Enabled quirks mode on JSON.parse, fixes broken test in af9caae

It turns out that ActionPack depends on the decoder to parse JSON
"fragments" (e.g. '"a string"', '1', 'null', etc), so we need to
enable quirks mode on JSON.parse. Also added coverage on the decoder
side to prevent regression.

2 files changed, 14 insertions, 2 deletions

diff --git a/activesupport/lib/active_support/json/decoding.rb b/activesupport/lib/active_support/json/decoding.rb
index 2533ff43e1..21de09c1cc 100644
--- a/activesupport/lib/active_support/json/decoding.rb
+++ b/activesupport/lib/active_support/json/decoding.rb
@@ -14,7 +14,7 @@ module ActiveSupport
       #   ActiveSupport::JSON.decode("{\"team\":\"rails\",\"players\":\"36\"}")
       #   => {"team" => "rails", "players" => "36"}
       def decode(json, options = {})
-        data = ::JSON.parse(json, options.merge(create_additions: false))
+        data = ::JSON.parse(json, options.merge(create_additions: false, quirks_mode: true))
         if ActiveSupport.parse_json_times
           convert_dates_from(data)
         else
diff --git a/activesupport/test/json/decoding_test.rb b/activesupport/test/json/decoding_test.rb
index 3ec9b06d6a..e9780b36e4 100644
--- a/activesupport/test/json/decoding_test.rb
+++ b/activesupport/test/json/decoding_test.rb
@@ -59,7 +59,16 @@ class TestJSONDecoding < ActiveSupport::TestCase
     %q({"a":"\n"})  => {"a"=>"\n"},
     %q({"a":"\u000a"}) => {"a"=>"\n"},
     %q({"a":"Line1\u000aLine2"}) => {"a"=>"Line1\nLine2"},
-    %q({"json_class":"TestJSONDecoding::Foo"}) => {"json_class"=>"TestJSONDecoding::Foo"}
+    # prevent json unmarshalling
+    %q({"json_class":"TestJSONDecoding::Foo"}) => {"json_class"=>"TestJSONDecoding::Foo"},
+    # json "fragments" - these are invalid JSON, but ActionPack relies on this
+    %q("a string") => "a string",
+    %q(1.1) => 1.1,
+    %q(1) => 1,
+    %q(-1) => -1,
+    %q(true) => true,
+    %q(false) => false,
+    %q(null) => nil
   }
 
   TESTS.each_with_index do |(json, expected), index|
@@ -83,7 +92,10 @@ class TestJSONDecoding < ActiveSupport::TestCase
   end
 
   def test_failed_json_decoding
+    assert_raise(ActiveSupport::JSON.parse_error) { ActiveSupport::JSON.decode(%(undefined)) }
+    assert_raise(ActiveSupport::JSON.parse_error) { ActiveSupport::JSON.decode(%({a: 1})) }
     assert_raise(ActiveSupport::JSON.parse_error) { ActiveSupport::JSON.decode(%({: 1})) }
+    assert_raise(ActiveSupport::JSON.parse_error) { ActiveSupport::JSON.decode(%()) }
   end
 
   def test_cannot_force_json_unmarshalling