mono/doc/testing

* Testing

	Testing is an important part of the Mono project: every one of its
	three major components has a test suite tailored for its needs.  This
	is very helpful, because in the course of developing the software it
	is very common to introduce bugs in existing code.  A test suite
	helps us fix the bugs as soon as they are introduced.

** Class Library Tests

	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. 


** Getting started

	If you are new to writing NUnit tests, there is a template you may use
	to help get started. The file is:

		<b>mcs/class/doc/TemplateTest.cs</b>

	Save a copy of this file in the appropriate test subdirecty
	(see below), and replace all the [text] markers with
	appropriate code. Comments in the template are there to guide
	you. You should also look at existing tests to see how other
	people have written them.
	mcs/class/corlib/Test/System.Collections/CollectionBaseTest.cs
	is a small one that might help.

	The directory that will contain your new file depends on the
	assembly/namespace of the class for which you are creating the
	tests.  Under mcs/class there is a directory for each
	assembly. In each assembly there is a Test directory,
	e.g. mcs/class/corlib/Test. In the Test directory there are
	sub-directories for each namespace in the assembly,
	e.g. mcs/class/corlib/Test/Sytem. Put your new test file in
	the appropriate sub-directory under Test for the class you are
	testing.
	
	Once your test class is complete, you need to add it to the
	AllTests.cs file in the same directory as your new test. Add a
	call to "suite.AddTest()" passing the name of your new test
	class's suite property as the parameter.  You will see
	examples in the AllTests.cs file, so just copy and paste
	inside there.
	
	Once all of that is done, you can do a 'make test' from the top mcs
	directory.  Your test class will be automagically included in the
	build and the tests will be run along with all the others.

* Tips on writing Unit tests.

	You should look at the NUnit documentation, as it is a
	fantastic product, and includes fantastic documentation, but
	here are some tips for those of you who are already reading
	this web page.


** Provide an unique error message for Assert()

	Include an unique message for each Assert() so that when the assert
	fails, it is trivial to locate the failing one. Otherwise, it may be
	difficult to determine which part of the test is failing. A good way
	to ensure unique messages is to use something like #A01, #A02 etc.

	    Ok:
	<pre>
	
		AssertEquals("array match", compare[0], i1[0]);
		AssertEquals("array match", compare[1], i1[1]);
		AssertEquals("array match", compare[2], i1[2]);
		AssertEquals("array match", compare[3], i1[3]);
	</pre>

	    Excellent:
	<pre>
		AssertEquals("#A01", compare[0], i1[0]);
		AssertEquals("#A02", compare[1], i1[1]);
		AssertEquals("#A03", compare[2], i1[2]);
		AssertEquals("#A04", compare[3], i1[3]);
	</pre>
	
	Once you used such a number in an Assert(), don't change it later on -
	people might use it it identify the test in bug reports or in mailing
	lists.

** Use AssertEquals() to compare things, not Assert().

	Do not compare two values with Assert() - if the test fails,
	people have no idea what went wrong while AssertEquals()
	reports the failed value.

	Ok:
	<pre>
	        Assert ("A01", myTicks[0] == t1.Ticks);
	</pre>

	Excellent:
	<pre>
	        AssertEquals ("A01", myTicks[0], t1.Ticks);
	</pre>

** Constructors

	When writing your testcase, please make sure to provide a constructor
	which takes no arguments:

	<pre>
        public class DateTimeTest : TestCase
        {

                public DateTimeTest() : base ("[MonoTests.System.DateTimeTest]") {}
                public DateTimeTest (string name): base(name) {}

        	public static ITest Suite
                {
                        get {
                                TestSuite suite = new TestSuite ();
        			return suite;
        		}
        	}
        }
	</pre>

** Namespace

	Please keep the namespace within each test directory consistent - all
	tests which are referenced in the same AllTests.cs must be in the same
	namespace. Of course you can use subnamespaces as you like -
	especially for subdirectories of your testsuite.
	
	For instance, if your AllTests.cs is in namespace "MonoTests" and you
	have a subdirectory called "System", you can put all the tests in that
	dir into namespace "MonoTests.System".
	
** Test your test with the Microsoft runtime
	
	If possible, try to run your testsuite with the Microsoft runtime on
	Windows and make sure all tests in it pass. This is especially
	important if you're writing a totally new testcase - without this
	check you can never be sure that your testcase contains no bugs ....
	
	Don't worry if you're writing your test on Linux, other people can
	test it for you on Windows.
	
	Sometimes you may discover that a test doesn't show the expected
	result when run with the Microsoft runtime - either because there is a
	bug in their runtime or something is misleading or wrong in their
	documentation. In this case, please put a detailed description of the
	problem to mcs/class/doc/API-notes and do also report it to the list -
	we'll forward this to the Microsoft people from time to time to help
	them fix their documentation and runtime.

** Unit tests.

	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://junit.sourceforge.net/doc/testinfected/testing.htm">
	JUnit Test Infected: Programmers Love Writing Tests</a>.


** Getting Started

	We welcome all contributions to the Class Libary Test Suite.

	There is information to help you get started in CVS at
	mcs/class/doc/NUnitGuidelines. Once you have written your test, please
	post it to <a href="mailing-lists.html">mono-list</a>.

	Someone will make sure to add the file or apply the patch as
	appropriate. If you plan to be an on-going contributor and
	would like to get cvs account, email <a href="mailto:[email protected]">miguel</a>.

	Normally, after you send a couple of well-written new files
	and/or patches to the list, you will be given cvs access.