Fix deprecation warning in tests

Using the string version of the class reference is now deprecated when
referencing middleware. This should be written as a class not as a string.

Deprecation warning that this change fixes:
```
DEPRECATION WARNING: Passing strings or symbols to the middleware
builder is deprecated, please change
them to actual class references.  For example:
  "ActionDispatch::ShowExceptions" => ActionDispatch::ShowExceptions
```

1 files changed, 7 insertions, 7 deletions

diff --git a/actionview/test/abstract_unit.rb b/actionview/test/abstract_unit.rb
index 4635c645d0..35f520ed1c 100644
--- a/actionview/test/abstract_unit.rb
+++ b/actionview/test/abstract_unit.rb
@@ -147,13 +147,13 @@ class ActionDispatch::IntegrationTest < ActiveSupport::TestCase
 
   def self.build_app(routes = nil)
     RoutedRackApp.new(routes || ActionDispatch::Routing::RouteSet.new) do |middleware|
-      middleware.use "ActionDispatch::ShowExceptions", ActionDispatch::PublicExceptions.new("#{FIXTURE_LOAD_PATH}/public")
-      middleware.use "ActionDispatch::DebugExceptions"
-      middleware.use "ActionDispatch::Callbacks"
-      middleware.use "ActionDispatch::ParamsParser"
-      middleware.use "ActionDispatch::Cookies"
-      middleware.use "ActionDispatch::Flash"
-      middleware.use "Rack::Head"
+      middleware.use ActionDispatch::ShowExceptions, ActionDispatch::PublicExceptions.new("#{FIXTURE_LOAD_PATH}/public")
+      middleware.use ActionDispatch::DebugExceptions
+      middleware.use ActionDispatch::Callbacks
+      middleware.use ActionDispatch::ParamsParser
+      middleware.use ActionDispatch::Cookies
+      middleware.use ActionDispatch::Flash
+      middleware.use Rack::Head
       yield(middleware) if block_given?
     end
   end