Add note about calling parent::setUp()

[jdietrch]

Note: This is a copy of sebastianbergmann/phpunit-documentation#236

After adding a setUp() method to my database testing class, the database initialization process wasn't happening properly anymore.This seems to be the same problem that was asked and answered here:
http://stackoverflow.com/questions/9490397/dbunit-in-phpunit-is-not-truncating-the-tables

So I added parent::setUp(); as the first line of my setUp() method, and it's working again.
It would be helpful if the phpunit documentation would make it clear that it is important to call parent::setUp() when overriding the setUp() method, in at least some conditions.

It should probably be mentioned in chapter 4 "Fixtures" where it talks about the setUp() method. Perhaps something like: "If you do override setUp(), don't forget to begin with a call to parent::setUp() if this or that condition applies. Otherwise, this or that thing won't happen anymore, with these undesireable results."

And it should probably also be mentioned somewhere in chapter 8 "Database Testing". Perhaps something like: "If you override setUp() as described in chapter 4, be sure to call parent::setUp(), for this and that reason. Otherwise, this or that other thing won't happen, with these undesireable results.

Of course, if one should always start setUp() with a call to parent::setUp(), a short note to that effect in the appropriate place(s) could save those who don't know or remember to do this some time and frustration.

[sebastianbergmann]

Closing as the chapter in question has been removed from the documentation (and DbUnit is no longer supported).