diff --git a/lib/puppet/pops/issues.rb b/lib/puppet/pops/issues.rb
index 74cb5525f..f301609a4 100644
--- a/lib/puppet/pops/issues.rb
+++ b/lib/puppet/pops/issues.rb
@@ -1,452 +1,452 @@
 # Defines classes to deal with issues, and message formatting and defines constants with Issues.
 # @api public
 #
 module Puppet::Pops::Issues
   # Describes an issue, and can produce a message for an occurrence of the issue.
   #
   class Issue
     # The issue code
     # @return [Symbol]
     attr_reader :issue_code
 
     # A block producing the message
     # @return [Proc]
     attr_reader :message_block
 
     # Names that must be bound in an occurrence of the issue to be able to produce a message.
     # These are the names in addition to requirements stipulated by the Issue formatter contract; i.e. :label`,
     # and `:semantic`.
     #
     attr_reader :arg_names
 
     # If this issue can have its severity lowered to :warning, :deprecation, or :ignored
     attr_writer :demotable
     # Configures the Issue with required arguments (bound by occurrence), and a block producing a message.
     def initialize issue_code, *args, &block
       @issue_code = issue_code
       @message_block = block
       @arg_names = args
       @demotable = true
     end
 
     # Returns true if it is allowed to demote this issue
     def demotable?
       @demotable
     end
 
     # Formats a message for an occurrence of the issue with argument bindings passed in a hash.
     # The hash must contain a LabelProvider bound to the key `label` and the semantic model element
     # bound to the key `semantic`. All required arguments as specified by `arg_names` must be bound
     # in the given `hash`.
     # @api public
     #
     def format(hash ={})
       # Create a Message Data where all hash keys become methods for convenient interpolation
       # in issue text.
       msgdata = MessageData.new(*arg_names)
       begin
         # Evaluate the message block in the msg data's binding
         msgdata.format(hash, &message_block)
       rescue StandardError => e
         Puppet::Pops::Issues::MessageData
         raise RuntimeError, "Error while reporting issue: #{issue_code}. #{e.message}", caller
       end
     end
   end
 
   # Provides a binding of arguments passed to Issue.format to method names available
   # in the issue's message producing block.
   # @api private
   #
   class MessageData
     def initialize *argnames
       singleton = class << self; self end
       argnames.each do |name|
         singleton.send(:define_method, name) do
           @data[name]
         end
       end
     end
 
     def format(hash, &block)
       @data = hash
       instance_eval &block
     end
 
     # Returns the label provider given as a key in the hash passed to #format.
     # If given an argument, calls #label on the label provider (caller would otherwise have to
     # call label.label(it)
     #
     def label(it = nil)
       raise "Label provider key :label must be set to produce the text of the message!" unless @data[:label]
       it.nil? ? @data[:label] : @data[:label].label(it)
     end
 
     # Returns the label provider given as a key in the hash passed to #format.
     #
     def semantic
       raise "Label provider key :semantic must be set to produce the text of the message!" unless @data[:semantic]
       @data[:semantic]
     end
   end
 
   # Defines an issue with the given `issue_code`, additional required parameters, and a block producing a message.
   # The block is evaluated in the context of a MessageData which provides convenient access to all required arguments
   # via accessor methods. In addition to accessors for specified arguments, these are also available:
   # * `label` - a `LabelProvider` that provides human understandable names for model elements and production of article (a/an/the).
   # * `semantic` - the model element for which the issue is reported
   #
   # @param issue_code [Symbol] the issue code for the issue used as an identifier, should be the same as the constant
   #   the issue is bound to.
   # @param args [Symbol] required arguments that must be passed when formatting the message, may be empty
   # @param block [Proc] a block producing the message string, evaluated in a MessageData scope. The produced string
   #   should not end with a period as additional information may be appended.
   #
   # @see MessageData
   # @api public
   #
   def self.issue (issue_code, *args, &block)
     Issue.new(issue_code, *args, &block)
   end
 
   # Creates a non demotable issue.
   # @see Issue.issue
   #
   def self.hard_issue(issue_code, *args, &block)
     result = Issue.new(issue_code, *args, &block)
     result.demotable = false
     result
   end
 
   # @comment Here follows definitions of issues. The intent is to provide a list from which yardoc can be generated
   #   containing more detailed information / explanation of the issue.
   #   These issues are set as constants, but it is unfortunately not possible for the created object to easily know which
   #   name it is bound to. Instead the constant has to be repeated. (Alternatively, it could be done by instead calling
   #   #const_set on the module, but the extra work required to get yardoc output vs. the extra effort to repeat the name
   #   twice makes it not worth it (if doable at all, since there is no tag to artificially construct a constant, and
   #   the parse tag does not produce any result for a constant assignment).
 
   # This is allowed (3.1) and has not yet been deprecated.
   # @todo configuration
   #
   NAME_WITH_HYPHEN = issue :NAME_WITH_HYPHEN, :name do
     "#{label.a_an_uc(semantic)} may not have a name containing a hyphen. The name '#{name}' is not legal"
   end
 
   # When a variable name contains a hyphen and these are illegal.
   # It is possible to control if a hyphen is legal in a name or not using the setting TODO
   # @todo describe the setting
   # @api public
   # @todo configuration if this is error or warning
   #
   VAR_WITH_HYPHEN = issue :VAR_WITH_HYPHEN, :name do
     "A variable name may not contain a hyphen. The name '#{name}' is not legal"
   end
 
   # A class, definition, or node may only appear at top level or inside other classes
   # @todo Is this really true for nodes? Can they be inside classes? Isn't that too late?
   # @api public
   #
   NOT_TOP_LEVEL = hard_issue :NOT_TOP_LEVEL do
     "Classes, definitions, and nodes may only appear at toplevel or inside other classes"
   end
 
   CROSS_SCOPE_ASSIGNMENT = hard_issue :CROSS_SCOPE_ASSIGNMENT, :name do
     "Illegal attempt to assign to '#{name}'. Cannot assign to variables in other namespaces"
   end
 
   # Assignment can only be made to certain types of left hand expressions such as variables.
   ILLEGAL_ASSIGNMENT = hard_issue :ILLEGAL_ASSIGNMENT do
     "Illegal attempt to assign to '#{label.a_an(semantic)}'. Not an assignable reference"
   end
 
   # Variables are immutable, cannot reassign in the same assignment scope
   ILLEGAL_REASSIGNMENT = hard_issue :ILLEGAL_REASSIGNMENT, :name do
     "Cannot reassign variable #{name}"
   end
 
   ILLEGAL_RESERVED_ASSIGNMENT = hard_issue :ILLEGAL_RESERVED_ASSIGNMENT, :name do
     "Attempt to assign to a reserved variable name: '#{name}'"
   end
 
   # Assignment cannot be made to numeric match result variables
   ILLEGAL_NUMERIC_ASSIGNMENT = issue :ILLEGAL_NUMERIC_ASSIGNMENT, :varname do
     "Illegal attempt to assign to the numeric match result variable '$#{varname}'. Numeric variables are not assignable"
   end
 
   APPEND_FAILED = issue :APPEND_FAILED, :message do
     "Append assignment += failed with error: #{message}"
   end
 
   DELETE_FAILED = issue :DELETE_FAILED, :message do
     "'Delete' assignment -= failed with error: #{message}"
   end
 
   # parameters cannot have numeric names, clashes with match result variables
   ILLEGAL_NUMERIC_PARAMETER = issue :ILLEGAL_NUMERIC_PARAMETER, :name do
     "The numeric parameter name '$#{varname}' cannot be used (clashes with numeric match result variables)"
   end
 
   # In certain versions of Puppet it may be allowed to assign to a not already assigned key
   # in an array or a hash. This is an optional validation that may be turned on to prevent accidental
   # mutation.
   #
   ILLEGAL_INDEXED_ASSIGNMENT = issue :ILLEGAL_INDEXED_ASSIGNMENT do
     "Illegal attempt to assign via [index/key]. Not an assignable reference"
   end
 
   # When indexed assignment ($x[]=) is allowed, the leftmost expression must be
   # a variable expression.
   #
   ILLEGAL_ASSIGNMENT_VIA_INDEX = hard_issue :ILLEGAL_ASSIGNMENT_VIA_INDEX do
     "Illegal attempt to assign to #{label.a_an(semantic)} via [index/key]. Not an assignable reference"
   end
 
   # For unsupported operators (e.g. -= in puppet 3).
   #
   UNSUPPORTED_OPERATOR = hard_issue :UNSUPPORTED_OPERATOR, :operator do
     "The operator '#{operator}' in #{label.a_an(semantic)} is not supported."
   end
 
   # For non applicable operators (e.g. << on Hash).
   #
   OPERATOR_NOT_APPLICABLE = hard_issue :OPERATOR_NOT_APPLICABLE, :operator, :left_value do
     "Operator '#{operator}' is not applicable to #{label.a_an(left_value)}."
   end
 
   COMPARISON_NOT_POSSIBLE = hard_issue :COMPARISON_NOT_POSSIBLE, :operator, :left_value, :right_value, :detail do
     "Comparison of: #{label(left_value)} #{operator} #{label(right_value)}, is not possible. Caused by '#{detail}'."
   end
 
   MATCH_NOT_REGEXP = hard_issue :MATCH_NOT_REGEXP, :detail do
     "Can not convert right match operand to a regular expression. Caused by '#{detail}'."
   end
 
   MATCH_NOT_STRING = hard_issue :MATCH_NOT_STRING, :left_value do
     "Left match operand must result in a String value. Got #{label.a_an(left_value)}."
   end
 
   # Some expressions/statements may not produce a value (known as right-value, or rvalue).
   # This may vary between puppet versions.
   #
   NOT_RVALUE = issue :NOT_RVALUE do
     "Invalid use of expression. #{label.a_an_uc(semantic)} does not produce a value"
   end
 
   # Appending to attributes is only allowed in certain types of resource expressions.
   #
   ILLEGAL_ATTRIBUTE_APPEND = hard_issue :ILLEGAL_ATTRIBUTE_APPEND, :name, :parent do
     "Illegal +> operation on attribute #{name}. This operator can not be used in #{label.a_an(parent)}"
   end
 
   ILLEGAL_NAME = hard_issue :ILLEGAL_NAME, :name do
     "Illegal name. The given name #{name} does not conform to the naming rule /^((::)?[a-z_]\w*)(::[a-z]\w*)*$/"
   end
 
   ILLEGAL_VAR_NAME = hard_issue :ILLEGAL_VAR_NAME, :name do
-    "Illegal variable name, The given name '#{name}' does not conform to the naming rule /^((::)?[a-z_]\w*)(::[a-z]\w*)*$/"
+    "Illegal variable name, The given name '#{name}' does not conform to the naming rule /^((::)?[a-z]\w*)*((::)?[a-z_]\w*)$/"
   end
 
   ILLEGAL_NUMERIC_VAR_NAME = hard_issue :ILLEGAL_NUMERIC_VAR_NAME, :name do
     "Illegal numeric variable name, The given name '#{name}' must be a decimal value if it starts with a digit 0-9"
   end
 
   # In case a model is constructed programmatically, it must create valid type references.
   #
   ILLEGAL_CLASSREF = hard_issue :ILLEGAL_CLASSREF, :name do
     "Illegal type reference. The given name '#{name}' does not conform to the naming rule"
   end
 
   # This is a runtime issue - storeconfigs must be on in order to collect exported. This issue should be
   # set to :ignore when just checking syntax.
   # @todo should be a :warning by default
   #
   RT_NO_STORECONFIGS = issue :RT_NO_STORECONFIGS do
     "You cannot collect exported resources without storeconfigs being set; the collection will be ignored"
   end
 
   # This is a runtime issue - storeconfigs must be on in order to export a resource. This issue should be
   # set to :ignore when just checking syntax.
   # @todo should be a :warning by default
   #
   RT_NO_STORECONFIGS_EXPORT = issue :RT_NO_STORECONFIGS_EXPORT do
     "You cannot collect exported resources without storeconfigs being set; the export is ignored"
   end
 
   # A hostname may only contain letters, digits, '_', '-', and '.'.
   #
   ILLEGAL_HOSTNAME_CHARS = hard_issue :ILLEGAL_HOSTNAME_CHARS, :hostname do
     "The hostname '#{hostname}' contains illegal characters (only letters, digits, '_', '-', and '.' are allowed)"
   end
 
   # A hostname may only contain letters, digits, '_', '-', and '.'.
   #
   ILLEGAL_HOSTNAME_INTERPOLATION = hard_issue :ILLEGAL_HOSTNAME_INTERPOLATION do
     "An interpolated expression is not allowed in a hostname of a node"
   end
 
   # Issues when an expression is used where it is not legal.
   # E.g. an arithmetic expression where a hostname is expected.
   #
   ILLEGAL_EXPRESSION = hard_issue :ILLEGAL_EXPRESSION, :feature, :container do
     "Illegal expression. #{label.a_an_uc(semantic)} is unacceptable as #{feature} in #{label.a_an(container)}"
   end
 
   # Issues when an expression is used where it is not legal.
   # E.g. an arithmetic expression where a hostname is expected.
   #
   ILLEGAL_VARIABLE_EXPRESSION = hard_issue :ILLEGAL_VARIABLE_EXPRESSION do
     "Illegal variable expression. #{label.a_an_uc(semantic)} did not produce a variable name (String or Numeric)."
   end
 
   # Issues when an expression is used illegaly in a query.
   # query only supports == and !=, and not <, > etc.
   #
   ILLEGAL_QUERY_EXPRESSION = hard_issue :ILLEGAL_QUERY_EXPRESSION do
     "Illegal query expression. #{label.a_an_uc(semantic)} cannot be used in a query"
   end
 
   # If an attempt is made to make a resource default virtual or exported.
   #
   NOT_VIRTUALIZEABLE = hard_issue :NOT_VIRTUALIZEABLE do
     "Resource Defaults are not virtualizable"
   end
 
   # When an attempt is made to use multiple keys (to produce a range in Ruby - e.g. $arr[2,-1]).
   # This is not supported in 3x, but it allowed in 4x.
   #
   UNSUPPORTED_RANGE = issue :UNSUPPORTED_RANGE, :count do
     "Attempt to use unsupported range in #{label.a_an(semantic)}, #{count} values given for max 1"
   end
 
   DEPRECATED_NAME_AS_TYPE = issue :DEPRECATED_NAME_AS_TYPE, :name do
     "Resource references should now be capitalized. The given '#{name}' does not have the correct form"
   end
 
   ILLEGAL_RELATIONSHIP_OPERAND_TYPE = issue :ILLEGAL_RELATIONSHIP_OPERAND_TYPE, :operand do
     "Illegal relationship operand, can not form a relationship with #{label.a_an(operand)}. A Catalog type is required."
   end
 
   NOT_CATALOG_TYPE = issue :NOT_CATALOG_TYPE, :type do
     "Illegal relationship operand, can not form a relationship with something of type #{type}. A Catalog type is required."
   end
 
   BAD_STRING_SLICE_ARITY = issue :BAD_STRING_SLICE_ARITY, :actual do
     "String supports [] with one or two arguments. Got #{actual}"
   end
 
   BAD_STRING_SLICE_TYPE = issue :BAD_STRING_SLICE_TYPE, :actual do
     "String-Type [] requires all arguments to be integers (or default). Got #{actual}"
   end
 
   BAD_ARRAY_SLICE_ARITY = issue :BAD_ARRAY_SLICE_ARITY, :actual do
     "Array supports [] with one or two arguments. Got #{actual}"
   end
 
   BAD_HASH_SLICE_ARITY = issue :BAD_HASH_SLICE_ARITY, :actual do
     "Hash supports [] with one or more arguments. Got #{actual}"
   end
 
   BAD_INTEGER_SLICE_ARITY = issue :BAD_INTEGER_SLICE_ARITY, :actual do
     "Integer-Type supports [] with one or two arguments (from, to). Got #{actual}"
   end
 
   BAD_INTEGER_SLICE_TYPE = issue :BAD_INTEGER_SLICE_TYPE, :actual do
     "Integer-Type [] requires all arguments to be integers (or default). Got #{actual}"
   end
 
   BAD_COLLECTION_SLICE_TYPE = issue :BAD_COLLECTION_SLICE_TYPE, :actual do
     "A Type's size constraint arguments must be a single Integer type, or 1-2 integers (or default). Got #{label.a_an(actual)}"
   end
 
   BAD_FLOAT_SLICE_ARITY = issue :BAD_INTEGER_SLICE_ARITY, :actual do
     "Float-Type supports [] with one or two arguments (from, to). Got #{actual}"
   end
 
   BAD_FLOAT_SLICE_TYPE = issue :BAD_INTEGER_SLICE_TYPE, :actual do
     "Float-Type [] requires all arguments to be floats, or integers (or default). Got #{actual}"
   end
 
   BAD_SLICE_KEY_TYPE = issue :BAD_SLICE_KEY_TYPE, :left_value, :expected_classes, :actual do
     expected_text = if expected_classes.size > 1
       "one of #{expected_classes.join(', ')} are"
     else
       "#{expected_classes[0]} is"
     end
     "#{label.a_an_uc(left_value)}[] cannot use #{actual} where #{expected_text} expected"
   end
 
   BAD_TYPE_SLICE_TYPE = issue :BAD_TYPE_SLICE_TYPE, :base_type, :actual do
     "#{base_type}[] arguments must be types. Got #{actual}"
   end
 
   BAD_TYPE_SLICE_ARITY = issue :BAD_TYPE_SLICE_ARITY, :base_type, :min, :max, :actual do
     base_type_label = base_type.is_a?(String) ? base_type : label.a_an_uc(base_type)
     if max == -1 || max == 1.0 / 0.0 # Infinity
       "#{base_type_label}[] accepts #{min} or more arguments. Got #{actual}"
     elsif max
       "#{base_type_label}[] accepts #{min} to #{max} arguments. Got #{actual}"
     else
       "#{base_type_label}[] accepts #{min} #{label.plural_s(min, 'argument')}. Got #{actual}"
     end
   end
 
   BAD_TYPE_SPECIALIZATION = hard_issue :BAD_TYPE_SPECIALIZATION, :type, :message do
     "Error creating type specialization of #{label.a_an(type)}, #{message}"
   end
 
   ILLEGAL_TYPE_SPECIALIZATION = issue :ILLEGAL_TYPE_SPECIALIZATION, :kind do
     "Cannot specialize an already specialized #{kind} type"
   end
 
   ILLEGAL_RESOURCE_SPECIALIZATION = issue :ILLEGAL_RESOURCE_SPECIALIZATION, :actual do
     "First argument to Resource[] must be a resource type or a String. Got #{actual}."
   end
 
   ILLEGAL_HOSTCLASS_NAME = hard_issue :ILLEGAL_HOSTCLASS_NAME, :name do
     "Illegal Class name in class reference. #{label.a_an_uc(name)} cannot be used where a String is expected"
   end
 
   # Issues when an expression is used where it is not legal.
   # E.g. an arithmetic expression where a hostname is expected.
   #
   ILLEGAL_DEFINITION_NAME = hard_issue :ILLEGAL_DEFINTION_NAME, :name do
     "Unacceptable name. The name '#{name}' is unacceptable as the name of #{label.a_an(semantic)}"
   end
 
   NOT_NUMERIC = issue :NOT_NUMERIC, :value do
     "The value '#{value}' cannot be converted to Numeric."
   end
 
   UNKNOWN_FUNCTION = issue :UNKNOWN_FUNCTION, :name do
     "Unknown function: '#{name}'."
   end
 
   UNKNOWN_VARIABLE = issue :UNKNOWN_VARIABLE, :name do
     "Unknown variable: '#{name}'."
   end
 
   RUNTIME_ERROR = issue :RUNTIME_ERROR, :detail do
     "Error while evaluating #{label.a_an(semantic)}, #{detail}"
   end
 
   UNKNOWN_RESOURCE_TYPE = issue :UNKNOWN_RESOURCE_TYPE, :type_name do
     "Resource type not found: #{type_name.capitalize}"
   end
 
   UNKNOWN_RESOURCE = issue :UNKNOWN_RESOURCE, :type_name, :title do
     "Resource not found: #{type_name.capitalize}['#{title}']"
   end
 
   UNKNOWN_RESOURCE_PARAMETER = issue :UNKNOWN_RESOURCE_PARAMETER, :type_name, :title, :param_name do
     "The resource #{type_name.capitalize}['#{title}'] does not have a parameter called '#{param_name}'"
   end
 
   DIV_BY_ZERO = hard_issue :DIV_BY_ZERO do
     "Division by 0"
   end
 
   RESULT_IS_INFINITY = hard_issue :RESULT_IS_INFINITY, :operator do
     "The result of the #{operator} expression is Infinity"
   end
 end
diff --git a/lib/puppet/pops/patterns.rb b/lib/puppet/pops/patterns.rb
index 61246264f..a2534774d 100644
--- a/lib/puppet/pops/patterns.rb
+++ b/lib/puppet/pops/patterns.rb
@@ -1,43 +1,44 @@
 # The Patterns module contains common regular expression patters for the Puppet DSL language
 module Puppet::Pops::Patterns
 
   # NUMERIC matches hex, octal, decimal, and floating point and captures three parts
   # 0 = entire matched number, leading and trailing whitespace included
   # 1 = hexadecimal number
   # 2 = non hex integer portion, possibly with leading 0 (octal)
   # 3 = floating point part, starts with ".", decimals and optional exponent
   #
   # Thus, a hex number has group 1 value, an octal value has group 2 (if it starts with 0), and no group 3
   # and a floating point value has group 2 and group 3.
   #
   NUMERIC = %r{^\s*(?:(0[xX][0-9A-Fa-f]+)|(0?\d+)((?:\.\d+)?(?:[eE]-?\d+)?))\s*$}
 
   # ILLEGAL_P3_1_HOSTNAME matches if a hostname contains illegal characters.
   # This check does not prevent pathological names like 'a....b', '.....', "---". etc.
   ILLEGAL_HOSTNAME_CHARS = %r{[^-\w.]}
 
   # NAME matches a name the same way as the lexer.
   NAME = %r{\A((::)?[a-z]\w*)(::[a-z]\w*)*\z}
 
   # CLASSREF_EXT matches a class reference the same way as the lexer - i.e. the external source form
   # where each part must start with a capital letter A-Z.
   # This name includes hyphen, which may be illegal in some cases.
   #
   CLASSREF_EXT = %r{\A((::){0,1}[A-Z][\w]*)+\z}
 
   # CLASSREF matches a class reference the way it is represented internally in the
   # model (i.e. in lower case).
   # This name includes hyphen, which may be illegal in some cases.
   #
   CLASSREF = %r{\A((::){0,1}[a-z][\w]*)+\z}
 
   # DOLLAR_VAR matches a variable name including the initial $ character
   DOLLAR_VAR     = %r{\$(::)?(\w+::)*\w+}
 
   # VAR_NAME matches the name part of a variable (The $ character is not included)
-  VAR_NAME = %r{\A((::)?[a-z_]\w*)(::[a-z]\w*)*\z}
+  # Note, that only the final segment may start with an underscore.
+  VAR_NAME = %r{\A(:?(::)?[a-z]\w*)*(:?(::)?[a-z_]\w*)\z}
 
   # A Numeric var name must be the decimal number 0, or a decimal number not starting with 0
   NUMERIC_VAR_NAME = %r{\A(?:0|(?:[1-9][0-9]*))\z}
 
 end
diff --git a/spec/integration/parser/future_compiler_spec.rb b/spec/integration/parser/future_compiler_spec.rb
index b2c606e0f..5e56a7459 100644
--- a/spec/integration/parser/future_compiler_spec.rb
+++ b/spec/integration/parser/future_compiler_spec.rb
@@ -1,392 +1,416 @@
 #! /usr/bin/env ruby
 require 'spec_helper'
 require 'puppet/pops'
 require 'puppet/parser/parser_factory'
 require 'puppet_spec/compiler'
 require 'puppet_spec/pops'
 require 'puppet_spec/scope'
 require 'rgen/metamodel_builder'
 
 # Test compilation using the future evaluator
 #
 describe "Puppet::Parser::Compiler" do
   include PuppetSpec::Compiler
 
   before :each do
     Puppet[:parser] = 'future'
 
     # This is in the original test - what is this for? Does not seem to make a difference at all
     @scope_resource = stub 'scope_resource', :builtin? => true, :finish => nil, :ref => 'Class[main]'
     @scope = stub 'scope', :resource => @scope_resource, :source => mock("source")
   end
 
 
   after do
     Puppet.settings.clear
   end
 
   describe "the compiler when using future parser and evaluator" do
     it "should be able to determine the configuration version from a local version control repository" do
       pending("Bug #14071 about semantics of Puppet::Util::Execute on Windows", :if => Puppet.features.microsoft_windows?) do
         # This should always work, because we should always be
         # in the puppet repo when we run this.
         version = %x{git rev-parse HEAD}.chomp
 
         Puppet.settings[:config_version] = 'git rev-parse HEAD'
 
         parser = Puppet::Parser::ParserFactory.parser "development"
         compiler = Puppet::Parser::Compiler.new(Puppet::Node.new("testnode"))
         compiler.catalog.version.should == version
       end
     end
 
     it "should not create duplicate resources when a class is referenced both directly and indirectly by the node classifier (4792)" do
       Puppet[:code] = <<-PP
         class foo
         {
           notify { foo_notify: }
           include bar
         }
         class bar
         {
           notify { bar_notify: }
         }
       PP
 
       node = Puppet::Node.new("testnodex")
       node.classes = ['foo', 'bar']
       catalog = Puppet::Parser::Compiler.compile(node)
       node.classes = nil
       catalog.resource("Notify[foo_notify]").should_not be_nil
       catalog.resource("Notify[bar_notify]").should_not be_nil
     end
 
     describe "when resolving class references" do
       it "should favor local scope, even if there's an included class in topscope" do
         Puppet[:code] = <<-PP
           class experiment {
             class baz {
             }
             notify {"x" : require => Class[Baz] }
           }
           class baz {
           }
           include baz
           include experiment
           include experiment::baz
         PP
 
         catalog = Puppet::Parser::Compiler.compile(Puppet::Node.new("mynode"))
 
         notify_resource = catalog.resource( "Notify[x]" )
 
         notify_resource[:require].title.should == "Experiment::Baz"
       end
 
       it "should favor local scope, even if there's an unincluded class in topscope" do
         Puppet[:code] = <<-PP
           class experiment {
             class baz {
             }
             notify {"x" : require => Class[Baz] }
           }
           class baz {
           }
           include experiment
           include experiment::baz
         PP
 
         catalog = Puppet::Parser::Compiler.compile(Puppet::Node.new("mynode"))
 
         notify_resource = catalog.resource( "Notify[x]" )
 
         notify_resource[:require].title.should == "Experiment::Baz"
       end
     end
     describe "(ticket #13349) when explicitly specifying top scope" do
       ["class {'::bar::baz':}", "include ::bar::baz"].each do |include|
         describe "with #{include}" do
           it "should find the top level class" do
             Puppet[:code] = <<-MANIFEST
               class { 'foo::test': }
               class foo::test {
               	#{include}
               }
               class bar::baz {
               	notify { 'good!': }
               }
               class foo::bar::baz {
               	notify { 'bad!': }
               }
             MANIFEST
 
             catalog = Puppet::Parser::Compiler.compile(Puppet::Node.new("mynode"))
 
             catalog.resource("Class[Bar::Baz]").should_not be_nil
             catalog.resource("Notify[good!]").should_not be_nil
             catalog.resource("Class[Foo::Bar::Baz]").should be_nil
             catalog.resource("Notify[bad!]").should be_nil
           end
         end
       end
     end
 
     it "should recompute the version after input files are re-parsed" do
       Puppet[:code] = 'class foo { }'
       Time.stubs(:now).returns(1)
       node = Puppet::Node.new('mynode')
       Puppet::Parser::Compiler.compile(node).version.should == 1
       Time.stubs(:now).returns(2)
       Puppet::Parser::Compiler.compile(node).version.should == 1 # no change because files didn't change
       Puppet::Resource::TypeCollection.any_instance.stubs(:stale?).returns(true).then.returns(false) # pretend change
       Puppet::Parser::Compiler.compile(node).version.should == 2
     end
 
     ['define', 'class', 'node'].each do |thing|
       it "'#{thing}' is not allowed inside evaluated conditional constructs" do
         Puppet[:code] = <<-PP
           if true {
             #{thing} foo {
             }
             notify { decoy: }
           }
         PP
 
         begin
           catalog = Puppet::Parser::Compiler.compile(Puppet::Node.new("mynode"))
           raise "compilation should have raised Puppet::Error"
         rescue Puppet::Error => e
           e.message.should =~ /Classes, definitions, and nodes may only appear at toplevel/
         end
       end
     end
 
     ['define', 'class', 'node'].each do |thing|
       it "'#{thing}' is not allowed inside un-evaluated conditional constructs" do
         Puppet[:code] = <<-PP
           if false {
             #{thing} foo {
             }
             notify { decoy: }
           }
         PP
 
         begin
           catalog = Puppet::Parser::Compiler.compile(Puppet::Node.new("mynode"))
           raise "compilation should have raised Puppet::Error"
         rescue Puppet::Error => e
           e.message.should =~ /Classes, definitions, and nodes may only appear at toplevel/
         end
       end
     end
 
     describe "relationships can be formed" do
       def extract_name(ref)
         ref.sub(/File\[(\w+)\]/, '\1')
       end
 
       let(:node) { Puppet::Node.new('mynode') }
       let(:code) do
         <<-MANIFEST
           file { [a,b,c]:
             mode => 0644,
           }
           file { [d,e]:
             mode => 0755,
           }
         MANIFEST
       end
       let(:expected_relationships) { [] }
       let(:expected_subscriptions) { [] }
 
       before :each do
         Puppet[:parser] = 'future'
         Puppet[:code] = code
       end
 
       after :each do
         catalog = Puppet::Parser::Compiler.compile(node)
 
         resources = catalog.resources.select { |res| res.type == 'File' }
 
         actual_relationships, actual_subscriptions = [:before, :notify].map do |relation|
           resources.map do |res|
             dependents = Array(res[relation])
             dependents.map { |ref| [res.title, extract_name(ref)] }
           end.inject(&:concat)
         end
 
         actual_relationships.should =~ expected_relationships
         actual_subscriptions.should =~ expected_subscriptions
       end
 
       it "of regular type" do
         code << "File[a] -> File[b]"
 
         expected_relationships << ['a','b']
       end
 
       it "of subscription type" do
         code << "File[a] ~> File[b]"
 
         expected_subscriptions << ['a', 'b']
       end
 
       it "between multiple resources expressed as resource with multiple titles" do
         code << "File[a,b] -> File[c,d]"
 
         expected_relationships.concat [
           ['a', 'c'],
           ['b', 'c'],
           ['a', 'd'],
           ['b', 'd'],
         ]
       end
 
       it "between collection expressions" do
         code << "File <| mode == 0644 |> -> File <| mode == 0755 |>"
 
         expected_relationships.concat [
           ['a', 'd'],
           ['b', 'd'],
           ['c', 'd'],
           ['a', 'e'],
           ['b', 'e'],
           ['c', 'e'],
         ]
       end
 
       it "between resources expressed as Strings" do
         code << "'File[a]' -> 'File[b]'"
 
         expected_relationships << ['a', 'b']
       end
 
       it "between resources expressed as variables" do
         code << <<-MANIFEST
           $var = File[a]
           $var -> File[b]
         MANIFEST
 
         expected_relationships << ['a', 'b']
       end
 
       it "between resources expressed as case statements" do
         code << <<-MANIFEST
           $var = 10
           case $var {
             10: {
               file { s1: }
             }
             12: {
               file { s2: }
             }
           }
           ->
           case $var + 2 {
             10: {
               file { t1: }
             }
             12: {
               file { t2: }
             }
           }
         MANIFEST
 
         expected_relationships << ['s1', 't2']
       end
 
       it "using deep access in array" do
         code << <<-MANIFEST
           $var = [ [ [ File[a], File[b] ] ] ]
           $var[0][0][0] -> $var[0][0][1]
         MANIFEST
 
         expected_relationships << ['a', 'b']
       end
 
       it "using deep access in hash" do
         code << <<-MANIFEST
           $var = {'foo' => {'bar' => {'source' => File[a], 'target' => File[b]}}}
           $var[foo][bar][source] -> $var[foo][bar][target]
         MANIFEST
 
         expected_relationships << ['a', 'b']
       end
 
       it "using resource declarations" do
         code << "file { l: } -> file { r: }"
 
         expected_relationships << ['l', 'r']
       end
 
       it "between entries in a chain of relationships" do
         code << "File[a] -> File[b] ~> File[c] <- File[d] <~ File[e]"
 
         expected_relationships << ['a', 'b'] << ['d', 'c']
         expected_subscriptions << ['b', 'c'] << ['e', 'd']
       end
     end
 
+    context "when dealing with variable references" do
+      it 'an initial underscore in a variable name is ok' do
+        node = Puppet::Node.new("testing_x")
+        catalog = compile_to_catalog(<<-MANIFEST, node)
+          class a { $_a = 10}
+          include a
+          notify { 'test': message => $a::_a }
+        MANIFEST
+
+        catalog.resource("Notify[test]")[:message].should == 10
+      end
+
+      it 'an initial underscore in not ok if elsewhere than last segment' do
+        node = Puppet::Node.new("testing_x")
+        expect { 
+          catalog = compile_to_catalog(<<-MANIFEST, node)
+          class a { $_a = 10}
+          include a
+          notify { 'test': message => $_a::_a }
+        MANIFEST
+          }.to raise_error(/Illegal variable name/)
+      end
+    end
+
     context 'when working with the trusted data hash' do
       context 'and have opted in to hashed_node_data' do
         before :each do
           Puppet[:trusted_node_data] = true
         end
 
         it 'should make $trusted available' do
           node = Puppet::Node.new("testing")
           node.trusted_data = { "data" => "value" }
 
           catalog = compile_to_catalog(<<-MANIFEST, node)
             notify { 'test': message => $trusted[data] }
           MANIFEST
 
           catalog.resource("Notify[test]")[:message].should == "value"
         end
 
         it 'should not allow assignment to $trusted' do
           node = Puppet::Node.new("testing")
           node.trusted_data = { "data" => "value" }
 
           expect do
             catalog = compile_to_catalog(<<-MANIFEST, node)
               $trusted = 'changed'
               notify { 'test': message => $trusted == 'changed' }
             MANIFEST
             catalog.resource("Notify[test]")[:message].should == true
           end.to raise_error(Puppet::Error, /Attempt to assign to a reserved variable name: 'trusted'/)
         end
       end
 
       context 'and have not opted in to hashed_node_data' do
         before :each do
           Puppet[:trusted_node_data] = false
         end
 
         it 'should not make $trusted available' do
           node = Puppet::Node.new("testing")
           node.trusted_data = { "data" => "value" }
 
           catalog = compile_to_catalog(<<-MANIFEST, node)
             notify { 'test': message => ($trusted == undef) }
           MANIFEST
 
           catalog.resource("Notify[test]")[:message].should == true
         end
 
         it 'should allow assignment to $trusted' do
           node = Puppet::Node.new("testing")
 
           catalog = compile_to_catalog(<<-MANIFEST, node)
             $trusted = 'changed'
             notify { 'test': message => $trusted == 'changed' }
           MANIFEST
 
           catalog.resource("Notify[test]")[:message].should == true
         end
       end
     end
   end
 
 end
diff --git a/spec/unit/pops/evaluator/evaluating_parser_spec.rb b/spec/unit/pops/evaluator/evaluating_parser_spec.rb
index 43cfb7737..127427dc8 100644
--- a/spec/unit/pops/evaluator/evaluating_parser_spec.rb
+++ b/spec/unit/pops/evaluator/evaluating_parser_spec.rb
@@ -1,967 +1,977 @@
 #! /usr/bin/env ruby
 require 'spec_helper'
 
 require 'puppet/pops'
 require 'puppet/pops/evaluator/evaluator_impl'
 require 'puppet_spec/pops'
 require 'puppet_spec/scope'
 require 'puppet/parser/e4_parser_adapter'
 
 
 # relative to this spec file (./) does not work as this file is loaded by rspec
 #require File.join(File.dirname(__FILE__), '/evaluator_rspec_helper')
 
 describe 'Puppet::Pops::Evaluator::EvaluatorImpl' do
   include PuppetSpec::Pops
   include PuppetSpec::Scope
   before(:each) do
     Puppet[:strict_variables] = true
 
     # These must be set since the is 3x logic that triggers on these even if the tests are explicit
     # about selection of parser and evaluator
     #
     Puppet[:parser] = 'future'
     Puppet[:evaluator] = 'future'
   end
 
   let(:parser) { Puppet::Pops::Parser::EvaluatingParser::Transitional.new }
   let(:node) { 'node.example.com' }
   let(:scope) { s = create_test_scope_for_node(node); s }
   types = Puppet::Pops::Types::TypeFactory
 
   context "When evaluator evaluates literals" do
     {
       "1"             => 1,
       "010"           => 8,
       "0x10"          => 16,
       "3.14"          => 3.14,
       "0.314e1"       => 3.14,
       "31.4e-1"       => 3.14,
       "'1'"           => '1',
       "'banana'"      => 'banana',
       '"banana"'      => 'banana',
       "banana"        => 'banana',
       "banana::split" => 'banana::split',
       "false"         => false,
       "true"          => true,
       "Array"         => types.array_of_data(),
       "/.*/"          => /.*/
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
   end
 
   context "When the evaluator evaluates Lists and Hashes" do
     {
       "[]"                                              => [],
       "[1,2,3]"                                         => [1,2,3],
       "[1,[2.0, 2.1, [2.2]],[3.0, 3.1]]"                => [1,[2.0, 2.1, [2.2]],[3.0, 3.1]],
       "[2 + 2]"                                         => [4],
       "[1,2,3] == [1,2,3]"                              => true,
       "[1,2,3] != [2,3,4]"                              => true,
       "[1,2,3] == [2,2,3]"                              => false,
       "[1,2,3] != [1,2,3]"                              => false,
       "[1,2,3][2]"                                      => 3,
       "[1,2,3] + [4,5]"                                 => [1,2,3,4,5],
       "[1,2,3] + [[4,5]]"                               => [1,2,3,[4,5]],
       "[1,2,3] + 4"                                     => [1,2,3,4],
       "[1,2,3] << [4,5]"                                => [1,2,3,[4,5]],
       "[1,2,3] << {'a' => 1, 'b'=>2}"                   => [1,2,3,{'a' => 1, 'b'=>2}],
       "[1,2,3] << 4"                                    => [1,2,3,4],
       "[1,2,3,4] - [2,3]"                               => [1,4],
       "[1,2,3,4] - [2,5]"                               => [1,3,4],
       "[1,2,3,4] - 2"                                   => [1,3,4],
       "[1,2,3,[2],4] - 2"                               => [1,3,[2],4],
       "[1,2,3,[2,3],4] - [[2,3]]"                       => [1,2,3,4],
       "[1,2,3,3,2,4,2,3] - [2,3]"                       => [1,4],
       "[1,2,3,['a',1],['b',2]] - {'a' => 1, 'b'=>2}"    => [1,2,3],
       "[1,2,3,{'a'=>1,'b'=>2}] - [{'a' => 1, 'b'=>2}]"  => [1,2,3],
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
     {
       "[1,2,3] + {'a' => 1, 'b'=>2}"                    => [1,2,3,['a',1],['b',2]],
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           # This test must be done with match_array since the order of the hash
           # is undefined and Ruby 1.8.7 and 1.9.3 produce different results.
           expect(parser.evaluate_string(scope, source, __FILE__)).to match_array(result)
         end
       end
 
     {
       "[1,2,3][a]" => :error,
     }.each do |source, result|
         it "should parse and raise error for '#{source}'" do
           expect { parser.evaluate_string(scope, source, __FILE__) }.to raise_error(Puppet::ParseError)
         end
       end
 
     {
       "{}"                                       => {},
       "{'a'=>1,'b'=>2}"                          => {'a'=>1,'b'=>2},
       "{'a'=>1,'b'=>{'x'=>2.1,'y'=>2.2}}"        => {'a'=>1,'b'=>{'x'=>2.1,'y'=>2.2}},
       "{'a'=> 2 + 2}"                            => {'a'=> 4},
       "{'a'=> 1, 'b'=>2} == {'a'=> 1, 'b'=>2}"   => true,
       "{'a'=> 1, 'b'=>2} != {'x'=> 1, 'b'=>2}"   => true,
       "{'a'=> 1, 'b'=>2} == {'a'=> 2, 'b'=>3}"   => false,
       "{'a'=> 1, 'b'=>2} != {'a'=> 1, 'b'=>2}"   => false,
       "{a => 1, b => 2}[b]"                      => 2,
       "{2+2 => sum, b => 2}[4]"                  => 'sum',
       "{'a'=>1, 'b'=>2} + {'c'=>3}"              => {'a'=>1,'b'=>2,'c'=>3},
       "{'a'=>1, 'b'=>2} + {'b'=>3}"              => {'a'=>1,'b'=>3},
       "{'a'=>1, 'b'=>2} + ['c', 3, 'b', 3]"      => {'a'=>1,'b'=>3, 'c'=>3},
       "{'a'=>1, 'b'=>2} + [['c', 3], ['b', 3]]"  => {'a'=>1,'b'=>3, 'c'=>3},
       "{'a'=>1, 'b'=>2} - {'b' => 3}"            => {'a'=>1},
       "{'a'=>1, 'b'=>2, 'c'=>3} - ['b', 'c']"    => {'a'=>1},
       "{'a'=>1, 'b'=>2, 'c'=>3} - 'c'"           => {'a'=>1, 'b'=>2},
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
     {
       "{'a' => 1, 'b'=>2} << 1" => :error,
     }.each do |source, result|
         it "should parse and raise error for '#{source}'" do
           expect { parser.evaluate_string(scope, source, __FILE__) }.to raise_error(Puppet::ParseError)
         end
       end
   end
 
   context "When the evaluator perform comparisons" do
     {
       "'a' == 'a'"     => true,
       "'a' == 'b'"     => false,
       "'a' != 'a'"     => false,
       "'a' != 'b'"     => true,
       "'a' < 'b' "     => true,
       "'a' < 'a' "     => false,
       "'b' < 'a' "     => false,
       "'a' <= 'b'"     => true,
       "'a' <= 'a'"     => true,
       "'b' <= 'a'"     => false,
       "'a' > 'b' "     => false,
       "'a' > 'a' "     => false,
       "'b' > 'a' "     => true,
       "'a' >= 'b'"     => false,
       "'a' >= 'a'"     => true,
       "'b' >= 'a'"     => true,
       "'a' == 'A'"     => true,
       "'a' != 'A'"     => false,
       "'a' >  'A'"     => false,
       "'a' >= 'A'"     => true,
       "'A' <  'a'"     => false,
       "'A' <= 'a'"     => true,
       "1 == 1"         => true,
       "1 == 2"         => false,
       "1 != 1"         => false,
       "1 != 2"         => true,
       "1 < 2 "         => true,
       "1 < 1 "         => false,
       "2 < 1 "         => false,
       "1 <= 2"         => true,
       "1 <= 1"         => true,
       "2 <= 1"         => false,
       "1 > 2 "         => false,
       "1 > 1 "         => false,
       "2 > 1 "         => true,
       "1 >= 2"         => false,
       "1 >= 1"         => true,
       "2 >= 1"         => true,
       "1 == 1.0 "      => true,
       "1 < 1.1  "      => true,
       "'1' < 1.1"      => true,
       "1.0 == 1 "      => true,
       "1.0 < 2  "      => true,
       "'1.0' < 1.1"    => true,
       "'1.0' < 'a'"    => true,
       "'1.0' < '' "    => true,
       "'1.0' < ' '"    => true,
       "'a' > '1.0'"    => true,
       "/.*/ == /.*/ "  => true,
       "/.*/ != /a.*/"  => true,
       "true  == true " => true,
       "false == false" => true,
       "true == false"  => false,
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
    {
       "'a' =~ /.*/"                     => true,
       "'a' =~ '.*'"                     => true,
       "/.*/ != /a.*/"                   => true,
       "'a' !~ /b.*/"                    => true,
       "'a' !~ 'b.*'"                    => true,
       '$x = a; a =~ "$x.*"'             => true,
       "a =~ Pattern['a.*']"             => true,
       "a =~ Regexp['a.*']"              => true,
       "$x = /a.*/ a =~ $x"              => true,
       "$x = Pattern['a.*'] a =~ $x"     => true,
       "1 =~ Integer"                    => true,
       "1 !~ Integer"                    => false,
       "[1,2,3] =~ Array[Integer[1,10]]" => true,
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
     {
       "666 =~ /6/"    => :error,
       "[a] =~ /a/"    => :error,
       "{a=>1} =~ /a/" => :error,
        "/a/ =~ /a/"    => :error,
       "Array =~ /A/"  => :error,
     }.each do |source, result|
         it "should parse and raise error for '#{source}'" do
           expect { parser.evaluate_string(scope, source, __FILE__) }.to raise_error(Puppet::ParseError)
         end
       end
 
     {
       "1 in [1,2,3]"                  => true,
       "4 in [1,2,3]"                  => false,
       "a in {x=>1, a=>2}"             => true,
       "z in {x=>1, a=>2}"             => false,
       "ana in bananas"                => true,
       "xxx in bananas"                => false,
       "/ana/ in bananas"              => true,
       "/xxx/ in bananas"              => false,
       "ANA in bananas"                => false, # ANA is a type, not a String
       "'ANA' in bananas"              => true,
       "ana in 'BANANAS'"              => true,
       "/ana/ in 'BANANAS'"            => false,
       "/ANA/ in 'BANANAS'"            => true,
       "xxx in 'BANANAS'"              => false,
       "[2,3] in [1,[2,3],4]"          => true,
       "[2,4] in [1,[2,3],4]"          => false,
       "[a,b] in ['A',['A','B'],'C']"  => true,
       "[x,y] in ['A',['A','B'],'C']"  => false,
       "a in {a=>1}"                   => true,
       "x in {a=>1}"                   => false,
       "'A' in {a=>1}"                 => true,
       "'X' in {a=>1}"                 => false,
       "a in {'A'=>1}"                 => true,
       "x in {'A'=>1}"                 => false,
       "/xxx/ in {'aaaxxxbbb'=>1}"     => true,
       "/yyy/ in {'aaaxxxbbb'=>1}"     => false,
       "15 in [1, 0xf]"                => true,
       "15 in [1, '0xf']"              => true,
       "'15' in [1, 0xf]"              => true,
       "15 in [1, 115]"                => false,
       "1 in [11, '111']"              => false,
       "'1' in [11, '111']"            => false,
       "Array[Integer] in [2, 3]"      => false,
       "Array[Integer] in [2, [3, 4]]" => true,
       "Array[Integer] in [2, [a, 4]]" => false,
       "Integer in { 2 =>'a'}"         => true,
       "Integer[5,10] in [1,5,3]"      => true,
       "Integer[5,10] in [1,2,3]"      => false,
       "Integer in {'a'=>'a'}"         => false,
       "Integer in {'a'=>1}"           => false,
     }.each do |source, result|
       it "should parse and evaluate the expression '#{source}' to #{result}" do
         parser.evaluate_string(scope, source, __FILE__).should == result
       end
     end
 
     {
       'Object'  => ['Data', 'Scalar', 'Numeric', 'Integer', 'Float', 'Boolean', 'String', 'Pattern', 'Collection',
                     'Array', 'Hash', 'CatalogEntry', 'Resource', 'Class', 'Undef', 'File', 'NotYetKnownResourceType'],
 
       # Note, Data > Collection is false (so not included)
       'Data'    => ['Scalar', 'Numeric', 'Integer', 'Float', 'Boolean', 'String', 'Pattern', 'Array', 'Hash',],
       'Scalar' => ['Numeric', 'Integer', 'Float', 'Boolean', 'String', 'Pattern'],
       'Numeric' => ['Integer', 'Float'],
       'CatalogEntry' => ['Class', 'Resource', 'File', 'NotYetKnownResourceType'],
       'Integer[1,10]' => ['Integer[2,3]'],
     }.each do |general, specials|
       specials.each do |special |
         it "should compute that #{general} > #{special}" do
           parser.evaluate_string(scope, "#{general} > #{special}", __FILE__).should == true
         end
         it "should compute that  #{special} < #{general}" do
           parser.evaluate_string(scope, "#{special} < #{general}", __FILE__).should == true
         end
         it "should compute that #{general} != #{special}" do
           parser.evaluate_string(scope, "#{special} != #{general}", __FILE__).should == true
         end
       end
     end
 
     {
       'Integer[1,10] > Integer[2,3]'   => true,
       'Integer[1,10] == Integer[2,3]'  => false,
       'Integer[1,10] > Integer[0,5]'   => false,
       'Integer[1,10] > Integer[1,10]'  => false,
       'Integer[1,10] >= Integer[1,10]' => true,
       'Integer[1,10] == Integer[1,10]' => true,
     }.each do |source, result|
         it "should parse and evaluate the integer range comparison expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
   end
 
   context "When the evaluator performs arithmetic" do
     context "on Integers" do
       {  "2+2"    => 4,
          "2 + 2"  => 4,
          "7 - 3"  => 4,
          "6 * 3"  => 18,
          "6 / 3"  => 2,
          "6 % 3"  => 0,
          "10 % 3" =>  1,
          "-(6/3)" => -2,
          "-6/3  " => -2,
          "8 >> 1" => 4,
          "8 << 1" => 16,
       }.each do |source, result|
           it "should parse and evaluate the expression '#{source}' to #{result}" do
             parser.evaluate_string(scope, source, __FILE__).should == result
           end
         end
 
     context "on Floats" do
       {
         "2.2 + 2.2"  => 4.4,
         "7.7 - 3.3"  => 4.4,
         "6.1 * 3.1"  => 18.91,
         "6.6 / 3.3"  => 2.0,
         "-(6.0/3.0)" => -2.0,
         "-6.0/3.0 "  => -2.0,
       }.each do |source, result|
           it "should parse and evaluate the expression '#{source}' to #{result}" do
             parser.evaluate_string(scope, source, __FILE__).should == result
           end
         end
 
       {
         "3.14 << 2" => :error,
         "3.14 >> 2" => :error,
         "6.6 % 3.3"  => 0.0,
         "10.0 % 3.0" =>  1.0,
       }.each do |source, result|
           it "should parse and raise error for '#{source}'" do
             expect { parser.evaluate_string(scope, source, __FILE__) }.to raise_error(Puppet::ParseError)
           end
         end
     end
 
     context "on strings requiring boxing to Numeric" do
       {
         "'2' + '2'"       => 4,
         "'2.2' + '2.2'"   => 4.4,
         "'0xF7' + '010'"  => 0xFF,
         "'0xF7' + '0x8'"  => 0xFF,
         "'0367' + '010'"  => 0xFF,
         "'012.3' + '010'" => 20.3,
       }.each do |source, result|
           it "should parse and evaluate the expression '#{source}' to #{result}" do
             parser.evaluate_string(scope, source, __FILE__).should == result
           end
         end
 
       {
         "'0888' + '010'"   => :error,
         "'0xWTF' + '010'"  => :error,
         "'0x12.3' + '010'" => :error,
         "'0x12.3' + '010'" => :error,
       }.each do |source, result|
           it "should parse and raise error for '#{source}'" do
             expect { parser.evaluate_string(scope, source, __FILE__) }.to raise_error(Puppet::ParseError)
           end
         end
       end
     end
   end # arithmetic
 
   context "When the evaluator evaluates assignment" do
     {
       "$a = 5"                     => 5,
       "$a = 5; $a"                 => 5,
       "$a = 5; $b = 6; $a"         => 5,
       "$a = $b = 5; $a == $b"      => true,
       "$a = [1,2,3]; [x].map |$x| { $a += x; $a }"      => [[1,2,3,'x']],
       "$a = [a,x,c]; [x].map |$x| { $a -= x; $a }"      => [['a','c']],
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
     {
       "[a,b,c] = [1,2,3]; $a == 1 and $b == 2 and $c == 3"               => :error,
       "[a,b,c] = {b=>2,c=>3,a=>1}; $a == 1 and $b == 2 and $c == 3"      => :error,
       "$a = [1,2,3]; [x].collect |$x| { [a] += x; $a }"                  => :error,
       "$a = [a,x,c]; [x].collect |$x| { [a] -= x; $a }"                  => :error,
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           expect { parser.evaluate_string(scope, source, __FILE__)}.to raise_error(Puppet::ParseError)
         end
       end
   end
 
   context "When the evaluator evaluates conditionals" do
     {
       "if true {5}"                     => 5,
       "if false {5}"                    => nil,
       "if false {2} else {5}"           => 5,
       "if false {2} elsif true {5}"     => 5,
       "if false {2} elsif false {5}"    => nil,
       "unless false {5}"                => 5,
       "unless true {5}"                 => nil,
       "unless true {2} else {5}"        => 5,
       "$a = if true {5} $a"                     => 5,
       "$a = if false {5} $a"                    => nil,
       "$a = if false {2} else {5} $a"           => 5,
       "$a = if false {2} elsif true {5} $a"     => 5,
       "$a = if false {2} elsif false {5} $a"    => nil,
       "$a = unless false {5} $a"                => 5,
       "$a = unless true {5} $a"                 => nil,
       "$a = unless true {2} else {5} $a"        => 5,
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
     {
       "case 1 { 1 : { yes } }"                               => 'yes',
       "case 2 { 1,2,3 : { yes} }"                            => 'yes',
       "case 2 { 1,3 : { no } 2: { yes} }"                    => 'yes',
       "case 2 { 1,3 : { no } 5: { no } default: { yes }}"    => 'yes',
       "case 2 { 1,3 : { no } 5: { no } }"                    => nil,
       "case 'banana' { 1,3 : { no } /.*ana.*/: { yes } }"    => 'yes',
       "case 'banana' { /.*(ana).*/: { $1 } }"                => 'ana',
       "case [1] { Array : { yes } }"                         => 'yes',
       "case [1] {
          Array[String] : { no }
          Array[Integer]: { yes }
       }"                                                     => 'yes',
       "case 1 {
          Integer : { yes }
          Type[Integer] : { no } }"                           => 'yes',
       "case Integer {
          Integer : { no }
          Type[Integer] : { yes } }"                          => 'yes',
 
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
     {
       "2 ? { 1 => no, 2 => yes}"                          => 'yes',
       "3 ? { 1 => no, 2 => no}"                           => nil,
       "3 ? { 1 => no, 2 => no, default => yes }"          => 'yes',
       "3 ? { 1 => no, default => yes, 3 => no }"          => 'yes',
       "'banana' ? { /.*(ana).*/  => $1 }"                 => 'ana',
       "[2] ? { Array[String] => yes, Array => yes}"       => 'yes',
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
   end
 
   context "When evaluator performs [] operations" do
     {
       "[1,2,3][0]"      => 1,
       "[1,2,3][2]"      => 3,
       "[1,2,3][3]"      => nil,
       "[1,2,3][-1]"     => 3,
       "[1,2,3][-2]"     => 2,
       "[1,2,3][-4]"     => nil,
       "[1,2,3,4][0,2]"  => [1,2],
       "[1,2,3,4][1,3]"  => [2,3,4],
       "[1,2,3,4][-2,2]"  => [3,4],
       "[1,2,3,4][-3,2]"  => [2,3],
       "[1,2,3,4][3,5]"   => [4],
       "[1,2,3,4][5,2]"   => [],
       "[1,2,3,4][0,-1]"  => [1,2,3,4],
       "[1,2,3,4][0,-2]"  => [1,2,3],
       "[1,2,3,4][0,-4]"  => [1],
       "[1,2,3,4][0,-5]"  => [],
       "[1,2,3,4][-5,2]"  => [1],
       "[1,2,3,4][-5,-3]" => [1,2],
       "[1,2,3,4][-6,-3]" => [1,2],
       "[1,2,3,4][2,-3]"  => [],
     }.each do |source, result|
       it "should parse and evaluate the expression '#{source}' to #{result}" do
         parser.evaluate_string(scope, source, __FILE__).should == result
       end
     end
 
     {
       "{a=>1, b=>2, c=>3}[a]"                => 1,
       "{a=>1, b=>2, c=>3}[c]"                => 3,
       "{a=>1, b=>2, c=>3}[x]"                => nil,
       "{a=>1, b=>2, c=>3}[c,b]"              => [3,2],
       "{a=>1, b=>2, c=>3}[a,b,c]"            => [1,2,3],
       "{a=>{b=>{c=>'it works'}}}[a][b][c]"   => 'it works',
       "$a = {undef => 10} $a[free_lunch]"     => nil,
       "$a = {undef => 10} $a[undef]"          => 10,
       "$a = {undef => 10} $a[$a[free_lunch]]" => 10,
       "$a = {} $a[free_lunch] == undef"       => true,
     }.each do |source, result|
       it "should parse and evaluate the expression '#{source}' to #{result}" do
         parser.evaluate_string(scope, source, __FILE__).should == result
       end
     end
 
     {
       "'abc'[0]"      => 'a',
       "'abc'[2]"      => 'c',
       "'abc'[-1]"     => 'c',
       "'abc'[-2]"     => 'b',
       "'abc'[-3]"     => 'a',
       "'abc'[-4]"     => '',
       "'abc'[3]"      => '',
       "abc[0]"        => 'a',
       "abc[2]"        => 'c',
       "abc[-1]"       => 'c',
       "abc[-2]"       => 'b',
       "abc[-3]"       => 'a',
       "abc[-4]"       => '',
       "abc[3]"        => '',
       "'abcd'[0,2]"   => 'ab',
       "'abcd'[1,3]"   => 'bcd',
       "'abcd'[-2,2]"  => 'cd',
       "'abcd'[-3,2]"  => 'bc',
       "'abcd'[3,5]"   => 'd',
       "'abcd'[5,2]"   => '',
       "'abcd'[0,-1]"  => 'abcd',
       "'abcd'[0,-2]"  => 'abc',
       "'abcd'[0,-4]"  => 'a',
       "'abcd'[0,-5]"  => '',
       "'abcd'[-5,2]"  => 'a',
       "'abcd'[-5,-3]" => 'ab',
       "'abcd'[-6,-3]" => 'ab',
       "'abcd'[2,-3]"  => '',
    }.each do |source, result|
       it "should parse and evaluate the expression '#{source}' to #{result}" do
         parser.evaluate_string(scope, source, __FILE__).should == result
       end
     end
 
     # Type operations (full set tested by tests covering type calculator)
     {
       "Array[Integer]"                  => types.array_of(types.integer),
       "Array[Integer,1]"                => types.constrain_size(types.array_of(types.integer),1, :default),
       "Array[Integer,1,2]"              => types.constrain_size(types.array_of(types.integer),1, 2),
       "Array[Integer,Integer[1,2]]"     => types.constrain_size(types.array_of(types.integer),1, 2),
       "Array[Integer,Integer[1]]"       => types.constrain_size(types.array_of(types.integer),1, :default),
       "Hash[Integer,Integer]"           => types.hash_of(types.integer, types.integer),
       "Hash[Integer,Integer,1]"         => types.constrain_size(types.hash_of(types.integer, types.integer),1, :default),
       "Hash[Integer,Integer,1,2]"       => types.constrain_size(types.hash_of(types.integer, types.integer),1, 2),
       "Hash[Integer,Integer,Integer[1,2]]" => types.constrain_size(types.hash_of(types.integer, types.integer),1, 2),
       "Hash[Integer,Integer,Integer[1]]"   => types.constrain_size(types.hash_of(types.integer, types.integer),1, :default),
       "Resource[File]"                  => types.resource('File'),
       "Resource['File']"                => types.resource(types.resource('File')),
       "File[foo]"                       => types.resource('file', 'foo'),
       "File[foo, bar]"                  => [types.resource('file', 'foo'), types.resource('file', 'bar')],
       "Pattern[a, /b/, Pattern[c], Regexp[d]]"  => types.pattern('a', 'b', 'c', 'd'),
       "String[1,2]"                     => types.constrain_size(types.string,1, 2),
       "String[Integer[1,2]]"            => types.constrain_size(types.string,1, 2),
       "String[Integer[1]]"              => types.constrain_size(types.string,1, :default),
     }.each do |source, result|
       it "should parse and evaluate the expression '#{source}' to #{result}" do
         parser.evaluate_string(scope, source, __FILE__).should == result
       end
     end
 
     # LHS where [] not supported, and missing key(s)
     {
       "Array[]"                    => :error,
       "'abc'[]"                    => :error,
       "Resource[]"                 => :error,
       "File[]"                     => :error,
       "String[]"                   => :error,
       "1[]"                        => :error,
       "3.14[]"                     => :error,
       "/.*/[]"                     => :error,
       "$a=[1] $a[]"                => :error,
     }.each do |source, result|
       it "should parse and evaluate the expression '#{source}' to #{result}" do
         expect { parser.evaluate_string(scope, source, __FILE__)}.to raise_error(/Syntax error/)
       end
     end
 
     # Errors when wrong number/type of keys are used
     {
       "Array[0]"                    => 'Array-Type[] arguments must be types. Got Fixnum',
       "Hash[0]"                     => 'Hash-Type[] arguments must be types. Got Fixnum',
       "Hash[Integer, 0]"            => 'Hash-Type[] arguments must be types. Got Fixnum',
       "Array[Integer,1,2,3]"        => 'Array-Type[] accepts 1 to 3 arguments. Got 4',
       "Array[Integer,String]"       => "A Type's size constraint arguments must be a single Integer type, or 1-2 integers (or default). Got a String-Type",
       "Hash[Integer,String, 1,2,3]" => 'Hash-Type[] accepts 1 to 4 arguments. Got 5',
       "'abc'[x]"                    => "The value 'x' cannot be converted to Numeric",
       "'abc'[1.0]"                  => "A String[] cannot use Float where Integer is expected",
       "'abc'[1,2,3]"                => "String supports [] with one or two arguments. Got 3",
       "Resource[0]"                 => 'First argument to Resource[] must be a resource type or a String. Got Fixnum',
       "Resource[a, 0]"              => 'Error creating type specialization of a Resource-Type, Cannot use Fixnum where String is expected',
       "File[0]"                     => 'Error creating type specialization of a File-Type, Cannot use Fixnum where String is expected',
       "String[a]"                   => "A Type's size constraint arguments must be a single Integer type, or 1-2 integers (or default). Got a String",
       "Pattern[0]"                  => 'Error creating type specialization of a Pattern-Type, Cannot use Fixnum where String or Regexp or Pattern-Type or Regexp-Type is expected',
       "Regexp[0]"                   => 'Error creating type specialization of a Regexp-Type, Cannot use Fixnum where String or Regexp is expected',
       "Regexp[a,b]"                 => 'A Regexp-Type[] accepts 1 argument. Got 2',
       "true[0]"                     => "Operator '[]' is not applicable to a Boolean",
       "1[0]"                        => "Operator '[]' is not applicable to an Integer",
       "3.14[0]"                     => "Operator '[]' is not applicable to a Float",
       "/.*/[0]"                     => "Operator '[]' is not applicable to a Regexp",
       "[1][a]"                      => "The value 'a' cannot be converted to Numeric",
       "[1][0.0]"                    => "An Array[] cannot use Float where Integer is expected",
       "[1]['0.0']"                  => "An Array[] cannot use Float where Integer is expected",
       "[1,2][1, 0.0]"               => "An Array[] cannot use Float where Integer is expected",
       "[1,2][1.0, -1]"              => "An Array[] cannot use Float where Integer is expected",
       "[1,2][1, -1.0]"              => "An Array[] cannot use Float where Integer is expected",
     }.each do |source, result|
       it "should parse and evaluate the expression '#{source}' to #{result}" do
         expect { parser.evaluate_string(scope, source, __FILE__)}.to raise_error(Regexp.new(Regexp.quote(result)))
       end
     end
 
     context "on catalog types" do
       it "[n] gets resource parameter [n]" do
         source = "notify { 'hello': message=>'yo'} Notify[hello][message]"
         parser.evaluate_string(scope, source, __FILE__).should == 'yo'
       end
 
       it "[n] gets class parameter [n]" do
         source = "class wonka($produces='chocolate'){ }
            include wonka
            Class[wonka][produces]"
 
         # This is more complicated since it needs to run like 3.x and do an import_ast
         adapted_parser = Puppet::Parser::E4ParserAdapter.new
         adapted_parser.file = __FILE__
         ast = adapted_parser.parse(source)
         scope.known_resource_types.import_ast(ast, '')
         ast.code.safeevaluate(scope).should == 'chocolate'
       end
 
       # Resource default and override expressions and resource parameter access with []
       {
         "notify { id: message=>explicit} Notify[id][message]"                   => "explicit",
         "Notify { message=>by_default} notify {foo:} Notify[foo][message]"      => "by_default",
         "notify {foo:} Notify[foo]{message =>by_override} Notify[foo][message]" => "by_override",
       }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
       # Resource default and override expressions and resource parameter access error conditions
       {
         "notify { xid: message=>explicit} Notify[id][message]"  => /Resource not found/,
         "notify { id: message=>explicit} Notify[id][mustard]"   => /does not have a parameter called 'mustard'/,
       }.each do |source, result|
         it "should parse '#{source}' and raise error matching #{result}" do
           expect { parser.evaluate_string(scope, source, __FILE__)}.to raise_error(result)
         end
       end
 
       context 'with errors' do
         { "Class['fail-whale']" => /Illegal name/,
           "Class[0]"            => /An Integer cannot be used where a String is expected/,
           "Class[/.*/]"         => /A Regexp cannot be used where a String is expected/,
           "Class[4.1415]"       => /A Float cannot be used where a String is expected/,
           "Class[Integer]"      => /An Integer-Type cannot be used where a String is expected/,
           "Class[File['tmp']]"   => /A File\['tmp'\] Resource-Reference cannot be used where a String is expected/,
         }.each do | source, error_pattern|
           it "an error is flagged for '#{source}'" do
             expect { parser.evaluate_string(scope, source, __FILE__)}.to raise_error(error_pattern)
           end
         end
       end
     end
   # end [] operations
   end
 
   context "When the evaluator performs boolean operations" do
     {
       "true and true"   => true,
       "false and true"  => false,
       "true and false"  => false,
       "false and false" => false,
       "true or true"    => true,
       "false or true"   => true,
       "true or false"   => true,
       "false or false"  => false,
       "! true"          => false,
       "!! true"         => true,
       "!! false"        => false,
       "! 'x'"           => false,
       "! ''"            => true,
       "! undef"         => true,
       "! [a]"           => false,
       "! []"            => false,
       "! {a=>1}"        => false,
       "! {}"            => false,
       "true and false and '0xwtf' + 1"  => false,
       "false or true  or '0xwtf' + 1"  => true,
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
     {
       "false || false || '0xwtf' + 1"   => :error,
     }.each do |source, result|
         it "should parse and raise error for '#{source}'" do
           expect { parser.evaluate_string(scope, source, __FILE__) }.to raise_error(Puppet::ParseError)
         end
       end
   end
 
   context "When evaluator performs operations on literal undef" do
     it "computes non existing hash lookup as undef" do
       parser.evaluate_string(scope, "{a => 1}[b] == undef", __FILE__).should == true
       parser.evaluate_string(scope, "undef == {a => 1}[b]", __FILE__).should == true
     end
   end
 
   context "When evaluator performs calls" do
     let(:populate) do
       parser.evaluate_string(scope, "$a = 10 $b = [1,2,3]")
     end
 
     {
       'sprintf( "x%iy", $a )'                 => "x10y",
       '"x%iy".sprintf( $a )'                  => "x10y",
       '$b.reduce |$memo,$x| { $memo + $x }'   => 6,
       'reduce($b) |$memo,$x| { $memo + $x }'  => 6,
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           populate
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
     {
       '"value is ${a*2} yo"'  => :error,
     }.each do |source, result|
         it "should parse and raise error for '#{source}'" do
           expect { parser.evaluate_string(scope, source, __FILE__) }.to raise_error(Puppet::ParseError)
         end
       end
   end
 
   context "When evaluator performs string interpolation" do
     let(:populate) do
       parser.evaluate_string(scope, "$a = 10 $b = [1,2,3]")
     end
 
     {
       '"value is $a yo"'                      => "value is 10 yo",
       '"value is \$a yo"'                     => "value is $a yo",
       '"value is ${a} yo"'                    => "value is 10 yo",
       '"value is \${a} yo"'                   => "value is ${a} yo",
       '"value is ${$a} yo"'                   => "value is 10 yo",
       '"value is ${$a*2} yo"'                 => "value is 20 yo",
       '"value is ${sprintf("x%iy",$a)} yo"'   => "value is x10y yo",
       '"value is ${"x%iy".sprintf($a)} yo"'   => "value is x10y yo",
       '"value is ${[1,2,3]} yo"'              => "value is [1, 2, 3] yo",
       '"value is ${/.*/} yo"'                 => "value is /.*/ yo",
       '$x = undef "value is $x yo"'           => "value is  yo",
       '$x = default "value is $x yo"'         => "value is default yo",
       '$x = Array[Integer] "value is $x yo"'  => "value is Array[Integer] yo",
       '"value is ${Array[Integer]} yo"'       => "value is Array[Integer] yo",
     }.each do |source, result|
         it "should parse and evaluate the expression '#{source}' to #{result}" do
           populate
           parser.evaluate_string(scope, source, __FILE__).should == result
         end
       end
 
     it "should parse and evaluate an interpolation of a hash" do
       source = '"value is ${{a=>1,b=>2}} yo"'
       # This test requires testing against two options because a hash to string
       # produces a result that is unordered
       hashstr = {'a' => 1, 'b' => 2}.to_s
       alt_results = ["value is {a => 1, b => 2} yo", "value is {b => 2, a => 1} yo" ]
       populate
       parse_result = parser.evaluate_string(scope, source, __FILE__)
       alt_results.include?(parse_result).should == true
     end
 
     {
       '"value is ${a*2} yo"'  => :error,
     }.each do |source, result|
         it "should parse and raise error for '#{source}'" do
           expect { parser.evaluate_string(scope, source, __FILE__) }.to raise_error(Puppet::ParseError)
         end
       end
   end
 
   context "When evaluating variables" do
     context "that are non existing an error is raised for" do
       it "unqualified variable" do
         expect { parser.evaluate_string(scope, "$quantum_gravity", __FILE__) }.to raise_error(/Unknown variable/)
       end
 
       it "qualified variable" do
         expect { parser.evaluate_string(scope, "$quantum_gravity::graviton", __FILE__) }.to raise_error(/Unknown variable/)
       end
     end
 
     it "a lex error should be raised for '$foo::::bar'" do
       expect { parser.evaluate_string(scope, "$foo::::bar") }.to raise_error(Puppet::LexError, /Illegal fully qualified name at line 1:7/)
     end
 
     { '$a = $0'   => nil,
       '$a = $1'   => nil,
     }.each do |source, value|
       it "it is ok to reference numeric unassigned variables '#{source}'" do
         parser.evaluate_string(scope, source, __FILE__).should == value
       end
     end
 
     { '$00 = 0'   => /must be a decimal value/,
       '$0xf = 0'  => /must be a decimal value/,
       '$0777 = 0' => /must be a decimal value/,
       '$123a = 0' => /must be a decimal value/,
     }.each do |source, error_pattern|
       it "should raise an error for '#{source}'" do
         expect { parser.evaluate_string(scope, source, __FILE__) }.to raise_error(error_pattern)
       end
     end
+
+    context "an initial underscore in the last segment of a var name is allowed" do
+      { '$_a  = 1'   => 1,
+        '$__a = 1'   => 1,
+      }.each do |source, value|
+        it "as in this example '#{source}'" do
+          parser.evaluate_string(scope, source, __FILE__).should == value
+        end
+      end
+    end
   end
 
   context "When evaluating relationships" do
     it 'should form a relation with File[a] -> File[b]' do
       source = "File[a] -> File[b]"
       parser.evaluate_string(scope, source, __FILE__)
       scope.compiler.should have_relationship(['File', 'a', '->', 'File', 'b'])
     end
 
     it 'should form a relation with resource -> resource' do
       source = "notify{a:} -> notify{b:}"
       parser.evaluate_string(scope, source, __FILE__)
       scope.compiler.should have_relationship(['Notify', 'a', '->', 'Notify', 'b'])
     end
 
     it 'should form a relation with [File[a], File[b]] -> [File[x], File[y]]' do
       source = "[File[a], File[b]] -> [File[x], File[y]]"
       parser.evaluate_string(scope, source, __FILE__)
       scope.compiler.should have_relationship(['File', 'a', '->', 'File', 'x'])
       scope.compiler.should have_relationship(['File', 'b', '->', 'File', 'x'])
       scope.compiler.should have_relationship(['File', 'a', '->', 'File', 'y'])
       scope.compiler.should have_relationship(['File', 'b', '->', 'File', 'y'])
     end
 
     it 'should tolerate (eliminate) duplicates in operands' do
       source = "[File[a], File[a]] -> File[x]"
       parser.evaluate_string(scope, source, __FILE__)
       scope.compiler.should have_relationship(['File', 'a', '->', 'File', 'x'])
       scope.compiler.relationships.size.should == 1
     end
 
     it 'should form a relation with <-' do
       source = "File[a] <- File[b]"
       parser.evaluate_string(scope, source, __FILE__)
       scope.compiler.should have_relationship(['File', 'b', '->', 'File', 'a'])
     end
 
     it 'should form a relation with <-' do
       source = "File[a] <~ File[b]"
       parser.evaluate_string(scope, source, __FILE__)
       scope.compiler.should have_relationship(['File', 'b', '~>', 'File', 'a'])
     end
   end
 
   context "Detailed Error messages are reported" do
     it 'for illegal type references' do
       source = '1+1 { "title": }'
       # Error references position 5 at the opening '{'
       # Set file to nil to make it easier to match with line number (no file name in output)
       expect { parser.parse_string(source, nil) }.to raise_error(/Expression is not valid as a resource.*line 1:5/)
     end
 
     it 'for non r-value producing <| |>' do
       expect { parser.parse_string("$a = File <| |>", nil) }.to raise_error(/A Virtual Query does not produce a value at line 1:6/)
     end
 
     it 'for non r-value producing <<| |>>' do
       expect { parser.parse_string("$a = File <<| |>>", nil) }.to raise_error(/An Exported Query does not produce a value at line 1:6/)
     end
 
     it 'for non r-value producing define' do
       Puppet.expects(:err).with("Invalid use of expression. A 'define' expression does not produce a value at line 1:6")
       Puppet.expects(:err).with("Classes, definitions, and nodes may only appear at toplevel or inside other classes at line 1:6")
       expect { parser.parse_string("$a = define foo { }", nil) }.to raise_error(/2 errors/)
     end
 
     it 'for non r-value producing class' do
       Puppet.expects(:err).with("Invalid use of expression. A Host Class Definition does not produce a value at line 1:6")
       Puppet.expects(:err).with("Classes, definitions, and nodes may only appear at toplevel or inside other classes at line 1:6")
       expect { parser.parse_string("$a = class foo { }", nil) }.to raise_error(/2 errors/)
     end
 
     it 'for unclosed quote with indication of start position of string' do
       source = <<-SOURCE.gsub(/^ {6}/,'')
       $a = "xx
       yyy
       SOURCE
       # first char after opening " reported as being in error.
       expect { parser.parse_string(source) }.to raise_error(/Unclosed quote after '"' followed by 'xx\\nyy\.\.\.' at line 1:7/)
     end
 
     it 'for multiple errors with a summary exception' do
       Puppet.expects(:err).with("Invalid use of expression. A Node Definition does not produce a value at line 1:6")
       Puppet.expects(:err).with("Classes, definitions, and nodes may only appear at toplevel or inside other classes at line 1:6")
       expect { parser.parse_string("$a = node x { }",nil) }.to raise_error(/2 errors/)
     end
 
     it 'for a bad hostname' do
       expect {
         parser.parse_string("node 'macbook+owned+by+name' { }", nil)
       }.to raise_error(/The hostname 'macbook\+owned\+by\+name' contains illegal characters.*at line 1:6/)
     end
 
     it 'for a hostname with interpolation' do
       source = <<-SOURCE.gsub(/^ {6}/,'')
       $name = 'fred'
       node "macbook-owned-by$name" { }
       SOURCE
       expect {
         parser.parse_string(source, nil)
       }.to raise_error(/An interpolated expression is not allowed in a hostname of a node at line 2:23/)
     end
 
   end
 
   matcher :have_relationship do |expected|
     calc = Puppet::Pops::Types::TypeCalculator.new
 
     match do |compiler|
       op_name = {'->' => :relationship, '~>' => :subscription}
       compiler.relationships.any? do | relation |
         relation.source.type == expected[0] &&
         relation.source.title == expected[1] &&
         relation.type == op_name[expected[2]] &&
         relation.target.type == expected[3] &&
         relation.target.title == expected[4]
       end
     end
 
     failure_message_for_should do |actual|
       "Relationship #{expected[0]}[#{expected[1]}] #{expected[2]} #{expected[3]}[#{expected[4]}] but was unknown to compiler"
     end
   end
 
 end