Support proc options with zero args

Fixes #40.

Author: pixeltrix

CHANGELOG.md

@@ -1,3 +1,9 @@
+*   Support proc options with zero arguments
+
+    Fixes #40.
+
+    *Andrew White*
+
 *   The options `:layout` and `:cache_path` now behave the same when
     passed a `Symbol`, `Proc` or object that responds to call.
 

lib/action_controller/caching/actions.rb

@@ -183,8 +183,17 @@ def render_to_string(controller, body)
 
         private
           def expand_option(controller, option)
-            if option.is_a?(Proc) || option.respond_to?(:to_proc)
-              controller.instance_exec(controller, &option)
+            option = option.to_proc if option.respond_to?(:to_proc)
+
+            if option.is_a?(Proc)
+              case option.arity
+              when -2, -1, 1
+                controller.instance_exec(controller, &option)
+              when 0
+                controller.instance_exec(&option)
+              else
+                raise ArgumentError, "Invalid proc arity of #{option.arity} - proc options should have an arity of 0 or 1"
+              end
             elsif option.respond_to?(:call)
               option.call(controller)
             else

test/caching_test.rb

@@ -40,8 +40,10 @@ class ActionCachingTestController < CachingController
   caches_action :with_format_and_http_param, cache_path: ->(c) { { key: "value" } }
   caches_action :with_symbol_format, cache_path: "http://test.host/action_caching_test/with_symbol_format"
   caches_action :not_url_cache_path, cache_path: ->(c) { "#{c.params[:action]}_key" }
+  caches_action :not_url_cache_path_no_args, cache_path: -> { "#{params[:action]}_key" }
   caches_action :layout_false, layout: false
   caches_action :with_layout_proc_param, layout: ->(c) { c.params[:layout] != "false" }
+  caches_action :with_layout_proc_param_no_args, layout: -> { params[:layout] != "false" }
   caches_action :record_not_found, :four_oh_four, :simple_runtime_error
   caches_action :streaming
   caches_action :invalid
@@ -81,6 +83,7 @@ def with_symbol_format
   def not_url_cache_path
     render plain: "cache_this"
   end
+  alias_method :not_url_cache_path_no_args, :not_url_cache_path
 
   def record_not_found
     raise ActiveRecord::RecordNotFound, "oops!"
@@ -101,6 +104,7 @@ def simple_runtime_error
   alias_method :symbol_cache_path, :index
   alias_method :layout_false, :with_layout
   alias_method :with_layout_proc_param, :with_layout
+  alias_method :with_layout_proc_param_no_args, :with_layout
 
   def expire
     expire_action controller: "action_caching_test", action: "index"
@@ -807,6 +811,29 @@ def test_explicit_html_format_is_used_for_fragment_path
     assert_not_cached cached_time
   end
 
+  def test_lambda_arity
+    draw do
+      get "/action_caching_test/not_url_cache_path_no_args", to: "action_caching_test#not_url_cache_path_no_args"
+      get "/action_caching_test/with_layout_proc_param_no_args", to: "action_caching_test#with_layout_proc_param_no_args"
+    end
+
+    get :not_url_cache_path_no_args
+    assert_response :success
+    assert !fragment_exist?("test.host/action_caching_test/not_url_cache_path_no_args")
+    assert fragment_exist?("not_url_cache_path_no_args_key")
+
+    get :with_layout_proc_param_no_args, params: { title: "Request 1", layout: "false" }
+    assert_response :success
+    cached_time = content_to_cache
+    assert_equal "<title>Request 1</title>\n#{cached_time}", @response.body
+    assert_equal cached_time, read_fragment("hostname.com/action_caching_test/with_layout_proc_param_no_args")
+
+    get :with_layout_proc_param_no_args, params: { title: "Request 2", layout: "false" }
+    assert_response :success
+    assert_equal "<title>Request 2</title>\n#{cached_time}", @response.body
+    assert_equal cached_time, read_fragment("hostname.com/action_caching_test/with_layout_proc_param_no_args")
+  end
+
   private
     def get_html(*args)
       @request.accept = "text/html"