Use `silence_warnings` on `StaticTests`

When 7e504927 was merged setting `Encoding.default_internal` and
`Encoding.default_external` would throw a warning when the ActionPack
tests were run.

Example warning: `actionpack/test/dispatch/static_test.rb:12: warning:
setting Encoding.default_external`

This patch silences the warnings as other similar tests do for setting
default_internal and default_external.

1 files changed, 12 insertions, 6 deletions

diff --git a/actionpack/test/dispatch/static_test.rb b/actionpack/test/dispatch/static_test.rb
index f153030675..93e5c85a97 100644
--- a/actionpack/test/dispatch/static_test.rb
+++ b/actionpack/test/dispatch/static_test.rb
@@ -3,13 +3,17 @@ require 'zlib'
 
 module StaticTests
   def setup
-    @default_internal_encoding = Encoding.default_internal
-    @default_external_encoding = Encoding.default_external
+    silence_warnings do
+      @default_internal_encoding = Encoding.default_internal
+      @default_external_encoding = Encoding.default_external
+    end
   end
 
   def teardown
-    Encoding.default_internal = @default_internal_encoding
-    Encoding.default_external = @default_external_encoding
+    silence_warnings do
+      Encoding.default_internal = @default_internal_encoding
+      Encoding.default_external = @default_external_encoding
+    end
   end
 
   def test_serves_dynamic_content
@@ -25,8 +29,10 @@ module StaticTests
   end
 
   def test_handles_urls_with_ascii_8bit_on_win_31j
-    Encoding.default_internal = "Windows-31J"
-    Encoding.default_external = "Windows-31J"
+    silence_warnings do
+      Encoding.default_internal = "Windows-31J"
+      Encoding.default_external = "Windows-31J"
+    end
     assert_equal "Hello, World!", get("/doorkeeper%E3E4".force_encoding('ASCII-8BIT')).body
   end