Fix #1109 - allow empty if or else branches

This changesets allow empty if or else branches:

if true {
} else {
}

It works by emitting on the parser stack an AST node that doesn't
do anything (a no-op). This allows the less intrusive code
as no part of the if evaluation code has been touched.

2 files changed, 46 insertions, 0 deletions

diff --git a/spec/unit/parser/ast/nop.rb b/spec/unit/parser/ast/nop.rb
new file mode 100755
index 000000000..5a7132586
--- /dev/null
+++ b/spec/unit/parser/ast/nop.rb
@@ -0,0 +1,20 @@
+#!/usr/bin/env ruby
+
+require File.dirname(__FILE__) + '/../../../spec_helper'
+
+describe Puppet::Parser::AST::Nop do
+
+    before do
+        @scope = mock 'scope'
+    end
+
+    it "should do nothing on evaluation" do
+        Puppet::Parser::AST.expects(:safeevaluate).never
+        Puppet::Parser::AST::Nop.new({}).evaluate(@scope)
+    end
+
+    it "should not return anything" do
+        Puppet::Parser::AST::Nop.new({}).evaluate(@scope).should be_nil
+    end
+
+end
diff --git a/spec/unit/parser/parser.rb b/spec/unit/parser/parser.rb
index 0092a9970..c0d22a2cc 100755
--- a/spec/unit/parser/parser.rb
+++ b/spec/unit/parser/parser.rb
@@ -116,4 +116,30 @@ describe Puppet::Parser do
         
     end
      
+    describe Puppet::Parser, "when parsing if statements" do
+
+        it "should not raise errors with empty if" do
+            lambda { @parser.parse("if true { }") }.should_not raise_error
+        end
+
+        it "should not raise errors with empty else" do
+            lambda { @parser.parse("if false { notice('if') } else { }") }.should_not raise_error
+        end
+
+        it "should not raise errors with empty if and else" do
+            lambda { @parser.parse("if false { } else { }") }.should_not raise_error
+        end
+
+        it "should create a nop node for empty branch" do
+            AST::Nop.expects(:new)
+            @parser.parse("if true { }")
+        end
+
+        it "should create a nop node for empty else branch" do
+            AST::Nop.expects(:new)
+            @parser.parse("if true { notice('test') } else { }")
+        end
+
+    end
+
  end