Unit testing - suitable for all development?

[Kylotan]

Today I tried to implement some sort of unit testing into my program
for the first time, and must admit to being a little disillusioned
with the process. Mainly, my issue is that in my program, the classes
are so tightly coupled that testing in isolation is next to
impossible.

The main problem stems from the fact that I try to ensure that all my
objects are created in a working state. This often means passing
various other objects to the __init__ function. In turn, these other
objects rely on others, and on general initialisation procedures. The
end result is that there are very few objects I can truly test in
isolation; I have to initialise at least 80% of the system before I
can even create most of my objects. This ends up meaning that unit
testing isn't really testing a single unit at all, and in fact isn't
much more precise than liberally using asserts in the normal code.

One way out of this would be to reduce coupling. This would allow me
to test objects in relative isolation, but it would increase the
amount of explicit coupling code that I'd have to execute normally.
This extra code then becomes a potential source of new bugs.

Has anybody else come to similar conclusions?

-- 
Ben Sizer