Pass the correct value as JSON

This takes away the following log.

```
Error occurred while parsing request parameters.
Contents:

{:foo=>"heyo"}
```
Pass the correct value as JSON

1 files changed, 1 insertions, 1 deletions

diff --git a/actionpack/test/controller/test_case_test.rb b/actionpack/test/controller/test_case_test.rb
index bc64135589..d1cd190747 100644
--- a/actionpack/test/controller/test_case_test.rb
+++ b/actionpack/test/controller/test_case_test.rb
@@ -988,7 +988,7 @@ XML
   end
 
   def test_parsed_body_with_as_option
-    post :render_json, body: { foo: "heyo" }, as: :json
+    post :render_json, body: { foo: "heyo" }.to_json, as: :json
     assert_equal({ "foo" => "heyo" }, response.parsed_body)
   end
 end