Order of execution of unit tests in Visual Studio 2008

I have unit tests defined for my Visual Studio 2008 solution. These tests are defined in multiple methods and in multiple classes across several files.

I've read in a blog articl开发者_StackOverflowe that when using MSTest, it is a mistake to think that you can depend on the order of execution of your tests:

Execution Interleaving: Since each instance of the test class is instantiated separately on a different thread, there are no guarantees regarding the order of execution of unit tests in a single class, or across classes. The execution of tests may be interleaved across classes, and potentially even assemblies, depending on how you chose to execute your tests. The key thing here is – all tests could be executed in any order, it is totally undefined.

That said, I have to have a pre-execution step before any of these tests gets to run. That is, I actually want to define an order of execution somehow. For example, 1) first create the database; 2) test that it's created; then 3) run the remaining 50 tests in arbitrary order.

Any ideas on how I can do that?

I wouldn't test that the database is successfully created; I will assume that all subsequent tests will fail if it is not, and it feels in a way that you would be testing the test code.

Regarding a pre-test step to set up the database, you can do that by creating a method and decorating it with the ClassInitialize attribute. That will make the test framework execute that method prior to any other method within the test class:

[ClassInitialize()]
public static void InitializeClass(TestContext testContext) 
{ 
    // your init code here
}

Unit tests should all work standalone, and should not have dependencies on each other, otherwise you can't run a single test in isolation.

Every test that needs the database should then just create it on demand (if it's not already been created - you can use a singleton/static class to ensure that if multiple tests are executed in a batch, the database is only actually created once).

Then it won't matter which test executes first; it'll just be created the first time a test needs a database to use.

In theory it is correct that tests should be independent of each other and be able to run standalone. But in practice, there is a difference between theory and practice, and VS2010 gives me a hard time with its fixed order of execution (random order that is always the same).

Here are some examples:
I have a unit test that cross checks the dates between some tables and verifies that everything is in agreement. Obviously it is of no use to run this test on an empty database, so I want to to run SOME TIME AFTER the unit test that inserts data. Sorry VS2010 doesn't let you do this.
OK, cool, then I will add it to the insert unit test as an epilogue. But then I want to cross check other 10 things and instead of having a unit test ("Make sure that entities with various parameters can be inserted without crashes") I end up having a mega-test.

Then another case.
My unit test inserts entities, just insert, to make sure that this part of the logic works ok. Then I have a multi-threaded version of the test, to make sure that there are no deadlocks and stuff. Clearly I need the multi-threaded test to run SOME TIME AFTER the single threaded test, and ONLY if the single threaded test succeeds. Sorry, VS2010 can't do this.

Another case. I have a unit test that deletes ALL entities of a given kind in the database. This should result in a bunch of empty tables and lots of zeros in other tables. Clearly it is useless to run it on an empty database, so the test inserts 10.000 entities if it finds the DB empty. However, if it runs AFTER the multithreaded test, it will find 250.000 entities, and to delete ALL of them takes TIME. Sorry, VS2010 won't let me do anything about it.

The funny thing is that because of this situation my unit tests started slowly turning into mega-tests, that took more than 30 mins to complete (each) and then VS2010 would time them out, cause the default test timeout is 30 mins. OMG please help! :-)