Deprecate custom patterns for PathResolver

Custom glob patterns tie the implementation (Using Dir.glob) to the API
we provide.

It also doesn't really work. extract_handler_and_format_and_variant
expects the handler, format, and variant to be at the end of the
template path, and in the same order as they are in the default pattern.

This deprecates specifying a custom path for FileSystemResolver and
removes the pattern argument of OptimizedFileSystemResolver#initialize,
which does not work with a custom pattern.

actionview/lib/action_view/template/resolver.rb

@@ -168,7 +168,12 @@ class PathResolver < Resolver #:nodoc:
     DEFAULT_PATTERN = ":prefix/:action{.:locale,}{.:formats,}{+:variants,}{.:handlers,}"
 
     def initialize(pattern = nil)
-      @pattern = pattern || DEFAULT_PATTERN
+      if pattern
+        ActiveSupport::Deprecation.warn "Specifying a custom path for #{self.class} is deprecated. Implement a custom Resolver subclass instead."
+        @pattern = pattern
+      else
+        @pattern = DEFAULT_PATTERN
+      end
       super()
     end
 
@@ -273,44 +278,7 @@ def extract_handler_and_format_and_variant(path)
       end
   end
 
-  # A resolver that loads files from the filesystem. It allows setting your own
-  # resolving pattern. Such pattern can be a glob string supported by some variables.
-  #
-  # ==== Examples
-  #
-  # Default pattern, loads views the same way as previous versions of rails, eg. when you're
-  # looking for <tt>users/new</tt> it will produce query glob: <tt>users/new{.{en},}{.{html,js},}{.{erb,haml},}</tt>
-  #
-  #   FileSystemResolver.new("/path/to/views", ":prefix/:action{.:locale,}{.:formats,}{+:variants,}{.:handlers,}")
-  #
-  # This one allows you to keep files with different formats in separate subdirectories,
-  # eg. <tt>users/new.html</tt> will be loaded from <tt>users/html/new.erb</tt> or <tt>users/new.html.erb</tt>,
-  # <tt>users/new.js</tt> from <tt>users/js/new.erb</tt> or <tt>users/new.js.erb</tt>, etc.
-  #
-  #   FileSystemResolver.new("/path/to/views", ":prefix/{:formats/,}:action{.:locale,}{.:formats,}{+:variants,}{.:handlers,}")
-  #
-  # If you don't specify a pattern then the default will be used.
-  #
-  # In order to use any of the customized resolvers above in a Rails application, you just need
-  # to configure ActionController::Base.view_paths in an initializer, for example:
-  #
-  #   ActionController::Base.view_paths = FileSystemResolver.new(
-  #     Rails.root.join("app/views"),
-  #     ":prefix/:action{.:locale,}{.:formats,}{+:variants,}{.:handlers,}",
-  #   )
-  #
-  # ==== Pattern format and variables
-  #
-  # Pattern has to be a valid glob string, and it allows you to use the
-  # following variables:
-  #
-  # * <tt>:prefix</tt> - usually the controller path
-  # * <tt>:action</tt> - name of the action
-  # * <tt>:locale</tt> - possible locale versions
-  # * <tt>:formats</tt> - possible request formats (for example html, json, xml...)
-  # * <tt>:variants</tt> - possible request variants (for example phone, tablet...)
-  # * <tt>:handlers</tt> - possible handlers (for example erb, haml, builder...)
-  #
+  # A resolver that loads files from the filesystem.
   class FileSystemResolver < PathResolver
     def initialize(path, pattern = nil)
       raise ArgumentError, "path already is a Resolver class" if path.is_a?(Resolver)
@@ -331,6 +299,10 @@ def eql?(resolver)
 
   # An Optimized resolver for Rails' most common case.
   class OptimizedFileSystemResolver < FileSystemResolver #:nodoc:
+    def initialize(path)
+      super(path)
+    end
+
     private
 
       def find_template_paths_from_details(path, details)

actionview/test/template/resolver_patterns_test.rb

@@ -6,7 +6,10 @@ class ResolverPatternsTest < ActiveSupport::TestCase
   def setup
     path = File.expand_path("../fixtures", __dir__)
     pattern = ":prefix/{:formats/,}:action{.:formats,}{+:variants,}{.:handlers,}"
-    @resolver = ActionView::FileSystemResolver.new(path, pattern)
+
+    assert_deprecated do
+      @resolver = ActionView::FileSystemResolver.new(path, pattern)
+    end
   end
 
   def test_should_return_empty_list_for_unknown_path