require_relative '../spec_helper' class AliasObject attr :foo attr_reader :bar attr_accessor :baz def prep; @foo = 3; @bar = 4; end def value; 5; end def false_value; 6; end def self.klass_method; 7; end end describe "The alias keyword" do before :each do @obj = AliasObject.new @meta = class << @obj;self;end end it "creates a new name for an existing method" do @meta.class_eval do alias __value value end @obj.__value.should == 5 end it "works with a simple symbol on the left-hand side" do @meta.class_eval do alias :a value end @obj.a.should == 5 end it "works with a single quoted symbol on the left-hand side" do @meta.class_eval do alias :'a' value end @obj.a.should == 5 end it "works with a double quoted symbol on the left-hand side" do @meta.class_eval do alias :"a" value end @obj.a.should == 5 end it "works with an interpolated symbol on the left-hand side" do @meta.class_eval do alias :"#{'a'}" value end @obj.a.should == 5 end it "works with a simple symbol on the right-hand side" do @meta.class_eval do alias a :value end @obj.a.should == 5 end it "works with a single quoted symbol on the right-hand side" do @meta.class_eval do alias a :'value' end @obj.a.should == 5 end it "works with a double quoted symbol on the right-hand side" do @meta.class_eval do alias a :"value" end @obj.a.should == 5 end it "works with an interpolated symbol on the right-hand side" do @meta.class_eval do alias a :"#{'value'}" end @obj.a.should == 5 end it "adds the new method to the list of methods" do original_methods = @obj.methods @meta.class_eval do alias __value value end (@obj.methods - original_methods).map {|m| m.to_s }.should == ["__value"] end it "adds the new method to the list of public methods" do original_methods = @obj.public_methods @meta.class_eval do alias __value value end (@obj.public_methods - original_methods).map {|m| m.to_s }.should == ["__value"] end it "overwrites an existing method with the target name" do @meta.class_eval do alias false_value value end @obj.false_value.should == 5 end it "is reversible" do @meta.class_eval do alias __value value alias value false_value end @obj.value.should == 6 @meta.class_eval do alias value __value end @obj.value.should == 5 end it "operates on the object's metaclass when used in instance_eval" do @obj.instance_eval do alias __value value end @obj.__value.should == 5 -> { AliasObject.new.__value }.should raise_error(NoMethodError) end it "operates on the class/module metaclass when used in instance_eval" do AliasObject.instance_eval do alias __klass_method klass_method end AliasObject.__klass_method.should == 7 -> { Object.__klass_method }.should raise_error(NoMethodError) end it "operates on the class/module metaclass when used in instance_exec" do AliasObject.instance_exec do alias __klass_method2 klass_method end AliasObject.__klass_method2.should == 7 -> { Object.__klass_method2 }.should raise_error(NoMethodError) end it "operates on methods defined via attr, attr_reader, and attr_accessor" do @obj.prep @obj.instance_eval do alias afoo foo alias abar bar alias abaz baz end @obj.afoo.should == 3 @obj.abar.should == 4 @obj.baz = 5 @obj.abaz.should == 5 end it "operates on methods with splat arguments" do class AliasObject2;end AliasObject2.class_eval do def test(*args) 4 end def test_with_check(*args) test_without_check(*args) end alias test_without_check test alias test test_with_check end AliasObject2.new.test(1,2,3,4,5).should == 4 end it "operates on methods with splat arguments on eigenclasses" do @meta.class_eval do def test(*args) 4 end def test_with_check(*args) test_without_check(*args) end alias test_without_check test alias test test_with_check end @obj.test(1,2,3,4,5).should == 4 end it "operates on methods with splat arguments defined in a superclass" do alias_class = Class.new alias_class.class_eval do def test(*args) 4 end def test_with_check(*args) test_without_check(*args) end end sub = Class.new(alias_class) do alias test_without_check test alias test test_with_check end sub.new.test(1,2,3,4,5).should == 4 end it "operates on methods with splat arguments defined in a superclass using text block for class eval" do subclass = Class.new(AliasObject) AliasObject.class_eval <<-code def test(*args) 4 end def test_with_check(*args) test_without_check(*args) end alias test_without_check test alias test test_with_check code subclass.new.test("testing").should == 4 end it "is not allowed against Fixnum or String instances" do -> do 1.instance_eval do alias :foo :to_s end end.should raise_error(TypeError) -> do :blah.instance_eval do alias :foo :to_s end end.should raise_error(TypeError) end it "on top level defines the alias on Object" do # because it defines on the default definee / current module ruby_exe("def foo; end; alias bla foo; print method(:bla).owner", escape: true).should == "Object" end it "raises a NameError when passed a missing name" do -> { @meta.class_eval { alias undef_method not_exist } }.should raise_error(NameError) { |e| # a NameError and not a NoMethodError e.class.should == NameError } end end describe "The alias keyword" do it "can create a new global variable, synonym of the original" do code = '$a = 1; alias $b $a; p [$a, $b]; $b = 2; p [$a, $b]' ruby_exe(code).should == "[1, 1]\n[2, 2]\n" end it "can override an existing global variable and make them synonyms" do code = '$a = 1; $b = 2; alias $b $a; p [$a, $b]; $b = 3; p [$a, $b]' ruby_exe(code).should == "[1, 1]\n[3, 3]\n" end end