AMo #key is now #to_key and CI is probably happy

Obviously #key is a too common name to be included
in the AMo interface, #to_key fits better and also
relates nicely to #to_param. Thx wycats, koz and
josevalim for the suggestion.

AR's #to_key implementation now takes customized
primary keys into account and there's a testcase
for that too.

The #to_param AMo lint makes no assumptions on how
the method behaves in the presence of composite
primary keys. It leaves the decision wether to
provide a default, or to raise and thus signal to
the user that implementing this method will need
his special attention, up to the implementers. All
AMo cares about is that #to_param is implemented
and returns nil in case of a new_record?.

The default CompliantObject used in lint_test
provides a naive default implementation that just
joins all key attributes with '-'.

The #to_key default implementation in lint_test's
CompliantObject now returns [id] instead of [1].
This was previously causing the (wrong) tests I
added for AR's #to_key implementation to pass. The
#to_key tests added with this patch should be
better.

The CI failure was caused by my lack of knowledge
about the test:isolated task. The tests for the
record_identifier code in action_controller are
using fake non AR models and I forgot to stub the
#to_key method over there. This issue didn't come
up when running the test task, only test:isolated
revealed it. This patch fixes that.

All tests pass isolated or not, well, apart from
one previously unpended test in action_controller
that is unrelated to my patch.

8 files changed, 45 insertions, 29 deletions

diff --git a/actionpack/lib/action_controller/record_identifier.rb b/actionpack/lib/action_controller/record_identifier.rb
index 9c35c5b0c3..3f966b1b64 100644
--- a/actionpack/lib/action_controller/record_identifier.rb
+++ b/actionpack/lib/action_controller/record_identifier.rb
@@ -77,8 +77,8 @@ module ActionController
     # make sure yourself that your dom ids are valid, in case you overwrite this method.
     def record_key_for_dom_id(record)
       return record.id unless record.respond_to?(:to_model)
-      key = record.to_model.key
-      key ? sanitize_dom_id(key.join('-')) : key
+      key = record.to_model.to_key
+      key ? sanitize_dom_id(key.join('_')) : key
     end
 
     # Replaces characters that are invalid in HTML DOM ids with valid ones.
diff --git a/actionpack/test/controller/record_identifier_test.rb b/actionpack/test/controller/record_identifier_test.rb
index 6b6d154faa..813dedc80d 100644
--- a/actionpack/test/controller/record_identifier_test.rb
+++ b/actionpack/test/controller/record_identifier_test.rb
@@ -5,6 +5,7 @@ class Comment
   include ActiveModel::Conversion
 
   attr_reader :id
+  def to_key; id ? [id] : nil end
   def save; @id = 1 end
   def new_record?; @id.nil? end
   def name
diff --git a/actionpack/test/lib/controller/fake_models.rb b/actionpack/test/lib/controller/fake_models.rb
index e4aed14dc0..4475d40f63 100644
--- a/actionpack/test/lib/controller/fake_models.rb
+++ b/actionpack/test/lib/controller/fake_models.rb
@@ -6,7 +6,7 @@ class Customer < Struct.new(:name, :id)
 
   undef_method :to_json
 
-  def key
+  def to_key
     id ? [id] : nil
   end
 
@@ -47,7 +47,7 @@ module Quiz
     extend ActiveModel::Naming
     include ActiveModel::Conversion
 
-    def key
+    def to_key
       id ? [id] : nil
     end
 
@@ -67,7 +67,7 @@ class Post < Struct.new(:title, :author_name, :body, :secret, :written_on, :cost
 
   alias_method :secret?, :secret
 
-  def key
+  def to_key
     id ? [id] : nil
   end
 
@@ -96,7 +96,7 @@ class Comment
   attr_reader :id
   attr_reader :post_id
   def initialize(id = nil, post_id = nil); @id, @post_id = id, post_id end
-  def key; id ? [id] : nil end
+  def to_key; id ? [id] : nil end
   def save; @id = 1; @post_id = 1 end
   def new_record?; @id.nil? end
   def to_param; @id; end
@@ -116,7 +116,7 @@ class Tag
   attr_reader :id
   attr_reader :post_id
   def initialize(id = nil, post_id = nil); @id, @post_id = id, post_id end
-  def key; id ? [id] : nil end
+  def to_key; id ? [id] : nil end
   def save; @id = 1; @post_id = 1 end
   def new_record?; @id.nil? end
   def to_param; @id; end
@@ -136,7 +136,7 @@ class CommentRelevance
   attr_reader :id
   attr_reader :comment_id
   def initialize(id = nil, comment_id = nil); @id, @comment_id = id, comment_id end
-  def key; id ? [id] : nil end
+  def to_key; id ? [id] : nil end
   def save; @id = 1; @comment_id = 1 end
   def new_record?; @id.nil? end
   def to_param; @id; end
@@ -152,7 +152,7 @@ class TagRelevance
   attr_reader :id
   attr_reader :tag_id
   def initialize(id = nil, tag_id = nil); @id, @tag_id = id, tag_id end
-  def key; id ? [id] : nil end
+  def to_key; id ? [id] : nil end
   def save; @id = 1; @tag_id = 1 end
   def new_record?; @id.nil? end
   def to_param; @id; end
diff --git a/actionpack/test/template/prototype_helper_test.rb b/actionpack/test/template/prototype_helper_test.rb
index dab34f1201..45f9d85e32 100644
--- a/actionpack/test/template/prototype_helper_test.rb
+++ b/actionpack/test/template/prototype_helper_test.rb
@@ -4,7 +4,7 @@ require 'active_model'
 class Bunny < Struct.new(:Bunny, :id)
   extend ActiveModel::Naming
   include ActiveModel::Conversion
-  def key() id ? [id] : nil end
+  def to_key() id ? [id] : nil end
 end
 
 class Author
@@ -12,7 +12,7 @@ class Author
   include ActiveModel::Conversion
 
   attr_reader :id
-  def key() id ? [id] : nil end
+  def to_key() id ? [id] : nil end
   def save; @id = 1 end
   def new_record?; @id.nil? end
   def name
@@ -25,7 +25,7 @@ class Article
   include ActiveModel::Conversion
   attr_reader :id
   attr_reader :author_id
-  def key() id ? [id] : nil end
+  def to_key() id ? [id] : nil end
   def save; @id = 1; @author_id = 1 end
   def new_record?; @id.nil? end
   def name
diff --git a/activemodel/lib/active_model/lint.rb b/activemodel/lib/active_model/lint.rb
index c97286e61c..98413ac9fb 100644
--- a/activemodel/lib/active_model/lint.rb
+++ b/activemodel/lib/active_model/lint.rb
@@ -14,22 +14,28 @@ module ActiveModel
   module Lint
     module Tests
 
-      # == Responds to <tt>key</tt>
+      # == Responds to <tt>to_key</tt>
       #
       # Returns an Enumerable of all (primary) key attributes
       # or nil if model.new_record? is true
-      def test_key
-        assert model.respond_to?(:key), "The model should respond to key"
+      def test_to_key
+        assert model.respond_to?(:to_key), "The model should respond to to_key"
         def model.new_record?() true end
-        assert model.key.nil?
+        assert model.to_key.nil?
         def model.new_record?() false end
-        assert model.key.respond_to?(:each)
+        assert model.to_key.respond_to?(:each)
       end
 
       # == Responds to <tt>to_param</tt>
       #
       # Returns a string representing the object's key suitable for use in URLs
-      # or nil if model.new_record? is true
+      # or nil if model.new_record? is true.
+      #
+      # Implementers can decide to either raise an exception or provide a default
+      # in case the record uses a composite primary key. There are no tests for this
+      # behavior in lint because it doesn't make sense to force any of the possible
+      # implementation strategies on the implementer. However, if the resource is
+      # a new_record?, then to_param should always return nil.
       def test_to_param
         assert model.respond_to?(:to_param), "The model should respond to to_param"
         def model.new_record?() true end
diff --git a/activemodel/test/cases/lint_test.rb b/activemodel/test/cases/lint_test.rb
index 58716cbf85..99f8eff5d8 100644
--- a/activemodel/test/cases/lint_test.rb
+++ b/activemodel/test/cases/lint_test.rb
@@ -10,12 +10,14 @@ class LintTest < ActiveModel::TestCase
       self
     end
 
-    def key
-      new_record? ? nil : [1]
+    def to_key
+      new_record? ? nil : [id]
     end
 
     def to_param
-      key ? key.first.to_s : nil
+      return nil if to_key.nil?
+      # some default for CPKs, real implementations will differ
+      to_key.length > 1 ? to_key.join('-') : to_key.first.to_s
     end
 
     def valid?()      true end
diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index ba64b8ee2f..8549414a12 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -45,10 +45,12 @@ module ActiveRecord
         # Returns this record's primary key value wrapped in an Array
         # or nil if the record is a new_record?
         # This is done to comply with the AMo interface that expects
-        # every AMo compliant object to respond_to?(:key) and return
+        # every AMo compliant object to respond_to?(:to_key) and return
         # an Enumerable object from that call, or nil if new_record?
-        def key
-          new_record? ? nil : [ self.id ]
+        # This method also takes custom primary keys specified via
+        # the +set_primary_key+ into account.
+        def to_key
+          new_record? ? nil : [ self.send(self.class.primary_key) ]
         end
 
       end
diff --git a/activerecord/test/cases/pk_test.rb b/activerecord/test/cases/pk_test.rb
index 2502c136cc..5bba1d5625 100644
--- a/activerecord/test/cases/pk_test.rb
+++ b/activerecord/test/cases/pk_test.rb
@@ -9,13 +9,18 @@ require 'models/mixed_case_monkey'
 class PrimaryKeysTest < ActiveRecord::TestCase
   fixtures :topics, :subscribers, :movies, :mixed_case_monkeys
 
-  def test_key
-    # test new record
+  def test_to_key_with_default_primary_key
     topic = Topic.new
-    assert topic.key.nil?
-    # test existing record
+    assert topic.to_key.nil?
     topic = Topic.find(1)
-    assert_equal topic.key, [1]
+    assert_equal topic.to_key, [1]
+  end
+
+  def test_to_key_with_customized_primary_key
+    keyboard = Keyboard.new
+    assert keyboard.to_key.nil?
+    keyboard.save
+    assert_equal keyboard.to_key, [keyboard.id]
   end
 
   def test_integer_key