[CHEF-3783] Make deprecated constants available

* Make deprecated constants in Chef::Mixin available by loading the
  relevant files from the chef/dsl files that replace them.
* Add deprecation warnings via const_missing hook.

12 files changed, 110 insertions, 9 deletions

diff --git a/lib/chef/dsl/data_query.rb b/lib/chef/dsl/data_query.rb
index ef5b490020..65e7b185a7 100644
--- a/lib/chef/dsl/data_query.rb
+++ b/lib/chef/dsl/data_query.rb
@@ -64,3 +64,8 @@ class Chef
     end
   end
 end
+
+# **DEPRECATED**
+# This used to be part of chef/mixin/language. Load the file to activate the deprecation code.
+require 'chef/mixin/language'
+
diff --git a/lib/chef/dsl/include_attribute.rb b/lib/chef/dsl/include_attribute.rb
index d8342af6a7..3a95ce7268 100644
--- a/lib/chef/dsl/include_attribute.rb
+++ b/lib/chef/dsl/include_attribute.rb
@@ -56,5 +56,8 @@ class Chef
   end
 end
 
+# **DEPRECATED**
+# This used to be part of chef/mixin/language_include_attribute. Load the file to activate the deprecation code.
+require 'chef/mixin/language_include_attribute'
 
 
diff --git a/lib/chef/dsl/include_recipe.rb b/lib/chef/dsl/include_recipe.rb
index 8cbee7a733..b4d076da10 100644
--- a/lib/chef/dsl/include_recipe.rb
+++ b/lib/chef/dsl/include_recipe.rb
@@ -39,4 +39,7 @@ class Chef
   end
 end
 
+# **DEPRECATED**
+# This used to be part of chef/mixin/language_include_recipe. Load the file to activate the deprecation code.
+require 'chef/mixin/language_include_recipe'
 
diff --git a/lib/chef/dsl/platform_introspection.rb b/lib/chef/dsl/platform_introspection.rb
index 3328bb5c9a..33aa451f30 100644
--- a/lib/chef/dsl/platform_introspection.rb
+++ b/lib/chef/dsl/platform_introspection.rb
@@ -211,3 +211,8 @@ class Chef
     end
   end
 end
+
+# **DEPRECATED**
+# This used to be part of chef/mixin/language. Load the file to activate the deprecation code.
+require 'chef/mixin/language'
+
diff --git a/lib/chef/dsl/recipe.rb b/lib/chef/dsl/recipe.rb
index 88006aced3..f3507a8031 100644
--- a/lib/chef/dsl/recipe.rb
+++ b/lib/chef/dsl/recipe.rb
@@ -20,7 +20,6 @@
 require 'chef/resource'
 require 'chef/resource_platform_map'
 require 'chef/mixin/convert_to_class_name'
-require 'chef/mixin/language'
 
 class Chef
   module DSL
@@ -82,3 +81,7 @@ class Chef
     end
   end
 end
+
+# **DEPRECATED**
+# This used to be part of chef/mixin/recipe_definition_dsl_core. Load the file to activate the deprecation code.
+require 'chef/mixin/recipe_definition_dsl_core'
diff --git a/lib/chef/mixin/deprecation.rb b/lib/chef/mixin/deprecation.rb
index cc85c4e976..489f27c339 100644
--- a/lib/chef/mixin/deprecation.rb
+++ b/lib/chef/mixin/deprecation.rb
@@ -18,7 +18,42 @@
 
 class Chef
   module Mixin
+
+
+      def self.deprecated_constants
+        @deprecated_constants ||= {}
+      end
+
+      # Add a deprecated constant to the Chef::Mixin namespace.
+      # === Arguments
+      # * name: the constant name, as a relative symbol.
+      # * replacement: the constant to return instead.
+      # * message: A message telling the user what to do instead.
+      # === Example:
+      #   deprecate_constant(:RecipeDefinitionDSLCore, Chef::DSL::Recipe, <<-EOM)
+      #     Chef::Mixin::RecipeDefinitionDSLCore is deprecated, use Chef::DSL::Recipe instead.
+      #   EOM
+      def self.deprecate_constant(name, replacement, message)
+        deprecated_constants[name] = {:replacement => replacement, :message => message}
+      end
+
+      # Const missing hook to look up deprecated constants defined with
+      # deprecate_constant. Emits a warning to the logger and returns the
+      # replacement constant. Will call super, most likely causing an exception
+      # for the missing constant, if +name+ is not found in the
+      # deprecated_constants collection.
+      def self.const_missing(name)
+        if new_const = deprecated_constants[name]
+          Chef::Log.warn(new_const[:message])
+          Chef::Log.warn("Called from: \n#{caller[0...3].map {|l| "\t#{l}"}.join("\n")}")
+          new_const[:replacement]
+        else
+          super
+        end
+      end
+
     module Deprecation
+
       class DeprecatedObjectProxyBase
         KEEPERS = %w{__id__ __send__ instance_eval == equal? initialize object_id}
         instance_methods.each { |method_name| undef_method(method_name) unless KEEPERS.include?(method_name.to_s)}
diff --git a/lib/chef/mixin/language.rb b/lib/chef/mixin/language.rb
index 3aa6a6d800..48d5a8403a 100644
--- a/lib/chef/mixin/language.rb
+++ b/lib/chef/mixin/language.rb
@@ -22,15 +22,26 @@ require 'chef/dsl/data_query'
 class Chef
   module Mixin
 
-    # == [DEPRECATED] Chef::Mixin::Language
-    # This module is deprecated and remains only for backwards compatibility.
+    # == [DEPRECATED] Chef::Mixin::DeprecatedLanguageModule
+    # This module is a temporary replacement for the previous
+    # Chef::Mixin::Language. That module's functionality was split into two
+    # modules, Chef::DSL::PlatformIntrospection, and Chef::DSL::DataQuery.
     #
-    # See Chef::DSL::PlatformIntrospection and Chef::DSL::DataQuery
-    module Language
+    # This module includes both PlatformIntrospection and DataQuery to provide
+    # the same interfaces and behavior as the prior Mixin::Language.
+    #
+    # This module is loaded via const_missing hook when Chef::Mixin::Language
+    # is accessed. See chef/mixin/deprecation for details.
+    module DeprecatedLanguageModule
 
       include Chef::DSL::PlatformIntrospection
       include Chef::DSL::DataQuery
 
     end
+
+    deprecate_constant(:Language, DeprecatedLanguageModule, <<-EOM)
+Chef::Mixin::Language is deprecated. Use either (or both)
+Chef::DSL::PlatformIntrospection or Chef::DSL::DataQuery instead.
+EOM
   end
 end
diff --git a/lib/chef/mixin/language_include_attribute.rb b/lib/chef/mixin/language_include_attribute.rb
index 283773b25d..ab21b50408 100644
--- a/lib/chef/mixin/language_include_attribute.rb
+++ b/lib/chef/mixin/language_include_attribute.rb
@@ -23,7 +23,12 @@ class Chef
 
     # DEPRECATED: This is just here for compatibility, use
     # Chef::DSL::IncludeAttribute instead.
-    LanguageIncludeAttribute = Chef::DSL::IncludeAttribute
+
+    deprecate_constant(:LanguageIncludeAttribute, Chef::DSL::IncludeAttribute, <<-EOM)
+Chef::Mixin::LanguageIncludeAttribute is deprecated. Use
+Chef::DSL::IncludeAttribute instead.
+EOM
+
   end
 end
 
diff --git a/lib/chef/mixin/language_include_recipe.rb b/lib/chef/mixin/language_include_recipe.rb
index 0566046560..ccbfb38c65 100644
--- a/lib/chef/mixin/language_include_recipe.rb
+++ b/lib/chef/mixin/language_include_recipe.rb
@@ -20,7 +20,12 @@ require 'chef/dsl/include_recipe'
 
 class Chef
   module Mixin
-    LanguageIncludeRecipe = Chef::DSL::IncludeRecipe
+
+    deprecate_constant(:LanguageIncludeRecipe, Chef::DSL::IncludeRecipe, <<-EOM)
+Chef::Mixin::LanguageIncludeRecipe is deprecated, use Chef::DSL::Recipe
+instead.
+EOM
+
   end
 end
 
diff --git a/lib/chef/mixin/recipe_definition_dsl_core.rb b/lib/chef/mixin/recipe_definition_dsl_core.rb
index ff422d892f..704ee162be 100644
--- a/lib/chef/mixin/recipe_definition_dsl_core.rb
+++ b/lib/chef/mixin/recipe_definition_dsl_core.rb
@@ -24,10 +24,12 @@
 # This constant (module name) will eventually be deprecated and then removed.
 ###
 
-require 'chef/dsl/recipe'
+require 'chef/mixin/deprecation'
 
 class Chef
   module Mixin
-    RecipeDefinitionDSLCore = Chef::DSL::Recipe
+    deprecate_constant(:RecipeDefinitionDSLCore, Chef::DSL::Recipe, <<-EOM)
+Chef::Mixin::RecipeDefinitionDSLCore is deprecated. Use Chef::DSL::Recipe instead.
+EOM
   end
 end
diff --git a/lib/chef/mixins.rb b/lib/chef/mixins.rb
index 557932c0e6..8fa9c699e6 100644
--- a/lib/chef/mixins.rb
+++ b/lib/chef/mixins.rb
@@ -12,3 +12,4 @@ require 'chef/mixin/path_sanity'
 require 'chef/mixin/template'
 require 'chef/mixin/securable'
 require 'chef/mixin/xml_escape'
+
diff --git a/spec/unit/mixin/deprecation_spec.rb b/spec/unit/mixin/deprecation_spec.rb
index 1b62dcd124..c3170007de 100644
--- a/spec/unit/mixin/deprecation_spec.rb
+++ b/spec/unit/mixin/deprecation_spec.rb
@@ -19,6 +19,29 @@
 require 'spec_helper'
 require 'chef/mixin/deprecation'
 
+describe Chef::Mixin do
+  describe "deprecating constants (Class/Module)" do
+    before do
+      Chef::Mixin.deprecate_constant(:DeprecatedClass, Chef::Node, "This is a test deprecation")
+      @log_io = StringIO.new
+      Chef::Log.init(@log_io)
+    end
+
+    it "has a list of deprecated constants" do
+      Chef::Mixin.deprecated_constants.should have_key(:DeprecatedClass)
+    end
+
+    it "returns the replacement when accessing the deprecated constant" do
+      Chef::Mixin::DeprecatedClass.should == Chef::Node
+    end
+
+    it "warns when accessing the deprecated constant" do
+      Chef::Mixin::DeprecatedClass
+      @log_io.string.should include("This is a test deprecation")
+    end
+  end
+end
+
 describe Chef::Mixin::Deprecation::DeprecatedInstanceVariable do
   before do
     Chef::Log.logger = Logger.new(StringIO.new)