what kind of testing in object oriented code example

Example: how is testing object oriented design

Well-engineered object-oriented design can
make it easier to trace from code to internal
design to functional design to requirements.
While there will be little affect on black box 
testing (where an understanding of the internal
design of the application is unnecessary), 
white-box testing can be oriented to the
application's objects. If the application was
well-designed this can simplify test design.