[ActionMailer] Rename test/test_test to test/test_case_test
[ci skip] add line about text layout
AR#reset_column_information sometimes queries via table_exists?

so this assertion causes random test fail
MySQL: set connection collation along with the charset

Sets the connection collation to the database collation configured
in database.yml. Otherwise, `SET NAMES utf8mb4` will use the default
collation for that charset (utf8mb4_general_ci) when you may have chosen
a different collation, like utf8mb4_unicode_ci.

This only applies to literal string comparisons, not column values, so
it is unlikely to affect you.
Merge pull request #16752 from Shruti2791/shruti_workspace

[ci skip] add line about text layout
Merge pull request #16751 from seuros/rename

[ActionMailer] Rename test/test_test to test/test_case_test
After rack 1.6.0, by default, the rack will also out put the log which is not intent in rails.

Such change will also close the quiet_assets [issue 36](https://github.com/evrone/quiet_assets/issues/36) issue.