[core] Merge pull request rspec/rspec-core#1081 from rspec/deprecatio…

…n_warning_let_subject_before_all

Add a deprecation warning to 2.99 for accessing let/subject from `after(:all)`

---
This commit was imported from rspec/rspec-core@a807624.

rspec-core/Changelog.md

@@ -23,6 +23,8 @@ Deprecations
   debugger gem) instead (Myron Marston).
 * Deprecate `RSpec.configuration.treat_symbols_as_metadata_keys_with_true_values = false`.
   RSpec 3 will not support having this option set to `false` (Myron Marston).
+* Deprecate accessing a `let` or `subject` declaration in
+  a `after(:all)` hook. (Myron Marston, Jon Rowe)
 
 ### 2.14.5 / 2013-08-13
 [full changelog](http://github.com/rspec/rspec-core/compare/v2.14.4...v2.14.5)

rspec-core/lib/rspec/core/example_group.rb

@@ -380,7 +380,7 @@ def self.run_before_all_hooks(example_group_instance)
         begin
           assign_before_all_ivars(superclass.before_all_ivars, example_group_instance)
 
-          BeforeAllMemoizedHash.isolate_for_before_all(example_group_instance) do
+          AllHookMemoizedHash::Before.isolate_for_all_hook(example_group_instance) do
             run_hook(:before, :all, example_group_instance)
           end
         ensure
@@ -408,7 +408,9 @@ def self.run_after_all_hooks(example_group_instance)
         return if descendant_filtered_examples.empty?
         assign_before_all_ivars(before_all_ivars, example_group_instance)
 
-        run_hook(:after, :all, example_group_instance)
+        AllHookMemoizedHash::After.isolate_for_all_hook(example_group_instance) do
+          run_hook(:after, :all, example_group_instance)
+        end
       end
 
       # Runs all the examples in this group

rspec-core/lib/rspec/core/memoized_helpers.rb

@@ -93,15 +93,12 @@ def __memoized
       # memoized hash when used in a `before(:all)` hook.
       #
       # @private
-      class BeforeAllMemoizedHash
-        def initialize(example_group_instance)
-          @example_group_instance = example_group_instance
-          @hash = {}
-        end
+      class AllHookMemoizedHash
+        def self.isolate_for_all_hook(example_group_instance)
+          hash_type = self
 
-        def self.isolate_for_before_all(example_group_instance)
           example_group_instance.instance_eval do
-            @__memoized = BeforeAllMemoizedHash.new(self)
+            @__memoized = hash_type.new(example_group_instance)
 
             begin
               yield
@@ -112,6 +109,11 @@ def self.isolate_for_before_all(example_group_instance)
           end
         end
 
+        def initialize(example_group_instance)
+          @example_group_instance = example_group_instance
+          @hash = {}
+        end
+
         def fetch(key, &block)
           description = if key == :subject
             "subject"
@@ -120,17 +122,16 @@ def fetch(key, &block)
           end
 
           ::RSpec.warn_deprecation <<-EOS
-WARNING: #{description} accessed in a `before(:all)` hook at:
+DEPRECATION: #{description} accessed in #{article} #{hook_expression} hook at:
   #{CallerFilter.first_non_rspec_line}
 
-This is deprecated behavior that will not be supported in RSpec 3.
-
 `let` and `subject` declarations are not intended to be called
-in a `before(:all)` hook, as they exist to define state that
-is reset between each example, while `before(:all)` exists to
-define state that is shared across examples in an example group.
-EOS
+in #{article} #{hook_expression} hook, as they exist to define state that
+is reset between each example, while #{hook_expression} exists to
+#{hook_intention}.
 
+This is deprecated behavior that will not be supported in RSpec 3.
+EOS
           @hash.fetch(key, &block)
         end
 
@@ -148,6 +149,34 @@ def preserve_accessed_lets
             end
           end
         end
+
+        class Before < self
+          def hook_expression
+            "`before(:all)`"
+          end
+
+          def article
+            "a"
+          end
+
+          def hook_intention
+            "define state that is shared across examples in an example group"
+          end
+        end
+
+        class After < self
+          def hook_expression
+            "`after(:all)`"
+          end
+
+          def article
+            "an"
+          end
+
+          def hook_intention
+            "cleanup state that is shared across examples in an example group"
+          end
+        end
       end
 
       def self.included(mod)