Merge pull request #2386 from opscode/sersut/12-attr-port

Merge pull request #2097 from opscode/lcg/chef-12-attr

7 files changed, 540 insertions, 44 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a388733423..aed9f16163 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -146,6 +146,7 @@
 
 ### Chef Contributions
 
+* Added RFC-023 Chef 12 Attribute Changes (https://github.com/opscode/chef-rfc/blob/master/rfc023-chef-12-attributes-changes.md)
 * Added os/platform_family options to provides syntax on the Chef::Resource DSL
 * Added provides methods to the Chef::Provider DSL
 * Added supported?(resource, action) class method to all Providers for late-evaluation if a provider can handle a
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index 3541460625..924f189543 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -21,6 +21,14 @@ block to the `on_create` method; it is now configured by calling either
 
 # End-User Changes
 
+## Chef 12 Attribute Changes
+
+The Chef 12 Attribute RFC 23 (https://github.com/opscode/chef-rfc/blob/master/rfc023-chef-12-attributes-changes.md) has been merged into
+Chef.  This adds the ability to remove precedence levels (or all levels) of attributes in recipes code, or to
+force setting an attribute precedence level.  The major backwards incompatible change to call out in this RFC is that
+`node.force_default!` and `node.force_override!` have changed from accessors to setters, and any cookbook code that used these functions
+(extremely uncommon) simply needs to drop the exclamation point off of the method in order to use the accessor.
+
 ## Knife Prefers `config.rb` to `knife.rb`.
 
 Knife will now look for `config.rb` in preference to `knife.rb` for its
diff --git a/lib/chef/node.rb b/lib/chef/node.rb
index 5f788af4d4..dbb7852586 100644
--- a/lib/chef/node.rb
+++ b/lib/chef/node.rb
@@ -42,6 +42,8 @@ class Chef
     extend Forwardable
 
     def_delegators :attributes, :keys, :each_key, :each_value, :key?, :has_key?
+    def_delegators :attributes, :rm, :rm_default, :rm_normal, :rm_override
+    def_delegators :attributes, :default!, :normal!, :override!, :force_default!, :force_override!
 
     attr_accessor :recipe_list, :run_state, :override_runlist
 
@@ -146,13 +148,6 @@ class Chef
       attributes.default
     end
 
-    # Set a force default attribute. Intermediate mashes will be created by
-    # auto-vivify if necessary.
-    def default!
-      attributes.set_unless_value_present = false
-      attributes.default!
-    end
-
     # Set a default attribute of this node, auto-vivifying any mashes that are
     # missing, but if the final value already exists, don't set it
     def default_unless
@@ -167,13 +162,6 @@ class Chef
       attributes.override
     end
 
-    # Set a force override attribute. Intermediate mashes will be created by
-    # auto-vivify if needed.
-    def override!
-      attributes.set_unless_value_present = false
-      attributes.override!
-    end
-
     # Set an override attribute of this node, auto-vivifying any mashes that
     # are missing, but if the final value already exists, don't set it
     def override_unless
diff --git a/lib/chef/node/attribute.rb b/lib/chef/node/attribute.rb
index 66569cf0e1..3eb6449046 100644
--- a/lib/chef/node/attribute.rb
+++ b/lib/chef/node/attribute.rb
@@ -58,7 +58,6 @@ class Chef
         :@force_default
       ]
 
-
       OVERRIDE_COMPONENTS = [
         :@override,
         :@role_override,
@@ -146,7 +145,6 @@ class Chef
          METHOD_DEFN
        end
 
-
        # return the cookbook level default attribute component
        attr_reader :default
 
@@ -159,11 +157,6 @@ class Chef
        # return the force_default level attribute component
        attr_reader :force_default
 
-       # default! is the "advertised" method for force_default, but is
-       # implemented as an alias because instance variables can't (easily) have
-       # +!+ characters.
-       alias :default! :force_default
-
        # return the "normal" level attribute component
        attr_reader :normal
 
@@ -179,11 +172,6 @@ class Chef
        # return the force override level attribute component
        attr_reader :force_override
 
-       # +override!+ is the "advertised" method for +force_override+ but is
-       # implemented as an alias because instance variables can't easily have
-       # +!+ characters.
-       alias :override! :force_override
-
        # return the automatic level attribute component
        attr_reader :automatic
 
@@ -311,6 +299,100 @@ class Chef
          @automatic = VividMash.new(self, new_data)
        end
 
+       #
+       # Deleting attributes
+       #
+
+       # clears attributes from all precedence levels
+       def rm(*args)
+         # just easier to compute our retval, rather than collect+merge sub-retvals
+         ret = args.inject(merged_attributes) do |attr, arg|
+           if attr.nil? || !attr.respond_to?(:[])
+             nil
+           else
+             begin
+               attr[arg]
+             rescue TypeError
+               raise TypeError, "Wrong type in index of attribute (did you use a Hash index on an Array?)"
+             end
+           end
+         end
+         rm_default(*args)
+         rm_normal(*args)
+         rm_override(*args)
+         ret
+       end
+
+       # does <level>['foo']['bar'].delete('baz')
+       def remove_from_precedence_level(level, *args, key)
+         multimash = level.element(*args)
+         multimash.nil? ? nil : multimash.delete(key)
+       end
+
+       private :remove_from_precedence_level
+
+       # clears attributes from all default precedence levels
+       #
+       # equivalent to: force_default!['foo']['bar'].delete('baz')
+       def rm_default(*args)
+         reset
+         remove_from_precedence_level(force_default!(autovivify: false), *args)
+       end
+
+       # clears attributes from normal precedence
+       #
+       # equivalent to: normal!['foo']['bar'].delete('baz')
+       def rm_normal(*args)
+         reset
+         remove_from_precedence_level(normal!(autovivify: false), *args)
+       end
+
+       # clears attributes from all override precedence levels
+       #
+       # equivalent to: force_override!['foo']['bar'].delete('baz')
+       def rm_override(*args)
+         reset
+         remove_from_precedence_level(force_override!(autovivify: false), *args)
+       end
+
+       #
+       # Replacing attributes without merging
+       #
+
+       # sets default attributes without merging
+       def default!(opts={})
+         reset
+         MultiMash.new(self, @default, [], opts)
+       end
+
+       # sets normal attributes without merging
+       def normal!(opts={})
+         reset
+         MultiMash.new(self, @normal, [], opts)
+       end
+
+       # sets override attributes without merging
+       def override!(opts={})
+         reset
+         MultiMash.new(self, @override, [], opts)
+       end
+
+       # clears from all default precedence levels and then sets force_default
+       def force_default!(opts={})
+         reset
+         MultiMash.new(self, @force_default, [@default, @env_default, @role_default], opts)
+       end
+
+       # clears from all override precedence levels and then sets force_override
+       def force_override!(opts={})
+         reset
+         MultiMash.new(self, @force_override, [@override, @env_override, @role_override], opts)
+       end
+
+       #
+       # Accessing merged attributes
+       #
+
        def merged_attributes
          @merged_attributes ||= begin
                                   components = [merge_defaults, @normal, merge_overrides, @automatic]
@@ -391,7 +473,6 @@ class Chef
          end
        end
 
-
     end
 
   end
diff --git a/lib/chef/node/attribute_collections.rb b/lib/chef/node/attribute_collections.rb
index f09b02b106..c8bc618762 100644
--- a/lib/chef/node/attribute_collections.rb
+++ b/lib/chef/node/attribute_collections.rb
@@ -209,5 +209,117 @@ class Chef
 
     end
 
+    # == MultiMash
+    # This is a Hash-like object that contains multiple VividMashes in it.  Its
+    # purpose is so that the user can descend into the mash and delete a subtree
+    # from all of the Mash objects (used to delete all values in a subtree from
+    # default, force_default, role_default and env_default at the same time).  The
+    # assignment operator strictly does assignment (does no merging) and works
+    # by deleting the subtree and then assigning to the last mash which passed in
+    # the initializer.
+    #
+    # A lot of the complexity of this class comes from the fact that at any key
+    # value some or all of the mashes may walk off their ends and become nil or
+    # true or something.  The schema may change so that one precidence leve may
+    # be 'true' object and another may be a VividMash.  It is also possible that
+    # one or many of them may transition from VividMashes to Hashes or Arrays.
+    #
+    # It also supports the case where you may be deleting a key using node.rm
+    # in which case if intermediate keys all walk off into nil then you don't want
+    # to be autovivifying keys as you go.  On the other hand you may be using
+    # node.force_default! in which case you'll wind up with a []= operator at the
+    # end and you want autovivification, so we conditionally have to support either
+    # operation.
+    #
+    # @todo: can we have an autovivify class that decorates a class that doesn't
+    # autovivify or something so that the code is less awful?
+    #
+    class MultiMash
+      attr_reader :root
+      attr_reader :mashes
+      attr_reader :opts
+      attr_reader :primary_mash
+
+      # Initialize with an array of mashes.  For the delete return value to work
+      # properly the mashes must come from the same attribute level (i.e. all
+      # override or all default, but not a mix of both).
+      def initialize(root, primary_mash, mashes, opts={})
+        @root = root
+        @primary_mash = primary_mash
+        @mashes = mashes
+        @opts = opts
+        @opts[:autovivify] = true if @opts[:autovivify].nil?
+      end
+
+      def [](key)
+        # handle the secondary mashes
+        new_mashes = []
+        mashes.each do |mash|
+          new_mash = safe_evalute_key(mash, key)
+          # secondary mashes never autovivify so once they fall into nil, we just stop tracking them
+          new_mashes.push(new_mash) unless new_mash.nil?
+        end
+
+        new_primary_mash = safe_evalute_key(primary_mash, key)
+
+        if new_primary_mash.nil? && @opts[:autovivify]
+          primary_mash[key] = VividMash.new(root)
+          new_primary_mash = primary_mash[key]
+        end
+
+        MultiMash.new(root, new_primary_mash, new_mashes, opts)
+      end
+
+      def []=(key, value)
+        if primary_mash.nil?
+          # This theoretically should never happen since node#force_default! setter methods will autovivify and
+          # node#rm methods do not end in #[]= operators.
+          raise TypeError, "No autovivification was specified initially on a method chain ending in assignment"
+        end
+        ret = delete(key)
+        primary_mash[key] = value
+        ret
+      end
+
+      # mash.element('foo', 'bar') is the same as mash['foo']['bar']
+      def element(key = nil, *subkeys)
+        return self if key.nil?
+        submash = self[key]
+        subkeys.empty? ? submash : submash.element(*subkeys)
+      end
+
+      def delete(key)
+        # the return value is a deep merge which is correct semantics when
+        # merging between attributes on the same level (this would be incorrect
+        # if passed both override and default attributes which would need hash_only
+        # merging).
+        ret = mashes.inject(Mash.new) do |merged, mash|
+          Chef::Mixin::DeepMerge.merge(merged, mash)
+        end
+        ret = Chef::Mixin::DeepMerge.merge(ret, primary_mash)
+        mashes.each do |mash|
+          mash.delete(key) if mash.respond_to?(:delete)
+        end
+        primary_mash.delete(key) if primary_mash.respond_to?(:delete)
+        ret[key]
+      end
+
+      private
+
+      def safe_evalute_key(mash, key)
+        if mash.respond_to?(:[])
+          if mash.respond_to?(:has_key?)
+            if mash.has_key?(key)
+              return mash[key] if mash[key].respond_to?(:[])
+            end
+          elsif !mash[key].nil?
+            return mash[key] if mash[key].respond_to?(:[])
+          end
+        end
+        return nil
+      end
+
+    end
+
   end
 end
diff --git a/spec/unit/node/attribute_spec.rb b/spec/unit/node/attribute_spec.rb
index 5325117d6c..3b3a81f3a6 100644
--- a/spec/unit/node/attribute_spec.rb
+++ b/spec/unit/node/attribute_spec.rb
@@ -285,7 +285,7 @@ describe Chef::Node::Attribute do
     end
 
     it "prefers 'forced default' over any other default" do
-      @attributes.default!["default"] = "force default"
+      @attributes.force_default["default"] = "force default"
       @attributes.role_default["default"] = "role default"
       @attributes.env_default["default"] = "environment default"
       @attributes["default"].should == "force default"
@@ -307,7 +307,7 @@ describe Chef::Node::Attribute do
     end
 
     it "prefers 'forced overrides' over role or cookbook overrides" do
-      @attributes.override!["override"] = "force override"
+      @attributes.force_override["override"] = "force override"
       @attributes.env_override["override"] = "environment override"
       @attributes.role_override["override"] = "role override"
       @attributes["override"].should == "force override"
@@ -939,7 +939,6 @@ describe Chef::Node::Attribute do
 
   end
 
-
   describe "values" do
     before do
       @attributes = Chef::Node::Attribute.new(
@@ -1185,4 +1184,3 @@ describe Chef::Node::Attribute do
   end
 
 end
-
diff --git a/spec/unit/node_spec.rb b/spec/unit/node_spec.rb
index da7a67aec1..695da8d671 100644
--- a/spec/unit/node_spec.rb
+++ b/spec/unit/node_spec.rb
@@ -247,13 +247,6 @@ describe Chef::Node do
         node.default.fuu.bahrr.baz = "qux"
         node.fuu.bahrr.baz.should == "qux"
       end
-
-      it "accesses force defaults via default!" do
-        node.default![:foo] = "wet bar"
-        node.default[:foo] = "bar"
-        node[:foo].should == "wet bar"
-      end
-
     end
 
     describe "override attributes" do
@@ -292,13 +285,330 @@ describe Chef::Node do
         node.override.fuu.bahrr.baz = "qux"
         node.fuu.bahrr.baz.should == "qux"
       end
+    end
+
+    describe "globally deleting attributes" do
+      context "with hash values" do
+        before do
+          node.role_default["mysql"]["server"]["port"] = 1234
+          node.normal["mysql"]["server"]["port"] = 2345
+          node.override["mysql"]["server"]["port"] = 3456
+        end
+
+        it "deletes all the values and returns the value with the highest precidence" do
+          expect( node.rm("mysql", "server", "port") ).to eql(3456)
+          expect( node["mysql"]["server"]["port"] ).to be_nil
+          expect( node["mysql"]["server"] ).to eql({})
+        end
+
+        it "deletes nested things correctly" do
+          node.default["mysql"]["client"]["client_setting"] = "foo"
+          expect( node.rm("mysql", "server") ).to eql( {"port" => 3456} )
+          expect( node["mysql"] ).to eql( { "client" => { "client_setting" => "foo" } } )
+        end
+
+        it "returns nil if the node attribute does not exist" do
+          expect( node.rm("no", "such", "thing") ).to be_nil
+        end
 
-      it "sets force_overrides via override!" do
-        node.override![:foo] = "wet bar"
-        node.override[:foo] = "bar"
-        node[:foo].should == "wet bar"
+        it "can delete the entire tree" do
+          expect( node.rm("mysql") ).to eql({"server"=>{"port"=>3456}})
+        end
       end
 
+      context "when trying to delete through a thing that isn't an array-like or hash-like object" do
+        before do
+          node.default["mysql"] = true
+        end
+
+        it "returns nil when you're two levels deeper" do
+          expect( node.rm("mysql", "server", "port") ).to eql(nil)
+        end
+
+        it "returns nil when you're one level deeper" do
+          expect( node.rm("mysql", "server") ).to eql(nil)
+        end
+
+        it "correctly deletes at the top level" do
+          expect( node.rm("mysql") ).to eql(true)
+        end
+      end
+
+      context "with array indexes" do
+        before do
+          node.role_default["mysql"]["server"][0]["port"] = 1234
+          node.normal["mysql"]["server"][0]["port"] = 2345
+          node.override["mysql"]["server"][0]["port"] = 3456
+          node.override["mysql"]["server"][1]["port"] = 3456
+        end
+
+        it "deletes the array element" do
+          expect( node.rm("mysql", "server", 0, "port") ).to eql(3456)
+          expect( node["mysql"]["server"][0]["port"] ).to be_nil
+          expect( node["mysql"]["server"][1]["port"] ).to eql(3456)
+        end
+      end
+
+      context "with real arrays" do
+        before do
+          node.role_default["mysql"]["server"] = [ {
+            "port" => 1234,
+          } ]
+          node.normal["mysql"]["server"] = [ {
+            "port" => 2345,
+          } ]
+          node.override["mysql"]["server"] = [ {
+            "port" => 3456,
+          } ]
+        end
+
+        it "deletes the array element" do
+          expect( node.rm("mysql", "server", 0, "port") ).to eql(3456)
+          expect( node["mysql"]["server"][0]["port"] ).to be_nil
+        end
+
+        it "does not have a horrible error message when mistaking arrays for hashes" do
+          expect { node.rm("mysql", "server", "port") }.to raise_error(TypeError, "Wrong type in index of attribute (did you use a Hash index on an Array?)")
+        end
+      end
+    end
+
+    describe "granular deleting attributes" do
+      context "when only defaults exist" do
+        before do
+          node.role_default["mysql"]["server"]["port"] = 1234
+          node.default["mysql"]["server"]["port"] = 2345
+          node.force_default["mysql"]["server"]["port"] = 3456
+        end
+
+        it "returns the deleted values" do
+          expect( node.rm_default("mysql", "server", "port") ).to eql(3456)
+        end
+
+        it "returns nil for the combined attribues" do
+          expect( node.rm_default("mysql", "server", "port") ).to eql(3456)
+          expect( node["mysql"]["server"]["port"] ).to eql(nil)
+        end
+
+        it "returns an empty hash for the default attrs" do
+          expect( node.rm_default("mysql", "server", "port") ).to eql(3456)
+          # this auto-vivifies, should it?
+          expect( node.default_attrs["mysql"]["server"]["port"] ).to eql({})
+        end
+
+        it "returns an empty hash after the last key is deleted" do
+          expect( node.rm_default("mysql", "server", "port") ).to eql(3456)
+          expect( node["mysql"]["server"] ).to eql({})
+        end
+      end
+
+      context "when trying to delete through a thing that isn't an array-like or hash-like object" do
+        before do
+          node.default["mysql"] = true
+        end
+
+        it "returns nil when you're two levels deeper" do
+          expect( node.rm_default("mysql", "server", "port") ).to eql(nil)
+        end
+
+        it "returns nil when you're one level deeper" do
+          expect( node.rm_default("mysql", "server") ).to eql(nil)
+        end
+
+        it "correctly deletes at the top level" do
+          expect( node.rm_default("mysql") ).to eql(true)
+        end
+      end
+
+      context "when a higher precedence exists" do
+        before do
+          node.role_default["mysql"]["server"]["port"] = 1234
+          node.default["mysql"]["server"]["port"] = 2345
+          node.force_default["mysql"]["server"]["port"] = 3456
+
+          node.override["mysql"]["server"]["port"] = 9999
+        end
+
+        it "returns the deleted values" do
+          expect( node.rm_default("mysql", "server", "port") ).to eql(3456)
+        end
+
+        it "returns the higher precedence values after the delete" do
+          expect( node.rm_default("mysql", "server", "port") ).to eql(3456)
+          expect( node["mysql"]["server"]["port"] ).to eql(9999)
+        end
+
+        it "returns an empty has for the default attrs" do
+          expect( node.rm_default("mysql", "server", "port") ).to eql(3456)
+          # this auto-vivifies, should it?
+          expect( node.default_attrs["mysql"]["server"]["port"] ).to eql({})
+        end
+      end
+
+      context "when a lower precedence exists" do
+        before do
+          node.default["mysql"]["server"]["port"] = 2345
+          node.override["mysql"]["server"]["port"] = 9999
+          node.role_override["mysql"]["server"]["port"] = 9876
+          node.force_override["mysql"]["server"]["port"] = 6669
+        end
+
+        it "returns the deleted values" do
+          expect( node.rm_override("mysql", "server", "port") ).to eql(6669)
+        end
+
+        it "returns the lower precedence levels after the delete" do
+          expect( node.rm_override("mysql", "server", "port") ).to eql(6669)
+          expect( node["mysql"]["server"]["port"] ).to eql(2345)
+        end
+
+        it "returns an empty has for the override attrs" do
+          expect( node.rm_override("mysql", "server", "port") ).to eql(6669)
+          # this auto-vivifies, should it?
+          expect( node.override_attrs["mysql"]["server"]["port"] ).to eql({})
+        end
+      end
+
+      it "rm_default returns nil on deleting non-existent values" do
+        expect( node.rm_default("no", "such", "thing") ).to be_nil
+      end
+
+      it "rm_normal returns nil on deleting non-existent values" do
+        expect( node.rm_normal("no", "such", "thing") ).to be_nil
+      end
+
+      it "rm_override returns nil on deleting non-existent values" do
+        expect( node.rm_override("no", "such", "thing") ).to be_nil
+      end
+    end
+
+    describe "granular replacing attributes" do
+      it "removes everything at the level of the last key" do
+        node.default["mysql"]["server"]["port"] = 2345
+
+        node.default!["mysql"]["server"] = { "data_dir" => "/my_raid_volume/lib/mysql" }
+
+        expect( node["mysql"]["server"] ).to eql({ "data_dir" => "/my_raid_volume/lib/mysql" })
+      end
+
+      it "replaces a value at the cookbook sub-level of the atributes only" do
+        node.default["mysql"]["server"]["port"] = 2345
+        node.default["mysql"]["server"]["service_name"] = "fancypants-sql"
+        node.role_default["mysql"]["server"]["port"] = 1234
+        node.force_default["mysql"]["server"]["port"] = 3456
+
+        node.default!["mysql"]["server"] = { "data_dir" => "/my_raid_volume/lib/mysql" }
+
+        expect( node["mysql"]["server"]["port"] ).to eql(3456)
+        expect( node["mysql"]["server"]["service_name"] ).to be_nil
+        expect( node["mysql"]["server"]["data_dir"] ).to eql("/my_raid_volume/lib/mysql")
+        expect( node["mysql"]["server"] ).to eql({ "port" => 3456, "data_dir" => "/my_raid_volume/lib/mysql" })
+      end
+
+      it "higher precedence values aren't removed" do
+        node.role_default["mysql"]["server"]["port"] = 1234
+        node.default["mysql"]["server"]["port"] = 2345
+        node.force_default["mysql"]["server"]["port"] = 3456
+        node.override["mysql"]["server"]["service_name"] = "fancypants-sql"
+
+        node.default!["mysql"]["server"] = { "data_dir" => "/my_raid_volume/lib/mysql" }
+
+        expect( node["mysql"]["server"]["port"] ).to eql(3456)
+        expect( node["mysql"]["server"]["data_dir"] ).to eql("/my_raid_volume/lib/mysql")
+        expect( node["mysql"]["server"] ).to eql({ "service_name" => "fancypants-sql", "port" => 3456, "data_dir" => "/my_raid_volume/lib/mysql" })
+      end
+    end
+
+    describe "granular force replacing attributes" do
+      it "removes everything at the level of the last key" do
+        node.force_default["mysql"]["server"]["port"] = 2345
+
+        node.force_default!["mysql"]["server"] = {
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        }
+
+        expect( node["mysql"]["server"] ).to eql({
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        })
+      end
+
+      it "removes all values from the precedence level when setting" do
+        node.role_default["mysql"]["server"]["port"] = 1234
+        node.default["mysql"]["server"]["port"] = 2345
+        node.force_default["mysql"]["server"]["port"] = 3456
+
+        node.force_default!["mysql"]["server"] = {
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        }
+
+        expect( node["mysql"]["server"]["port"] ).to be_nil
+        expect( node["mysql"]["server"]["data_dir"] ).to eql("/my_raid_volume/lib/mysql")
+        expect( node["mysql"]["server"] ).to eql({
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        })
+      end
+
+      it "higher precedence levels are not removed" do
+        node.role_default["mysql"]["server"]["port"] = 1234
+        node.default["mysql"]["server"]["port"] = 2345
+        node.force_default["mysql"]["server"]["port"] = 3456
+        node.override["mysql"]["server"]["service_name"] = "fancypants-sql"
+
+        node.force_default!["mysql"]["server"] = {
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        }
+
+        expect( node["mysql"]["server"]["port"] ).to be_nil
+        expect( node["mysql"]["server"]["data_dir"] ).to eql("/my_raid_volume/lib/mysql")
+        expect( node["mysql"]["server"] ).to eql({
+          "service_name" => "fancypants-sql",
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        })
+      end
+
+      it "will autovivify" do
+        node.force_default!["mysql"]["server"] = {
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        }
+        expect( node["mysql"]["server"]["data_dir"] ).to eql("/my_raid_volume/lib/mysql")
+      end
+
+      it "lower precedence levels aren't removed" do
+        node.role_override["mysql"]["server"]["port"] = 1234
+        node.override["mysql"]["server"]["port"] = 2345
+        node.force_override["mysql"]["server"]["port"] = 3456
+        node.default["mysql"]["server"]["service_name"] = "fancypants-sql"
+
+        node.force_override!["mysql"]["server"] = {
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        }
+
+        expect( node["mysql"]["server"]["port"] ).to be_nil
+        expect( node["mysql"]["server"]["data_dir"] ).to eql("/my_raid_volume/lib/mysql")
+        expect( node["mysql"]["server"] ).to eql({
+          "service_name" => "fancypants-sql",
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        })
+      end
+
+      it "when overwriting a non-hash/array" do
+        node.override["mysql"] = false
+        node.force_override["mysql"] = true
+        node.force_override!["mysql"]["server"] = {
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        }
+        expect( node["mysql"]["server"]["data_dir"] ).to eql("/my_raid_volume/lib/mysql")
+      end
+
+      it "when overwriting an array with a hash" do
+        node.force_override["mysql"][0] = true
+        node.force_override!["mysql"]["server"] = {
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        }
+        expect( node["mysql"]["server"] ).to eql({
+          "data_dir" => "/my_raid_volume/lib/mysql",
+        })
+      end
     end
 
     it "should raise an ArgumentError if you ask for an attribute that doesn't exist via method_missing" do
@@ -536,7 +846,6 @@ describe Chef::Node do
       @expansion.default_attrs.replace({:default => "from role", :d_role => "role only"})
       @expansion.override_attrs.replace({:override => "from role", :o_role => "role only"})
 
-
       @environment = Chef::Environment.new
       @environment.default_attributes = {:default => "from env", :d_env => "env only" }
       @environment.override_attributes = {:override => "from env", :o_env => "env only"}
@@ -753,7 +1062,6 @@ describe Chef::Node do
       node_for_json["default"]["env default"].should == "env default"
     end
 
-
     it "should deserialize itself from json", :json => true do
       node.from_file(File.expand_path("nodes/test.example.com.rb", CHEF_SPEC_DATA))
       json = Chef::JSONCompat.to_json(node)