }.should raise_error(TypeError)
-    -> { Struct.new(:animal, Class)                }.should raise_error(TypeError)
-    -> { Struct.new(:animal, nil)                  }.should raise_error(TypeError)
-    -> { Struct.new(:animal, true)                 }.should raise_error(TypeError)
-    -> { Struct.new(:animal, ['chris', 'evan'])    }.should raise_error(TypeError)
-  end
-
-  ruby_version_is ""..."3.2" do
-    it "raises a TypeError or ArgumentError if passed a Hash with an unknown key" do
-      # CRuby < 3.2 raises ArgumentError: unknown keyword: :name, but that seems a bug:
-      # https://bugs.ruby-lang.org/issues/18632
-      -> { Struct.new(:animal, { name: 'chris' }) }.should raise_error(StandardError) { |e|
-        [ArgumentError, TypeError].should.include?(e.class)
-      }
-    end
-  end
-
-  ruby_version_is "3.2" do
-    it "raises a TypeError if passed a Hash with an unknown key" do
-      -> { Struct.new(:animal, { name: 'chris' }) }.should raise_error(TypeError)
-    end
+    -> { Struct.new(:animal, mock('giraffe'))      }.should.raise(TypeError)
+    -> { Struct.new(:animal, 1.0)                  }.should.raise(TypeError)
+    -> { Struct.new(:animal, Time.now)             }.should.raise(TypeError)
+    -> { Struct.new(:animal, Class)                }.should.raise(TypeError)
+    -> { Struct.new(:animal, nil)                  }.should.raise(TypeError)
+    -> { Struct.new(:animal, true)                 }.should.raise(TypeError)
+    -> { Struct.new(:animal, ['chris', 'evan'])    }.should.raise(TypeError)
   end
 
-  ruby_version_is ""..."3.3" do
-    it "raises ArgumentError if not provided any arguments" do
-      -> { Struct.new }.should raise_error(ArgumentError)
-    end
+  it "raises a TypeError if passed a Hash with an unknown key" do
+    -> { Struct.new(:animal, { name: 'chris' }) }.should.raise(TypeError)
   end
 
-  ruby_version_is "3.3" do
-    it "works when not provided any arguments" do
-      c = Struct.new
-      c.should be_kind_of(Class)
-      c.superclass.should == Struct
-    end
+  it "works when not provided any arguments" do
+    c = Struct.new
+    c.should.is_a?(Class)
+    c.superclass.should == Struct
   end
 
   it "raises ArgumentError when there is a duplicate member" do
-    -> { Struct.new(:foo, :foo) }.should raise_error(ArgumentError, "duplicate member: foo")
+    -> { Struct.new(:foo, :foo) }.should.raise(ArgumentError, "duplicate member: foo")
   end
 
   it "raises a TypeError if object is not a Symbol" do
     obj = mock(':ruby')
     def obj.to_sym() :ruby end
-    -> { Struct.new(:animal, obj) }.should raise_error(TypeError)
+    -> { Struct.new(:animal, obj) }.should.raise(TypeError)
   end
 
   it "processes passed block with instance_eval" do
     klass = Struct.new(:something) { @something_else = 'something else entirely!' }
-    klass.instance_variables.should include(:@something_else)
+    klass.instance_variables.should.include?(:@something_else)
   end
 
   context "with a block" do
@@ -130,7 +116,7 @@ describe "Struct.new" do
       klass = Struct.new(:attr) do |block_parameter|
         given = block_parameter
       end
-      klass.should equal(given)
+      klass.should.equal?(given)
     end
   end
 
@@ -138,6 +124,8 @@ describe "Struct.new" do
     it "creates a constant in subclass' namespace" do
       struct = StructClasses::Apple.new('Computer', :size)
       struct.should == StructClasses::Apple::Computer
+    ensure
+      StructClasses::Apple.send(:remove_const, :Computer)
     end
 
     it "creates an instance" do
@@ -145,42 +133,56 @@ describe "Struct.new" do
     end
 
     it "creates reader methods" do
-      StructClasses::Ruby.new.should have_method(:version)
-      StructClasses::Ruby.new.should have_method(:platform)
+      StructClasses::Ruby.new.should.respond_to?(:version)
+      StructClasses::Ruby.new.should.respond_to?(:platform)
     end
 
     it "creates writer methods" do
-      StructClasses::Ruby.new.should have_method(:version=)
-      StructClasses::Ruby.new.should have_method(:platform=)
+      StructClasses::Ruby.new.should.respond_to?(:version=)
+      StructClasses::Ruby.new.should.respond_to?(:platform=)
     end
 
     it "fails with too many arguments" do
-      -> { StructClasses::Ruby.new('2.0', 'i686', true) }.should raise_error(ArgumentError)
+      -> { StructClasses::Ruby.new('2.0', 'i686', true) }.should.raise(ArgumentError)
     end
 
-    ruby_version_is ''...'3.1' do
-      it "passes a hash as a normal argument" do
-        type = Struct.new(:args)
+    it "accepts keyword arguments to initialize" do
+      type = Struct.new(:args)
 
-        obj = suppress_warning {type.new(keyword: :arg)}
-        obj2 = type.new(*[{keyword: :arg}])
+      obj = type.new(args: 42)
+      obj2 = type.new(42)
 
-        obj.should == obj2
-        obj.args.should == {keyword: :arg}
-        obj2.args.should == {keyword: :arg}
-      end
+      obj.should == obj2
+      obj.args.should == 42
+      obj2.args.should == 42
     end
 
-    ruby_version_is '3.2' do
-      it "accepts keyword arguments to initialize" do
-        type = Struct.new(:args)
+    context "given positional and keyword arguments" do
+      it "treats keyword arguments as a positional parameter" do
+        type = Struct.new(:a, :b)
+        s = type.new("a", b: "b")
+        s.a.should == "a"
+        s.b.should == {b: "b"}
+
+        type = Struct.new(:a, :b, :c)
+        s = type.new("a", b: "b", c: "c")
+        s.a.should == "a"
+        s.b.should == {b: "b", c: "c"}
+        s.c.should == nil
+      end
+
+      it "ignores empty keyword arguments" do
+        type = Struct.new(:a, :b)
+        h = {}
+        s = type.new("a", **h)
 
-        obj = type.new(args: 42)
-        obj2 = type.new(42)
+        s.a.should == "a"
+        s.b.should == nil
+      end
 
-        obj.should == obj2
-        obj.args.should == 42
-        obj2.args.should == 42
+      it "raises ArgumentError when all struct attribute values are specified" do
+        type = Struct.new(:a, :b)
+        -> { type.new("a", "b", c: "c") }.should.raise(ArgumentError, "struct size differs")
       end
     end
   end
@@ -197,7 +199,7 @@ describe "Struct.new" do
     end
 
     it "raises when there is a duplicate member" do
-      -> { Struct.new(:foo, :foo, keyword_init: true) }.should raise_error(ArgumentError, "duplicate member: foo")
+      -> { Struct.new(:foo, :foo, keyword_init: true) }.should.raise(ArgumentError, "duplicate member: foo")
     end
 
     describe "new class instantiation" do
@@ -210,31 +212,31 @@ describe "Struct.new" do
       it "allows missing arguments" do
         obj = @struct_with_kwa.new(name: "elefant")
         obj.name.should == "elefant"
-        obj.legs.should be_nil
+        obj.legs.should == nil
       end
 
       it "allows no arguments" do
         obj = @struct_with_kwa.new
-        obj.name.should be_nil
-        obj.legs.should be_nil
+        obj.name.should == nil
+        obj.legs.should == nil
       end
 
       it "raises ArgumentError when passed not declared keyword argument" do
         -> {
           @struct_with_kwa.new(name: "elefant", legs: 4, foo: "bar")
-        }.should raise_error(ArgumentError, /unknown keywords: foo/)
+        }.should.raise(ArgumentError, /unknown keywords: foo/)
       end
 
       it "raises ArgumentError when passed a list of arguments" do
         -> {
           @struct_with_kwa.new("elefant", 4)
-        }.should raise_error(ArgumentError, /wrong number of arguments/)
+        }.should.raise(ArgumentError, /wrong number of arguments/)
       end
 
       it "raises ArgumentError when passed a single non-hash argument" do
         -> {
           @struct_with_kwa.new("elefant")
-        }.should raise_error(ArgumentError, /wrong number of arguments/)
+        }.should.raise(ArgumentError, /wrong number of arguments/)
       end
     end
   end
diff --git a/spec/ruby/core/struct/shared/select.rb b/spec/ruby/core/struct/shared/select.rb
index 35abee461b..dfa1a809fe 100644
--- a/spec/ruby/core/struct/shared/select.rb
+++ b/spec/ruby/core/struct/shared/select.rb
@@ -4,7 +4,7 @@ require_relative '../fixtures/classes'
 describe :struct_select, shared: true do
   it "raises an ArgumentError if given any non-block arguments" do
     struct = StructClasses::Car.new
-    -> { struct.send(@method, 1) { } }.should raise_error(ArgumentError)
+    -> { struct.send(@method, 1) { } }.should.raise(ArgumentError)
   end
 
   it "returns a new array of elements for which block is true" do
@@ -14,13 +14,13 @@ describe :struct_select, shared: true do
 
   it "returns an instance of Array" do
     struct = StructClasses::Car.new("Ford", "Escort", "1995")
-    struct.send(@method) { true }.should be_an_instance_of(Array)
+    struct.send(@method) { true }.should.instance_of?(Array)
   end
 
   describe "without block" do
     it "returns an instance of Enumerator" do
       struct = Struct.new(:foo).new
-      struct.send(@method).should be_an_instance_of(Enumerator)
+      struct.send(@method).should.instance_of?(Enumerator)
     end
   end
 end
diff --git a/spec/ruby/core/struct/struct_spec.rb b/spec/ruby/core/struct/struct_spec.rb
index 8817dc1a58..9fab9c0629 100644
--- a/spec/ruby/core/struct/struct_spec.rb
+++ b/spec/ruby/core/struct/struct_spec.rb
@@ -21,7 +21,7 @@ describe "Struct anonymous class instance methods" do
 
   it "reader method should not interfere with undefined methods" do
     car = StructClasses::Car.new('Ford', 'Ranger')
-    -> { car.something_weird }.should raise_error(NoMethodError)
+    -> { car.something_weird }.should.raise(NoMethodError)
   end
 
   it "writer method be a synonym for []=" do
@@ -33,6 +33,13 @@ describe "Struct anonymous class instance methods" do
     car['model'].should == 'F150'
     car[1].should == 'F150'
   end
+
+  it "writer methods raise a FrozenError on a frozen struct" do
+    car = StructClasses::Car.new('Ford', 'Ranger')
+    car.freeze
+
+    -> { car.model = 'Escape' }.should.raise(FrozenError)
+  end
 end
 
 describe "Struct subclasses" do
diff --git a/spec/ruby/core/struct/to_h_spec.rb b/spec/ruby/core/struct/to_h_spec.rb
index bfb0af07ba..e0846ef268 100644
--- a/spec/ruby/core/struct/to_h_spec.rb
+++ b/spec/ruby/core/struct/to_h_spec.rb
@@ -21,20 +21,32 @@ describe "Struct#to_h" do
       h.should == { "make" => "ford", "model" => "ranger", "year" => "" }
     end
 
+    it "passes to a block each pair's key and value as separate arguments" do
+      s = StructClasses::Ruby.new('3.2.4', 'macos')
+
+      ScratchPad.record []
+      s.to_h { |k, v| ScratchPad << [k, v]; [k, v] }
+      ScratchPad.recorded.sort.should == [[:platform, 'macos'], [:version, '3.2.4']]
+
+      ScratchPad.record []
+      s.to_h { |*args| ScratchPad << args; [args[0], args[1]] }
+      ScratchPad.recorded.sort.should == [[:platform, 'macos'], [:version, '3.2.4']]
+    end
+
     it "raises ArgumentError if block returns longer or shorter array" do
       -> do
         StructClasses::Car.new.to_h { |k, v| [k.to_s, "#{v}".downcase, 1] }
-      end.should raise_error(ArgumentError, /element has wrong array length/)
+      end.should.raise(ArgumentError, /element has wrong array length/)
 
       -> do
         StructClasses::Car.new.to_h { |k, v| [k] }
-      end.should raise_error(ArgumentError, /element has wrong array length/)
+      end.should.raise(ArgumentError, /element has wrong array length/)
     end
 
     it "raises TypeError if block returns something other than Array" do
       -> do
         StructClasses::Car.new.to_h { |k, v| "not-array" }
-      end.should raise_error(TypeError, /wrong element type String/)
+      end.should.raise(TypeError, /wrong element type String/)
     end
 
     it "coerces returned pair to Array with #to_ary" do
@@ -50,7 +62,7 @@ describe "Struct#to_h" do
 
       -> do
         StructClasses::Car.new.to_h { |k| x }
-      end.should raise_error(TypeError, /wrong element type MockObject/)
+      end.should.raise(TypeError, /wrong element type MockObject/)
     end
   end
 end
diff --git a/spec/ruby/core/struct/values_at_spec.rb b/spec/ruby/core/struct/values_at_spec.rb
index 5e5a496600..6aac5d96b3 100644
--- a/spec/ruby/core/struct/values_at_spec.rb
+++ b/spec/ruby/core/struct/values_at_spec.rb
@@ -14,8 +14,8 @@ describe "Struct#values_at" do
     end
 
     it "raises IndexError if any of integers is out of range" do
-      -> { @movie.values_at(3) }.should raise_error(IndexError, "offset 3 too large for struct(size:3)")
-      -> { @movie.values_at(-4) }.should raise_error(IndexError, "offset -4 too small for struct(size:3)")
+      -> { @movie.values_at(3) }.should.raise(IndexError, "offset 3 too large for struct(size:3)")
+      -> { @movie.values_at(-4) }.should.raise(IndexError, "offset -4 too small for struct(size:3)")
     end
   end
 
@@ -29,7 +29,7 @@ describe "Struct#values_at" do
     end
 
     it "raises RangeError if any element of the range is negative and out of range" do
-      -> { @movie.values_at(-4..3) }.should raise_error(RangeError, "-4..3 out of range")
+      -> { @movie.values_at(-4..3) }.should.raise(RangeError, "-4..3 out of range")
     end
 
     it "supports endless Range" do
@@ -54,6 +54,6 @@ describe "Struct#values_at" do
   end
 
   it "fails when passed unsupported types" do
-    -> { @movie.values_at('make') }.should raise_error(TypeError, "no implicit conversion of String into Integer")
+    -> { @movie.values_at('make') }.should.raise(TypeError, "no implicit conversion of String into Integer")
   end
 end