require_relative '../spec_helper' require_relative '../fixtures/class' require_relative 'fixtures/metaclass' describe "self in a metaclass body (class << obj)" do it "is TrueClass for true" do class << true; self; end.should == TrueClass end it "is FalseClass for false" do class << false; self; end.should == FalseClass end it "is NilClass for nil" do class << nil; self; end.should == NilClass end it "raises a TypeError for numbers" do -> { class << 1; self; end }.should raise_error(TypeError) end it "raises a TypeError for symbols" do -> { class << :symbol; self; end }.should raise_error(TypeError) end it "is a singleton Class instance" do cls = class << mock('x'); self; end cls.is_a?(Class).should == true cls.should_not equal(Object) end end describe "A constant on a metaclass" do before :each do @object = Object.new class << @object CONST = self end end it "can be accessed after the metaclass body is reopened" do class << @object CONST.should == self end end it "can be accessed via self::CONST" do class << @object self::CONST.should == self end end it "can be accessed via const_get" do class << @object const_get(:CONST).should == self end end it "is not defined on the object's class" do @object.class.const_defined?(:CONST).should be_false end it "is not defined in the metaclass opener's scope" do class << @object CONST end -> { CONST }.should raise_error(NameError) end it "cannot be accessed via object::CONST" do -> do @object::CONST end.should raise_error(TypeError) end it "raises a NameError for anonymous_module::CONST" do @object = Class.new class << @object CONST = 100 end -> do @object::CONST end.should raise_error(NameError) end it "appears in the metaclass constant list" do constants = class << @object; constants; end constants.should include(:CONST) end it "does not appear in the object's class constant list" do @object.class.constants.should_not include(:CONST) end it "is not preserved when the object is duped" do @object = @object.dup -> do class << @object; CONST; end end.should raise_error(NameError) end it "is preserved when the object is cloned" do @object = @object.clone class << @object CONST.should_not be_nil end end end describe "calling methods on the metaclass" do it "calls a method on the metaclass" do MetaClassSpecs::A.cheese.should == 'edam' MetaClassSpecs::B.cheese.should == 'stilton' end it "calls a method on the instance's metaclass" do b = MetaClassSpecs::B.new b_meta = MetaClassSpecs.metaclass_of b b_meta.send(:define_method, :cheese) {'cheshire'} b.cheese.should == 'cheshire' end it "calls a method in deeper chains of metaclasses" do b = MetaClassSpecs::B.new b_meta = MetaClassSpecs.metaclass_of b b_meta_meta = MetaClassSpecs.metaclass_of b_meta b_meta_meta.send(:define_method, :cheese) {'gouda'} b_meta.cheese.should == 'gouda' b_meta_meta_meta = MetaClassSpecs.metaclass_of b_meta_meta b_meta_meta_meta.send(:define_method, :cheese) {'wensleydale'} b_meta_meta.cheese.should == 'wensleydale' end it "calls a method defined on the metaclass of the metaclass" do d_meta = MetaClassSpecs::D.singleton_class d_meta.ham.should == 'iberico' end end