5 files changed, 54 insertions, 12 deletions
diff --git a/lib/puppet/parser/ast/leaf.rb b/lib/puppet/parser/ast/leaf.rb
index 07bba1b4c..b583149b3 100644
--- a/lib/puppet/parser/ast/leaf.rb
+++ b/lib/puppet/parser/ast/leaf.rb
@@ -16,6 +16,8 @@ class Puppet::Parser::AST
             if ! options[:sensitive] && obj.respond_to?(:downcase)
                 obj = obj.downcase
             end
+            # "" == undef for case/selector/if
+            return true if obj == "" and value == :undef
             obj == value
         end
 
@@ -125,7 +127,10 @@ class Puppet::Parser::AST
         # not include syntactical constructs, like '$' and '{}').
         def evaluate(scope)
             parsewrap do
-                return scope.lookupvar(@value)
+                if (var = scope.lookupvar(@value, false)) == :undefined
+                    var = :undef
+                end
+                var
             end
         end
 
diff --git a/spec/unit/parser/ast/arithmetic_operator.rb b/spec/unit/parser/ast/arithmetic_operator.rb
index 4a0be483b..ad8d9947b 100755
--- a/spec/unit/parser/ast/arithmetic_operator.rb
+++ b/spec/unit/parser/ast/arithmetic_operator.rb
@@ -61,8 +61,8 @@ describe Puppet::Parser::AST::ArithmeticOperator do
     end
 
     it "should work for variables too" do
-        @scope.expects(:lookupvar).with("one").returns(1)
-        @scope.expects(:lookupvar).with("two").returns(2)
+        @scope.expects(:lookupvar).with("one", false).returns(1)
+        @scope.expects(:lookupvar).with("two", false).returns(2)
         one = ast::Variable.new( :value => "one" )
         two = ast::Variable.new( :value => "two" )
 
diff --git a/spec/unit/parser/ast/comparison_operator.rb b/spec/unit/parser/ast/comparison_operator.rb
index 26311797f..97402433f 100755
--- a/spec/unit/parser/ast/comparison_operator.rb
+++ b/spec/unit/parser/ast/comparison_operator.rb
@@ -71,8 +71,8 @@ describe Puppet::Parser::AST::ComparisonOperator do
         one = Puppet::Parser::AST::Variable.new( :value => "one" )
         two = Puppet::Parser::AST::Variable.new( :value => "two" )
 
-        @scope.expects(:lookupvar).with("one").returns(1)
-        @scope.expects(:lookupvar).with("two").returns(2)
+        @scope.expects(:lookupvar).with("one", false).returns(1)
+        @scope.expects(:lookupvar).with("two", false).returns(2)
 
         operator = Puppet::Parser::AST::ComparisonOperator.new :lval => one, :operator => "<", :rval => two
         operator.evaluate(@scope).should == true
diff --git a/spec/unit/parser/ast/leaf.rb b/spec/unit/parser/ast/leaf.rb
index ee1ee04a7..640c25237 100755
--- a/spec/unit/parser/ast/leaf.rb
+++ b/spec/unit/parser/ast/leaf.rb
@@ -21,6 +21,7 @@ describe Puppet::Parser::AST::Leaf do
         end
 
         it "should match values by equality" do
+            @value.stubs(:==).returns(false)
             @leaf.stubs(:safeevaluate).with(@scope).returns(@value)
             @value.expects(:==).with("value")
 
@@ -33,6 +34,12 @@ describe Puppet::Parser::AST::Leaf do
 
             @leaf.evaluate_match("value", @scope, :insensitive => true)
         end
+
+        it "should match undef if value is an empty string" do
+            @leaf.stubs(:safeevaluate).with(@scope).returns("")
+
+            @leaf.evaluate_match(:undef, @scope).should be_true
+        end
     end
 
     describe "when converting to string" do
@@ -72,12 +79,18 @@ describe Puppet::Parser::AST::String do
     end
 end
 
-describe Puppet::Parser::AST::Variable do
-    describe "when converting to string" do
-        it "should transform its value to a variable" do
-            value = stub 'value', :is_a? => true, :to_s => "myvar"
-            Puppet::Parser::AST::Variable.new( :value => value ).to_s.should == "\$myvar"
-        end
+describe Puppet::Parser::AST::Undef do
+    before :each do
+        @scope = stub 'scope'
+        @undef = Puppet::Parser::AST::Undef.new(:value => :undef)
+    end
+
+    it "should match undef with undef" do
+        @undef.evaluate_match(:undef, @scope).should be_true
+    end
+
+    it "should not match undef with an empty string" do
+        @undef.evaluate_match("", @scope).should be_false
     end
 end
 
@@ -158,6 +171,30 @@ describe Puppet::Parser::AST::Regex do
     end
 end
 
+describe Puppet::Parser::AST::Variable do
+    before :each do
+        @scope = stub 'scope'
+        @var = Puppet::Parser::AST::Variable.new(:value => "myvar")
+    end
+
+    it "should lookup the variable in scope" do
+        @scope.expects(:lookupvar).with("myvar", false).returns(:myvalue)
+        @var.safeevaluate(@scope).should == :myvalue
+    end
+
+    it "should return undef if the variable wasn't set" do
+        @scope.expects(:lookupvar).with("myvar", false).returns(:undefined)
+        @var.safeevaluate(@scope).should == :undef
+    end
+
+    describe "when converting to string" do
+        it "should transform its value to a variable" do
+            value = stub 'value', :is_a? => true, :to_s => "myvar"
+            Puppet::Parser::AST::Variable.new( :value => value ).to_s.should == "\$myvar"
+        end
+    end
+end
+
 describe Puppet::Parser::AST::HostName do
     before :each do
         @scope = stub 'scope'
diff --git a/test/language/ast/variable.rb b/test/language/ast/variable.rb
index 17e078b32..49b1dbbc2 100755
--- a/test/language/ast/variable.rb
+++ b/test/language/ast/variable.rb
@@ -22,7 +22,7 @@ class TestVariable < Test::Unit::TestCase
     end
 
     def test_evaluate
-        assert_equal("", @var.evaluate(@scope), "did not return empty string on unset var")
+        assert_equal(:undef, @var.evaluate(@scope), "did not return :undef on unset var")
         @scope.setvar(@name, "something")
         assert_equal("something", @var.evaluate(@scope), "incorrect variable value")
     end