Re: Need help designing some JUnit tests
Tom Anderson wrote:
On Thu, 20 May 2010, Rhino wrote:
But the same situation applies to things that aren't based on
convenience methods. A list of telephone area codes or the names of
all chiropractors in Ohio or any of a thousand other results from
methods are also "moving targets". I'm really not sure how to test those.
These methods get their answers from some source of data, right?
So the way you test them is with test data. Rather than plugging the
code into the real data, you make a controlled set of test data, plug
them into that, and test that they behave in the way you would expect
given the test data. You then assume that they'll behave the right way
when plugged into real data.
Naturally, this means structuring your code so that it can easily be
plugged into different sources of data. This is probably a good thing
anyway.
This is the other side of the principle I was advocating in another
subthread, making an output method use a PrintStream that is either a
method parameter or provided when its object is constructed, rather than
writing to e.g. System.out.
I feel that test driven design, by encouraging separation of the details
of data input and output processing from the choice of data source or
sink, leads to better structured, more flexible code.
Patricia