1 files changed, 190 insertions, 0 deletions
diff --git a/spec/rubyspec/language/alias_spec.rb b/spec/rubyspec/language/alias_spec.rb
new file mode 100644
index 0000000000..626e37a603
--- /dev/null
+++ b/spec/rubyspec/language/alias_spec.rb
@@ -0,0 +1,190 @@
+require File.expand_path('../../spec_helper', __FILE__)
+
+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 "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
+    lambda { 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
+    lambda { 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
+    lambda { 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
+    class Sub < AliasObject;end
+    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
+    Sub.new.test("testing").should == 4
+  end
+
+  it "is not allowed against Fixnum or String instances" do
+    lambda do
+      1.instance_eval do
+        alias :foo :to_s
+      end
+    end.should raise_error(TypeError)
+
+    lambda 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
+    lambda { @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