close #365; VersionConcern#version_at should return nil if timestamp argument received is after the object was destroyed

CHANGELOG.md

@@ -4,6 +4,8 @@
   - [#383](https://github.com/airblade/paper_trail/pull/383) - Make gem compatible with `ActiveRecord::Enum` (available in `ActiveRecord` 4.1+).
   - [#373](https://github.com/airblade/paper_trail/pull/373) - Fix default sort order for the `versions` association in `ActiveRecord` 4.1.
   - [#372](https://github.com/airblade/paper_trail/pull/372) - Use [Arel](https://github.com/rails/arel) for SQL construction.
+  - [#365](https://github.com/airblade/paper_trail/issues/365) - `VersionConcern#version_at` should return `nil` when receiving a timestamp
+    that occured after the object was destroyed.
   - [#347](https://github.com/airblade/paper_trail/pull/347) - Autoload `ActiveRecord` models in via a `Rails::Engine` when
     the gem is used with `Rails`.
   - Expand `PaperTrail::VERSION` into a module, mimicking the form used by Rails to give it some additional modularity & versatility.

lib/paper_trail/has_paper_trail.rb

@@ -182,7 +182,8 @@ module PaperTrail
         # Because a version stores how its object looked *before* the change,
         # we need to look for the first version created *after* the timestamp.
         v = send(self.class.versions_association_name).subsequent(timestamp, true).first
-        v ? v.reify(reify_options) : self
+        return v.reify(reify_options) if v
+        self unless self.destroyed?
       end
 
       # Returns the objects (not Versions) as they were between the given times.

spec/models/widget_spec.rb

@@ -105,6 +105,21 @@ describe Widget do
         end
       end
 
+      describe :version_at do
+        it { should respond_to(:version_at) }
+
+        context "Timestamp argument is AFTER object has been destroyed" do
+          before do
+            widget.update_attribute(:name, 'foobar')
+            widget.destroy
+          end
+
+          it "should return `nil`" do
+            widget.version_at(Time.now).should be_nil
+          end
+        end
+      end
+
       describe :whodunnit do
         it { should respond_to(:whodunnit) }