mono/doc/testing

* Testing 

	All classes in Mono libraries should have comprehensive unit test
	suites to go with them. Unit testing is a software engineering
  	methodology that makes it easier to build correct code. Every
  	method in every class should have a set of tests to verify
  	that they work correctly. Mono also needs a testing framework
	to make it easy to write and run lots of tests. 

	Try <a href="http://nunit.sourceforge.net">NUnit</a>

	Why do unit testing? It becomes simple to run automated tests
	for the whole library. Unit tests are a safety net - you can
	change part of the code and verify that you haven't broken
	anything. Ideally, tests are written before the actual library
	code itself. And every time a bug is discovered, a test should
	be written to demonstrate the bug and its fix. Then, if
	you ever reintroduce the bug, you will know immediately. For
	more info, read <a
	href="http://nunit.sourceforge.net/doc/testinfected/testing.html">
	JUnit Test Infected: Programmers Love Writing Tests</a>.