Add some interface tests

Fortunately there were no errors found on interfaces, but it's good to
have the test to avoid any future breaks.

Change-Id: I073a9cff82581a0a53470e949f6b399af0212e87
Try to use locale_name + '.UTF-8' if it wasn't found

Change-Id: Id720e0a7e383b5dc100e060d8db928b318c6f258
Add some tests for datatypes

Change-Id: I1c2d576517ac8cb8fe947c1b7d6903243d378da5