Add specs for aliasing global variables

Author: eregon

spec/ruby/language/alias_spec.rb

@@ -244,3 +244,15 @@ def test_with_check(*args)
     }
   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