Merge branch 'master' into adequaterecord

* master: (108 commits)
  make tests pass on Ruby 2.2
  Use Sqlite3 adapter in examples
  use the body proxy to freeze headers
  just ask the response for the commit status, we do not need to ask the jar
  only write the jar if the response isn't committed
  Fix a grammatical error in the i18n guide [ci skip]
  use method_defined? to check whether or not a method is defined
  Enhance docs for update_attribute [ci-skip]
  Change usec to 0 on tests that compare seconds
  Unit test for mysql quote time usec
  Changelog entry for mysql56 microseconds
  Test microsecond on mysql 5.6
  MySQL 5.6 and later supports microsecond precision in datetime.
  [ci skip] Add documentation for original_fullpath.
  Remove mocking on save, when not necessary
  comment why we are modifying global state. [ci skip]
  `change_table` supports `citext`. Follow up to #12523.
  Removed unnecessary command "application"
  register OID for PostgreSQL citex datatype [Troy Kruthoff & Lachlan Sylvester]
  Fixes STI when 2+ levels deep.
  ...

20 files changed, 226 insertions, 106 deletions

diff --git a/actionpack/lib/action_controller/log_subscriber.rb b/actionpack/lib/action_controller/log_subscriber.rb
index e920a33765..b1acca2435 100644
--- a/actionpack/lib/action_controller/log_subscriber.rb
+++ b/actionpack/lib/action_controller/log_subscriber.rb
@@ -54,9 +54,9 @@ module ActionController
     end
 
     def deep_munge(event)
-      message = "Value for params[:#{event.payload[:keys].join('][:')}] was set"\
-                "to nil, because it was one of [], [null] or [null, null, ...]."\
-                "Go to http://guides.rubyonrails.org/security.html#unsafe-query-generation"\
+      message = "Value for params[:#{event.payload[:keys].join('][:')}] was set "\
+                "to nil, because it was one of [], [null] or [null, null, ...]. "\
+                "Go to http://guides.rubyonrails.org/security.html#unsafe-query-generation "\
                 "for more information."\
 
       debug(message)
diff --git a/actionpack/lib/action_controller/metal/live.rb b/actionpack/lib/action_controller/metal/live.rb
index fdf4ef293d..41b997a755 100644
--- a/actionpack/lib/action_controller/metal/live.rb
+++ b/actionpack/lib/action_controller/metal/live.rb
@@ -107,8 +107,11 @@ module ActionController
     end
 
     class Buffer < ActionDispatch::Response::Buffer #:nodoc:
+      include MonitorMixin
+
       def initialize(response)
-        @error_callback = nil
+        @error_callback = lambda { true }
+        @cv = new_cond
         super(response, SizedQueue.new(10))
       end
 
@@ -122,14 +125,25 @@ module ActionController
       end
 
       def each
+        @response.sending!
         while str = @buf.pop
           yield str
         end
+        @response.sent!
       end
 
       def close
-        super
-        @buf.push nil
+        synchronize do
+          super
+          @buf.push nil
+          @cv.broadcast
+        end
+      end
+
+      def await_close
+        synchronize do
+          @cv.wait_until { @closed }
+        end
       end
 
       def on_error(&block)
@@ -165,12 +179,20 @@ module ActionController
         end
       end
 
-      def commit!
-        headers.freeze
+      private
+
+      def before_committed
         super
+        jar = request.cookie_jar
+        # The response can be committed multiple times
+        jar.write self unless committed?
       end
 
-      private
+      def before_sending
+        super
+        request.cookie_jar.commit!
+        headers.freeze
+      end
 
       def build_buffer(response, body)
         buf = Live::Buffer.new response
@@ -191,6 +213,7 @@ module ActionController
       t1 = Thread.current
       locals = t1.keys.map { |key| [key, t1[key]] }
 
+      error = nil
       # This processes the action in a child thread. It lets us return the
       # response code and headers back up the rack stack, and still process
       # the body in parallel with sending data to the client
@@ -205,8 +228,9 @@ module ActionController
         begin
           super(name)
         rescue => e
-          @_response.status = 500 unless @_response.committed?
-          @_response.status = 400 if e.class == ActionController::BadRequest
+          unless @_response.committed?
+            error = e
+          end
           begin
             @_response.stream.write(ActionView::Base.streaming_completion_on_exception) if request.format == :html
             @_response.stream.call_on_error
@@ -222,6 +246,7 @@ module ActionController
       }
 
       @_response.await_commit
+      raise error if error
     end
 
     def log_error(exception)
diff --git a/actionpack/lib/action_controller/metal/rack_delegation.rb b/actionpack/lib/action_controller/metal/rack_delegation.rb
index e1bee9e60c..bdf6e88699 100644
--- a/actionpack/lib/action_controller/metal/rack_delegation.rb
+++ b/actionpack/lib/action_controller/metal/rack_delegation.rb
@@ -5,8 +5,8 @@ module ActionController
   module RackDelegation
     extend ActiveSupport::Concern
 
-    delegate :headers, :status=, :location=, :content_type=, :no_content_type=,
-             :status, :location, :content_type, :no_content_type, :to => "@_response"
+    delegate :headers, :status=, :location=, :content_type=,
+             :status, :location, :content_type, :to => "@_response"
 
     def dispatch(action, request)
       set_response!(request)
diff --git a/actionpack/lib/action_controller/metal/rendering.rb b/actionpack/lib/action_controller/metal/rendering.rb
index 3c4ef596c7..93e7d6954c 100644
--- a/actionpack/lib/action_controller/metal/rendering.rb
+++ b/actionpack/lib/action_controller/metal/rendering.rb
@@ -45,9 +45,7 @@ module ActionController
     def _process_format(format, options = {})
       super
 
-      if options[:body]
-        self.headers.delete "Content-Type"
-      elsif options[:plain]
+      if options[:plain]
         self.content_type = Mime::TEXT
       else
         self.content_type ||= format.to_s
diff --git a/actionpack/lib/action_controller/metal/request_forgery_protection.rb b/actionpack/lib/action_controller/metal/request_forgery_protection.rb
index c88074d4c6..e3b1f5ae7c 100644
--- a/actionpack/lib/action_controller/metal/request_forgery_protection.rb
+++ b/actionpack/lib/action_controller/metal/request_forgery_protection.rb
@@ -68,6 +68,10 @@ module ActionController #:nodoc:
       config_accessor :allow_forgery_protection
       self.allow_forgery_protection = true if allow_forgery_protection.nil?
 
+      # Controls whether a CSRF failure logs a warning. On by default.
+      config_accessor :log_warning_on_csrf_failure
+      self.log_warning_on_csrf_failure = true
+
       helper_method :form_authenticity_token
       helper_method :protect_against_forgery?
     end
@@ -193,7 +197,9 @@ module ActionController #:nodoc:
         mark_for_same_origin_verification!
 
         if !verified_request?
-          logger.warn "Can't verify CSRF token authenticity" if logger
+          if logger && log_warning_on_csrf_failure
+            logger.warn "Can't verify CSRF token authenticity"
+          end
           handle_unverified_request
         end
       end
diff --git a/actionpack/lib/action_controller/test_case.rb b/actionpack/lib/action_controller/test_case.rb
index 8650b75400..e9166d8747 100644
--- a/actionpack/lib/action_controller/test_case.rb
+++ b/actionpack/lib/action_controller/test_case.rb
@@ -258,6 +258,29 @@ module ActionController
     end
   end
 
+  class LiveTestResponse < Live::Response
+    def recycle!
+      @body = nil
+      initialize
+    end
+
+    def body
+      @body ||= super
+    end
+
+    # Was the response successful?
+    alias_method :success?, :successful?
+
+    # Was the URL not found?
+    alias_method :missing?, :not_found?
+
+    # Were we redirected?
+    alias_method :redirect?, :redirection?
+
+    # Was there a server-side error?
+    alias_method :error?, :server_error?
+  end
+
   # Methods #destroy and #load! are overridden to avoid calling methods on the
   # @store object, which does not exist for the TestSession class.
   class TestSession < Rack::Session::Abstract::SessionHash #:nodoc:
@@ -572,7 +595,9 @@ module ActionController
         @controller.process(name)
 
         if cookies = @request.env['action_dispatch.cookies']
-          cookies.write(@response)
+          unless @response.committed?
+            cookies.write(@response)
+          end
         end
         @response.prepare!
 
@@ -583,13 +608,14 @@ module ActionController
       end
 
       def setup_controller_request_and_response
-        @request          = build_request
-        @response         = build_response
-        @response.request = @request
-
         @controller = nil unless defined? @controller
 
+        response_klass = TestResponse
+
         if klass = self.class.controller_class
+          if klass < ActionController::Live
+            response_klass = LiveTestResponse
+          end
           unless @controller
             begin
               @controller = klass.new
@@ -599,6 +625,10 @@ module ActionController
           end
         end
 
+        @request          = build_request
+        @response         = build_response response_klass
+        @response.request = @request
+
         if @controller
           @controller.request = @request
           @controller.params = {}
@@ -609,8 +639,8 @@ module ActionController
         TestRequest.new
       end
 
-      def build_response
-        TestResponse.new
+      def build_response(klass)
+        klass.new
       end
 
       included do
diff --git a/actionpack/lib/action_dispatch/http/request.rb b/actionpack/lib/action_dispatch/http/request.rb
index 1318c62fbe..daa06e96e6 100644
--- a/actionpack/lib/action_dispatch/http/request.rb
+++ b/actionpack/lib/action_dispatch/http/request.rb
@@ -152,6 +152,13 @@ module ActionDispatch
       Http::Headers.new(@env)
     end
 
+    # Returns a +String+ with the last requested path including their params.
+    #
+    #    # get '/foo'
+    #    request.original_fullpath # => '/foo'
+    #
+    #    # get '/foo?bar'
+    #    request.original_fullpath # => '/foo?bar'
     def original_fullpath
       @original_fullpath ||= (env["ORIGINAL_FULLPATH"] || fullpath)
     end
diff --git a/actionpack/lib/action_dispatch/http/response.rb b/actionpack/lib/action_dispatch/http/response.rb
index f14ca1ea44..3d27ff2b24 100644
--- a/actionpack/lib/action_dispatch/http/response.rb
+++ b/actionpack/lib/action_dispatch/http/response.rb
@@ -63,8 +63,6 @@ module ActionDispatch # :nodoc:
     # content you're giving them, so we need to send that along.
     attr_accessor :charset
 
-    attr_accessor :no_content_type # :nodoc:
-
     CONTENT_TYPE = "Content-Type".freeze
     SET_COOKIE   = "Set-Cookie".freeze
     LOCATION     = "Location".freeze
@@ -93,7 +91,10 @@ module ActionDispatch # :nodoc:
       end
 
       def each(&block)
-        @buf.each(&block)
+        @response.sending!
+        x = @buf.each(&block)
+        @response.sent!
+        x
       end
 
       def close
@@ -120,6 +121,8 @@ module ActionDispatch # :nodoc:
       @blank        = false
       @cv           = new_cond
       @committed    = false
+      @sending      = false
+      @sent         = false
       @content_type = nil
       @charset      = nil
 
@@ -140,17 +143,37 @@ module ActionDispatch # :nodoc:
       end
     end
 
+    def await_sent
+      synchronize { @cv.wait_until { @sent } }
+    end
+
     def commit!
       synchronize do
+        before_committed
         @committed = true
         @cv.broadcast
       end
     end
 
-    def committed?
-      @committed
+    def sending!
+      synchronize do
+        before_sending
+        @sending = true
+        @cv.broadcast
+      end
+    end
+
+    def sent!
+      synchronize do
+        @sent = true
+        @cv.broadcast
+      end
     end
 
+    def sending?;   synchronize { @sending };   end
+    def committed?; synchronize { @committed }; end
+    def sent?;      synchronize { @sent };      end
+
     # Sets the HTTP status code.
     def status=(status)
       @status = Rack::Utils.status_code(status)
@@ -275,6 +298,12 @@ module ActionDispatch # :nodoc:
 
   private
 
+    def before_committed
+    end
+
+    def before_sending
+    end
+
     def merge_default_headers(original, default)
       return original unless default.respond_to?(:merge)
 
@@ -305,17 +334,8 @@ module ActionDispatch # :nodoc:
       !@sending_file && @charset != false
     end
 
-    def remove_content_type!
-      headers.delete CONTENT_TYPE
-    end
-
     def rack_response(status, header)
-      if no_content_type
-        remove_content_type!
-      else
-        assign_default_content_type_and_charset!(header)
-      end
-
+      assign_default_content_type_and_charset!(header)
       handle_conditional_get!
 
       header[SET_COOKIE] = header[SET_COOKIE].join("\n") if header[SET_COOKIE].respond_to?(:join)
diff --git a/actionpack/lib/action_dispatch/journey/formatter.rb b/actionpack/lib/action_dispatch/journey/formatter.rb
index 4410c1b5d5..57f0963731 100644
--- a/actionpack/lib/action_dispatch/journey/formatter.rb
+++ b/actionpack/lib/action_dispatch/journey/formatter.rb
@@ -121,9 +121,9 @@ module ActionDispatch
         def possibles(cache, options, depth = 0)
           cache.fetch(:___routes) { [] } + options.find_all { |pair|
             cache.key?(pair)
-          }.map { |pair|
+          }.flat_map { |pair|
             possibles(cache[pair], options, depth + 1)
-          }.flatten(1)
+          }
         end
 
         # Returns +true+ if no missing keys are present, otherwise +false+.
diff --git a/actionpack/lib/action_dispatch/journey/gtg/builder.rb b/actionpack/lib/action_dispatch/journey/gtg/builder.rb
index 7d2791714b..450588cda6 100644
--- a/actionpack/lib/action_dispatch/journey/gtg/builder.rb
+++ b/actionpack/lib/action_dispatch/journey/gtg/builder.rb
@@ -27,7 +27,7 @@ module ActionDispatch
             marked[s] = true # mark s
 
             s.group_by { |state| symbol(state) }.each do |sym, ps|
-              u = ps.map { |l| followpos(l) }.flatten
+              u = ps.flat_map { |l| followpos(l) }
               next if u.empty?
 
               if u.uniq == [DUMMY]
@@ -90,7 +90,7 @@ module ActionDispatch
               firstpos(node.left)
             end
           when Nodes::Or
-            node.children.map { |c| firstpos(c) }.flatten.uniq
+            node.children.flat_map { |c| firstpos(c) }.uniq
           when Nodes::Unary
             firstpos(node.left)
           when Nodes::Terminal
@@ -105,7 +105,7 @@ module ActionDispatch
           when Nodes::Star
             firstpos(node.left)
           when Nodes::Or
-            node.children.map { |c| lastpos(c) }.flatten.uniq
+            node.children.flat_map { |c| lastpos(c) }.uniq
           when Nodes::Cat
             if nullable?(node.right)
               lastpos(node.left) | lastpos(node.right)
diff --git a/actionpack/lib/action_dispatch/journey/gtg/simulator.rb b/actionpack/lib/action_dispatch/journey/gtg/simulator.rb
index 58ad803841..254c2befc4 100644
--- a/actionpack/lib/action_dispatch/journey/gtg/simulator.rb
+++ b/actionpack/lib/action_dispatch/journey/gtg/simulator.rb
@@ -31,7 +31,7 @@ module ActionDispatch
 
           return if acceptance_states.empty?
 
-          memos = acceptance_states.map { |x| tt.memo(x) }.flatten.compact
+          memos = acceptance_states.flat_map { |x| tt.memo(x) }.compact
 
           MatchData.new(memos)
         end
diff --git a/actionpack/lib/action_dispatch/journey/gtg/transition_table.rb b/actionpack/lib/action_dispatch/journey/gtg/transition_table.rb
index 5a79059ed6..e6212b1ee2 100644
--- a/actionpack/lib/action_dispatch/journey/gtg/transition_table.rb
+++ b/actionpack/lib/action_dispatch/journey/gtg/transition_table.rb
@@ -114,17 +114,17 @@ module ActionDispatch
         end
 
         def states
-          ss = @string_states.keys + @string_states.values.map(&:values).flatten
-          rs = @regexp_states.keys + @regexp_states.values.map(&:values).flatten
+          ss = @string_states.keys + @string_states.values.flat_map(&:values)
+          rs = @regexp_states.keys + @regexp_states.values.flat_map(&:values)
           (ss + rs).uniq
         end
 
         def transitions
-          @string_states.map { |from, hash|
+          @string_states.flat_map { |from, hash|
             hash.map { |s, to| [from, s, to] }
-          }.flatten(1) + @regexp_states.map { |from, hash|
+          } + @regexp_states.flat_map { |from, hash|
             hash.map { |s, to| [from, s, to] }
-          }.flatten(1)
+          }
         end
 
         private
@@ -143,11 +143,11 @@ module ActionDispatch
           def move_regexp(t, a)
             return [] if t.empty?
 
-            t.map { |s|
+            t.flat_map { |s|
               if states = @regexp_states[s]
                 states.map { |re, v| re === a ? v : nil }
               end
-            }.flatten.compact.uniq
+            }.compact.uniq
           end
 
           def move_string(t, a)
diff --git a/actionpack/lib/action_dispatch/journey/nfa/dot.rb b/actionpack/lib/action_dispatch/journey/nfa/dot.rb
index 5c33a872e5..47bf76bdbf 100644
--- a/actionpack/lib/action_dispatch/journey/nfa/dot.rb
+++ b/actionpack/lib/action_dispatch/journey/nfa/dot.rb
@@ -16,9 +16,9 @@ module ActionDispatch
           #  end
           #  "  #{n.object_id} [label=\"#{label}\", shape=box];"
           #}
-          #memo_edges = memos.map { |k, memos|
+          #memo_edges = memos.flat_map { |k, memos|
           #  (memos || []).map { |v| "  #{k} -> #{v.object_id};" }
-          #}.flatten.uniq
+          #}.uniq
 
         <<-eodot
 digraph nfa {
diff --git a/actionpack/lib/action_dispatch/journey/nfa/simulator.rb b/actionpack/lib/action_dispatch/journey/nfa/simulator.rb
index 5b40da6569..b23270db3c 100644
--- a/actionpack/lib/action_dispatch/journey/nfa/simulator.rb
+++ b/actionpack/lib/action_dispatch/journey/nfa/simulator.rb
@@ -34,7 +34,7 @@ module ActionDispatch
 
           return if acceptance_states.empty?
 
-          memos = acceptance_states.map { |x| tt.memo(x) }.flatten.compact
+          memos = acceptance_states.flat_map { |x| tt.memo(x) }.compact
 
           MatchData.new(memos)
         end
diff --git a/actionpack/lib/action_dispatch/journey/nfa/transition_table.rb b/actionpack/lib/action_dispatch/journey/nfa/transition_table.rb
index a3017aeea1..66e414213a 100644
--- a/actionpack/lib/action_dispatch/journey/nfa/transition_table.rb
+++ b/actionpack/lib/action_dispatch/journey/nfa/transition_table.rb
@@ -42,7 +42,7 @@ module ActionDispatch
         end
 
         def states
-          (@table.keys + @table.values.map(&:keys).flatten).uniq
+          (@table.keys + @table.values.flat_map(&:keys)).uniq
         end
 
         # Returns a generalized transition graph with reduced states. The states
@@ -93,7 +93,7 @@ module ActionDispatch
         # Returns set of NFA states to which there is a transition on ast symbol
         # +a+ from some state +s+ in +t+.
         def following_states(t, a)
-          Array(t).map { |s| inverted[s][a] }.flatten.uniq
+          Array(t).flat_map { |s| inverted[s][a] }.uniq
         end
 
         # Returns set of NFA states to which there is a transition on ast symbol
@@ -107,7 +107,7 @@ module ActionDispatch
         end
 
         def alphabet
-          inverted.values.map(&:keys).flatten.compact.uniq.sort_by { |x| x.to_s }
+          inverted.values.flat_map(&:keys).compact.uniq.sort_by { |x| x.to_s }
         end
 
         # Returns a set of NFA states reachable from some NFA state +s+ in set
@@ -131,9 +131,9 @@ module ActionDispatch
         end
 
         def transitions
-          @table.map { |to, hash|
+          @table.flat_map { |to, hash|
             hash.map { |from, sym| [from, sym, to] }
-          }.flatten(1)
+          }
         end
 
         private
diff --git a/actionpack/lib/action_dispatch/journey/path/pattern.rb b/actionpack/lib/action_dispatch/journey/path/pattern.rb
index d37aa1fbe5..fb155e516f 100644
--- a/actionpack/lib/action_dispatch/journey/path/pattern.rb
+++ b/actionpack/lib/action_dispatch/journey/path/pattern.rb
@@ -53,9 +53,9 @@ module ActionDispatch
         end
 
         def optional_names
-          @optional_names ||= spec.grep(Nodes::Group).map { |group|
+          @optional_names ||= spec.grep(Nodes::Group).flat_map { |group|
             group.grep(Nodes::Symbol)
-          }.flatten.map { |n| n.name }.uniq
+          }.map { |n| n.name }.uniq
         end
 
         class RegexpOffsets < Journey::Visitors::Visitor # :nodoc:
diff --git a/actionpack/lib/action_dispatch/middleware/cookies.rb b/actionpack/lib/action_dispatch/middleware/cookies.rb
index 18e64704f6..c0039fa3f5 100644
--- a/actionpack/lib/action_dispatch/middleware/cookies.rb
+++ b/actionpack/lib/action_dispatch/middleware/cookies.rb
@@ -74,7 +74,7 @@ module ActionDispatch
   #
   #     domain: nil  # Does not sets cookie domain. (default)
   #     domain: :all # Allow the cookie for the top most level
-  #                       domain and subdomains.
+  #                  # domain and subdomains.
   #
   # * <tt>:expires</tt> - The time at which this cookie expires, as a \Time object.
   # * <tt>:secure</tt> - Whether this cookie is only transmitted to HTTPS servers.
@@ -237,6 +237,15 @@ module ActionDispatch
         @secure = secure
         @options = options
         @cookies = {}
+        @committed = false
+      end
+
+      def committed?; @committed; end
+
+      def commit!
+        @committed = true
+        @set_cookies.freeze
+        @delete_cookies.freeze
       end
 
       def each(&block)
@@ -336,8 +345,8 @@ module ActionDispatch
       end
 
       def recycle! #:nodoc:
-        @set_cookies.clear
-        @delete_cookies.clear
+        @set_cookies = {}
+        @delete_cookies = {}
       end
 
       mattr_accessor :always_write_cookie
@@ -551,9 +560,11 @@ module ActionDispatch
       status, headers, body = @app.call(env)
 
       if cookie_jar = env['action_dispatch.cookies']
-        cookie_jar.write(headers)
-        if headers[HTTP_HEADER].respond_to?(:join)
-          headers[HTTP_HEADER] = headers[HTTP_HEADER].join("\n")
+        unless cookie_jar.committed?
+          cookie_jar.write(headers)
+          if headers[HTTP_HEADER].respond_to?(:join)
+            headers[HTTP_HEADER] = headers[HTTP_HEADER].join("\n")
+          end
         end
       end
 
diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 0b762aa9a4..357829e59f 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -708,7 +708,8 @@ module ActionDispatch
           options[:constraints] ||= {}
 
           unless shallow?
-            options[:shallow_path] = options[:path] if args.any?
+            options[:shallow_path] ||= options[:path] if options.key?(:path)
+            options[:shallow_prefix] ||= options[:as] if options.key?(:as)
           end
 
           if options[:constraints].is_a?(Hash)
@@ -792,9 +793,16 @@ module ActionDispatch
         #   end
         def namespace(path, options = {})
           path = path.to_s
-          options = { :path => path, :as => path, :module => path,
-                      :shallow_path => path, :shallow_prefix => path }.merge!(options)
-          scope(options) { yield }
+
+          defaults = {
+            module:         path,
+            path:           options.fetch(:path, path),
+            as:             options.fetch(:as, path),
+            shallow_path:   options.fetch(:path, path),
+            shallow_prefix: options.fetch(:as, path)
+          }
+
+          scope(defaults.merge!(options)) { yield }
         end
 
         # === Parameter Restriction
@@ -1323,8 +1331,10 @@ module ActionDispatch
           end
 
           with_scope_level(:member) do
-            scope(parent_resource.member_scope) do
-              yield
+            if shallow?
+              shallow_scope(parent_resource.member_scope) { yield }
+            else
+              scope(parent_resource.member_scope) { yield }
             end
           end
         end
@@ -1347,16 +1357,8 @@ module ActionDispatch
           end
 
           with_scope_level(:nested) do
-            if shallow?
-              with_exclusive_scope do
-                if @scope[:shallow_path].blank?
-                  scope(parent_resource.nested_scope, nested_options) { yield }
-                else
-                  scope(@scope[:shallow_path], :as => @scope[:shallow_prefix]) do
-                    scope(parent_resource.nested_scope, nested_options) { yield }
-                  end
-                end
-              end
+            if shallow? && nesting_depth > 1
+              shallow_scope(parent_resource.nested_scope, nested_options) { yield }
             else
               scope(parent_resource.nested_scope, nested_options) { yield }
             end
@@ -1558,21 +1560,23 @@ module ActionDispatch
             end
           end
 
-          def with_scope_level(kind, resource = parent_resource)
+          def with_scope_level(kind)
             old, @scope[:scope_level] = @scope[:scope_level], kind
-            old_resource, @scope[:scope_level_resource] = @scope[:scope_level_resource], resource
             yield
           ensure
             @scope[:scope_level] = old
-            @scope[:scope_level_resource] = old_resource
           end
 
           def resource_scope(kind, resource) #:nodoc:
-            with_scope_level(kind, resource) do
-              scope(parent_resource.resource_scope) do
-                yield
-              end
+            old_resource, @scope[:scope_level_resource] = @scope[:scope_level_resource], resource
+            @nesting.push(resource)
+
+            with_scope_level(kind) do
+              scope(parent_resource.resource_scope) { yield }
             end
+          ensure
+            @nesting.pop
+            @scope[:scope_level_resource] = old_resource
           end
 
           def nested_options #:nodoc:
@@ -1584,6 +1588,10 @@ module ActionDispatch
             options
           end
 
+          def nesting_depth #:nodoc:
+            @nesting.size
+          end
+
           def param_constraint? #:nodoc:
             @scope[:constraints] && @scope[:constraints][parent_resource.param].is_a?(Regexp)
           end
@@ -1596,18 +1604,20 @@ module ActionDispatch
             flag && resource_method_scope? && CANONICAL_ACTIONS.include?(action.to_s)
           end
 
-          def shallow_scoping? #:nodoc:
-            shallow? && @scope[:scope_level] == :member
+          def shallow_scope(path, options = {}) #:nodoc:
+            old_name_prefix, old_path = @scope[:as], @scope[:path]
+            @scope[:as], @scope[:path] = @scope[:shallow_prefix], @scope[:shallow_path]
+
+            scope(path, options) { yield }
+          ensure
+            @scope[:as], @scope[:path] = old_name_prefix, old_path
           end
 
           def path_for_action(action, path) #:nodoc:
-            prefix = shallow_scoping? ?
-              "#{@scope[:shallow_path]}/#{parent_resource.shallow_scope}" : @scope[:path]
-
             if canonical_action?(action, path.blank?)
-              prefix.to_s
+              @scope[:path].to_s
             else
-              "#{prefix}/#{action_path(action, path)}"
+              "#{@scope[:path]}/#{action_path(action, path)}"
             end
           end
 
@@ -1645,7 +1655,7 @@ module ActionDispatch
             when :new
               [prefix, :new, name_prefix, member_name]
             when :member
-              [prefix, shallow_scoping? ? @scope[:shallow_prefix] : name_prefix, member_name]
+              [prefix, name_prefix, member_name]
             when :root
               [name_prefix, collection_name, prefix]
             else
@@ -1786,6 +1796,7 @@ module ActionDispatch
         @set = set
         @scope = { :path_names => @set.resources_path_names }
         @concerns = {}
+        @nesting = []
       end
 
       include Base
diff --git a/actionpack/lib/action_pack/gem_version.rb b/actionpack/lib/action_pack/gem_version.rb
new file mode 100644
index 0000000000..beaf35d3da
--- /dev/null
+++ b/actionpack/lib/action_pack/gem_version.rb
@@ -0,0 +1,15 @@
+module ActionPack
+  # Returns the version of the currently loaded ActionPack as a <tt>Gem::Version</tt>
+  def self.gem_version
+    Gem::Version.new VERSION::STRING
+  end
+
+  module VERSION
+    MAJOR = 4
+    MINOR = 2
+    TINY  = 0
+    PRE   = "alpha"
+
+    STRING = [MAJOR, MINOR, TINY, PRE].compact.join(".")
+  end
+end
diff --git a/actionpack/lib/action_pack/version.rb b/actionpack/lib/action_pack/version.rb
index 75fb0d9532..7088cd2760 100644
--- a/actionpack/lib/action_pack/version.rb
+++ b/actionpack/lib/action_pack/version.rb
@@ -1,11 +1,8 @@
+require_relative 'gem_version'
+
 module ActionPack
-  # Returns the version of the currently loaded ActionPack as a Gem::Version
+  # Returns the version of the currently loaded ActionPack as a <tt>Gem::Version</tt>
   def self.version
-    Gem::Version.new "4.2.0.alpha"
-  end
-
-  module VERSION #:nodoc:
-    MAJOR, MINOR, TINY, PRE = ActionPack.version.segments
-    STRING = ActionPack.version.to_s
+    gem_version
   end
 end