Bring abstract_controller up to date with rails/master

Resolved all the conflicts since 2.3.0 -> HEAD. Following is a list
of commits that could not be applied cleanly or are obviated with the
abstract_controller refactor. They all need to be revisited to ensure
that fixes made in 2.3 do not reappear in 3.0:

2259ecf368e6a6715966f69216e3ee86bf1a82a7
AR not available
  * This will be reimplemented with ActionORM or equivalent

06182ea02e92afad579998aa80144588e8865ac3
implicitly rendering a js response should not use the default layout
[#1844 state:resolved]
  * This will be handled generically

893e9eb99504705419ad6edac14d00e71cef5f12
Improve view rendering performance in development mode and reinstate
template recompiling in production [#1909 state:resolved]
  * We will need to reimplement rails-dev-boost on top of the refactor;
    the changes here are very implementation specific and cannot be
    cleanly applied. The following commits are implicated:

      199e750d46c04970b5e7684998d09405648ecbd4
      3942cb406e1d5db0ac00e03153809cc8dc4cc4db
      f8ea9f85d4f1e3e6f3b5d895bef6b013aa4b0690
      e3b166aab37ddc2fbab030b146eb61713b91bf55
      ae9f258e03c9fd5088da12c1c6cd216cc89a01f7
      44423126c6f6133a1d9cf1d0832b527e8711d40f

0cb020b4d6d838025859bd60fb8151c8e21b8e84
workaround for picking layouts based on wrong view_paths
[#1974 state:resolved]
  * The specifics of this commit no longer apply. Since it is a two-line
    commit, we will reimplement this change.

8c5cc66a831aadb159f3daaffa4208064c30af0e
make action_controller/layouts pick templates from the current instance's
view_paths instead of the class view_paths [#1974 state:resolved]
  * This does not apply at all. It should be trivial to apply the feature
    to the reimplemented ActionController::Base.

87e8b162463f13bd50d27398f020769460a770e3
fix HTML fallback for explicit templates [#2052 state:resolved]
  * There were a number of patches related to this that simply compounded
    each other. Basically none of them apply cleanly, and the underlying
    issue needs to be revisited. After discussing the underlying problem
    with Koz, we will defer these fixes for further discussion.

1 files changed, 46 insertions, 57 deletions

diff --git a/activerecord/lib/active_record/fixtures.rb b/activerecord/lib/active_record/fixtures.rb
index 0131d9fac5..c6501113bf 100644
--- a/activerecord/lib/active_record/fixtures.rb
+++ b/activerecord/lib/active_record/fixtures.rb
@@ -21,13 +21,17 @@ else
   end
 end
 
-# Fixtures are a way of organizing data that you want to test against; in short, sample data. They come in 3 flavors:
+# Fixtures are a way of organizing data that you want to test against; in short, sample data.
+#
+# = Fixture formats
+#
+# Fixtures come in 3 flavors:
 #
 #   1.  YAML fixtures
 #   2.  CSV fixtures
 #   3.  Single-file fixtures
 #
-# = YAML fixtures
+# == YAML fixtures
 #
 # This type of fixture is in YAML format and the preferred default. YAML is a file format which describes data structures
 # in a non-verbose, human-readable format. It ships with Ruby 1.8.1+.
@@ -65,9 +69,9 @@ end
 #        parent_id:  1
 #        title:      Child
 #
-# = CSV fixtures
+# == CSV fixtures
 #
-# Fixtures can also be kept in the Comma Separated Value format. Akin to YAML fixtures, CSV fixtures are stored
+# Fixtures can also be kept in the Comma Separated Value (CSV) format. Akin to YAML fixtures, CSV fixtures are stored
 # in a single file, but instead end with the <tt>.csv</tt> file extension
 # (Rails example: <tt><your-rails-app>/test/fixtures/web_sites.csv</tt>).
 #
@@ -90,7 +94,7 @@ end
 # Most databases and spreadsheets support exporting to CSV format, so this is a great format for you to choose if you
 # have existing data somewhere already.
 #
-# = Single-file fixtures
+# == Single-file fixtures
 #
 # This type of fixture was the original format for Active Record that has since been deprecated in favor of the YAML and CSV formats.
 # Fixtures for this format are created by placing text files in a sub-directory (with the name of the model) to the directory
@@ -113,65 +117,53 @@ end
 #   name => Ruby on Rails
 #   url => http://www.rubyonrails.org
 #
-# = Using Fixtures
+# = Using fixtures in testcases
 #
 # Since fixtures are a testing construct, we use them in our unit and functional tests.  There are two ways to use the
 # fixtures, but first let's take a look at a sample unit test:
 #
-#   require 'web_site'
+#   require 'test_helper'
 #
 #   class WebSiteTest < ActiveSupport::TestCase
-#     def test_web_site_count
+#     test "web_site_count" do
 #       assert_equal 2, WebSite.count
 #     end
 #   end
 #
-# As it stands, unless we pre-load the web_site table in our database with two records, this test will fail.  Here's the
-# easiest way to add fixtures to the database:
-#
-#   ...
-#   class WebSiteTest < ActiveSupport::TestCase
-#     fixtures :web_sites # add more by separating the symbols with commas
-#   ...
-#
-# By adding a "fixtures" method to the test case and passing it a list of symbols (only one is shown here though), we trigger
-# the testing environment to automatically load the appropriate fixtures into the database before each test.
+# By default, the <tt>test_helper module</tt> will load all of your fixtures into your test database, so this test will succeed.
+# The testing environment will automatically load the all fixtures into the database before each test.
 # To ensure consistent data, the environment deletes the fixtures before running the load.
 #
-# In addition to being available in the database, the fixtures are also loaded into a hash stored in an instance variable
-# of the test case.  It is named after the symbol... so, in our example, there would be a hash available called
-# <tt>@web_sites</tt>.  This is where the "fixture name" comes into play.
-#
-# On top of that, each record is automatically "found" (using <tt>Model.find(id)</tt>) and placed in the instance variable of its name.
-# So for the YAML fixtures, we'd get <tt>@rubyonrails</tt> and <tt>@google</tt>, which could be interrogated using regular Active Record semantics:
+# In addition to being available in the database, the fixture's data may also be accessed by
+# using a special dynamic method, which has the same name as the model, and accepts the
+# name of the fixture to instantiate:
 #
-#   # test if the object created from the fixture data has the same attributes as the data itself
-#   def test_find
-#     assert_equal @web_sites["rubyonrails"]["name"], @rubyonrails.name
+#   test "find" do
+#     assert_equal "Ruby on Rails", web_sites(:rubyonrails).name
 #   end
 #
-# As seen above, the data hash created from the YAML fixtures would have <tt>@web_sites["rubyonrails"]["url"]</tt> return
-# "http://www.rubyonrails.org" and <tt>@web_sites["google"]["name"]</tt> would return "Google". The same fixtures, but loaded
-# from a CSV fixture file, would be accessible via <tt>@web_sites["web_site_1"]["name"] == "Ruby on Rails"</tt> and have the individual
-# fixtures available as instance variables <tt>@web_site_1</tt> and <tt>@web_site_2</tt>.
+# Alternatively, you may enable auto-instantiation of the fixture data. For instance, take the following tests:
 #
-# If you do not wish to use instantiated fixtures (usually for performance reasons) there are two options.
+#   test "find_alt_method_1" do
+#     assert_equal "Ruby on Rails", @web_sites['rubyonrails']['name']
+#   end
 #
-#   - to completely disable instantiated fixtures:
-#       self.use_instantiated_fixtures = false
+#   test "find_alt_method_2" do
+#     assert_equal "Ruby on Rails", @rubyonrails.news
+#   end
 #
-#   - to keep the fixture instance (@web_sites) available, but do not automatically 'find' each instance:
-#       self.use_instantiated_fixtures = :no_instances
+# In order to use these methods to access fixtured data within your testcases, you must specify one of the
+# following in your <tt>ActiveSupport::TestCase</tt>-derived class:
 #
-# Even if auto-instantiated fixtures are disabled, you can still access them
-# by name via special dynamic methods. Each method has the same name as the
-# model, and accepts the name of the fixture to instantiate:
+# - to fully enable instantiated fixtures (enable alternate methods #1 and #2 above)
+#     self.use_instantiated_fixtures = true
 #
-#   fixtures :web_sites
+# - create only the hash for the fixtures, do not 'find' each instance (enable alternate method #1 only)
+#     self.use_instantiated_fixtures = :no_instances
 #
-#   def test_find
-#     assert_equal "Ruby on Rails", web_sites(:rubyonrails).name
-#   end
+# Using either of these alternate methods incurs a performance hit, as the fixtured data must be fully
+# traversed in the database to create the fixture hash and/or instance variables. This is expensive for
+# large sets of fixtured data.
 #
 # = Dynamic fixtures with ERb
 #
@@ -194,21 +186,17 @@ end
 # = Transactional fixtures
 #
 # TestCases can use begin+rollback to isolate their changes to the database instead of having to delete+insert for every test case.
-# They can also turn off auto-instantiation of fixture data since the feature is costly and often unused.
 #
 #   class FooTest < ActiveSupport::TestCase
 #     self.use_transactional_fixtures = true
-#     self.use_instantiated_fixtures = false
-#
-#     fixtures :foos
 #
-#     def test_godzilla
+#     test "godzilla" do
 #       assert !Foo.find(:all).empty?
 #       Foo.destroy_all
 #       assert Foo.find(:all).empty?
 #     end
 #
-#     def test_godzilla_aftermath
+#     test "godzilla aftermath" do
 #       assert !Foo.find(:all).empty?
 #     end
 #   end
@@ -220,24 +208,25 @@ end
 # access to fixture data for every table that has been loaded through fixtures (depending on the value of +use_instantiated_fixtures+)
 #
 # When *not* to use transactional fixtures:
-#   1. You're testing whether a transaction works correctly. Nested transactions don't commit until all parent transactions commit,
-#      particularly, the fixtures transaction which is begun in setup and rolled back in teardown. Thus, you won't be able to verify
-#      the results of your transaction until Active Record supports nested transactions or savepoints (in progress).
-#   2. Your database does not support transactions. Every Active Record database supports transactions except MySQL MyISAM.
-#      Use InnoDB, MaxDB, or NDB instead.
+#
+# 1. You're testing whether a transaction works correctly. Nested transactions don't commit until all parent transactions commit,
+#    particularly, the fixtures transaction which is begun in setup and rolled back in teardown. Thus, you won't be able to verify
+#    the results of your transaction until Active Record supports nested transactions or savepoints (in progress).
+# 2. Your database does not support transactions. Every Active Record database supports transactions except MySQL MyISAM.
+#    Use InnoDB, MaxDB, or NDB instead.
 #
 # = Advanced YAML Fixtures
 #
 # YAML fixtures that don't specify an ID get some extra features:
 #
-# * Stable, autogenerated ID's
+# * Stable, autogenerated IDs
 # * Label references for associations (belongs_to, has_one, has_many)
 # * HABTM associations as inline lists
 # * Autofilled timestamp columns
 # * Fixture label interpolation
 # * Support for YAML defaults
 #
-# == Stable, autogenerated ID's
+# == Stable, autogenerated IDs
 #
 # Here, have a monkey fixture:
 #
@@ -292,7 +281,7 @@ end
 #
 # Add a few more monkeys and pirates and break this into multiple files,
 # and it gets pretty hard to keep track of what's going on. Let's
-# use labels instead of ID's:
+# use labels instead of IDs:
 #
 #   ### in pirates.yml
 #