Test that a DateTime acts_like_date
Missing AS::Deprecation::DeprecatedObjectProxy test
Test that DeprecatedConstantProxy does not warn when accessing its class
Test try! with a block
Test Kernel#quietly
Test that rescue_from accepts a class name in String
Test String#dasherize
Fix some wrong String extensions tests

* ASCII_STRING was not an ASCII String
* BYTE_STRING was not an in valid UTF-8 String
* added an assertion for non-UTF-8 String
A test case name needs to start with "test_"