Fix test cases for inflector.rb
`yield` was missing in #with_dup, due to which 57 assertions were not running
in real, and all tests were passing by default.
Error was introduced in commit - 31ceb5e.
Remove duplicated to_s method call.
Merge pull request #15316 from akshay-vishnoi/test-cases

Fix test cases for inflector.rb
Merge pull request #15325 from tgxworld/no_need_to_call_to_s

Remove duplicated to_s method call.
pg, remove unused code. Use `extract_schema_and_table` instead.
pg, add missing `:nodoc:` to adapter.
Add an interface for type objects to control Ruby => SQL

Adds the ability to save custom types, which type cast to non-primitive
ruby objects.
Merge pull request #15307 from sgrif/sg-type-cast-for-write

Add an interface for type objects to control Ruby => SQL