Do not expose internal state in the public encoder API (i.e. as_json)

See [1] for why this is not a good idea.

As part of this refactor, circular reference protection in as_json has
been removed and the corresponding error class has been deprecated.

As discussed with @jeremy, circular reference error is considered
programmer errors and protecting against it is out of scope for
the encoder.

This is again based on the excellent work by @sergiocampama in #11728.

[1]: https://github.com/intridea/multi_json/pull/138#issuecomment-24468223

1 files changed, 9 insertions, 3 deletions

diff --git a/activesupport/test/json/encoding_test.rb b/activesupport/test/json/encoding_test.rb
index 99120f1d2a..11a2ca9d90 100644
--- a/activesupport/test/json/encoding_test.rb
+++ b/activesupport/test/json/encoding_test.rb
@@ -146,19 +146,25 @@ class TestJSONEncoding < ActiveSupport::TestCase
   def test_exception_raised_when_encoding_circular_reference_in_array
     a = [1]
     a << a
-    assert_raise(ActiveSupport::JSON::Encoding::CircularReferenceError) { ActiveSupport::JSON.encode(a) }
+    assert_deprecated do
+      assert_raise(ActiveSupport::JSON::Encoding::CircularReferenceError) { ActiveSupport::JSON.encode(a) }
+    end
   end
 
   def test_exception_raised_when_encoding_circular_reference_in_hash
     a = { :name => 'foo' }
     a[:next] = a
-    assert_raise(ActiveSupport::JSON::Encoding::CircularReferenceError) { ActiveSupport::JSON.encode(a) }
+    assert_deprecated do
+      assert_raise(ActiveSupport::JSON::Encoding::CircularReferenceError) { ActiveSupport::JSON.encode(a) }
+    end
   end
 
   def test_exception_raised_when_encoding_circular_reference_in_hash_inside_array
     a = { :name => 'foo', :sub => [] }
     a[:sub] << a
-    assert_raise(ActiveSupport::JSON::Encoding::CircularReferenceError) { ActiveSupport::JSON.encode(a) }
+    assert_deprecated do
+      assert_raise(ActiveSupport::JSON::Encoding::CircularReferenceError) { ActiveSupport::JSON.encode(a) }
+    end
   end
 
   def test_hash_key_identifiers_are_always_quoted