OO Design and testing

Question

Hi there,
If one has a private variable and a public "setter" method in a class how would one go about testing this "setter"? Like to test if a particular object was actually set it would require a public "getter" which is exposing implementation.
Would it be best then to infer the validitity of the "setter" indirectly through testing another public business level method?
Regards,
James.

Answer 1

excerpt from JUnit in Action, 3.3 (p.56) :
JUnit best practices: test anything that could possibly fail
Unit tests help ensure that your methods are keeping their API contracts with
other methods. If the contract is based solely on other components� keeping
their contracts, then there may not be any useful behavior for you to test. But
if the method changes the parameter�s or field�s value in any way, then you
are providing unique behavior that you should test. The method is no longer
a simple go-between�it�s a filtering or munging method with its own behavior
that future changes could conceivably break. If a method is changed so it
is not so simple anymore, then you should add a test when that change takes
place, but not before. As the JUnit FAQ puts it, �The general philosophy is this:
if it can�t break on its own, it�s too simple to break.�
But what about things like JavaBean getters and setters? Well, that depends. If
you are coding them by hand in a text editor, then yes, you might want to test
them. It�s surprisingly easy to miscode a setter in a way that the compiler
won�t catch. But if you are using an IDE that watches for such things, then
your team might decide not to test simple JavaBean properties.
A good piece of advice to make your mind about all this ;-)