Visual Studio Unit tests: run initialization code before each test

Question

I'm using Visual Studio's Test Tools for unit testing. I need some initialization code to run before each test.

I have a Setup class for the initialization code. I already added code to run before each test run, using [AssemblyInitialize], but I can't figure out how to do the same on a single test basis.

I tried using the [TestInitialize] attribute, but this only applies to tests in the same file as the [TestInitialize] method. I would like the initialization code to run automatically for all tests in the assembly, without having to explicitly call it in each and every test file.

[TestClass]
public class Setup
{
    [AssemblyInitialize]
    public static void InitializeTestRun(TestContext context)
    {
        //... code that runs before each test run
    }

    [TestInitialize] //this doesn't work!
    public static void InitializeTest()
    {
        //... code that runs before each test
    }
}

There is no equivalent of `AssemblyInitialize` that runs for every test. I think you would have to base all your classes on a common base class to do that. What do you need to do in the initialisation? There may be another way. — stuartd, Jun 16 '16 at 15:18
Basically I'm mocking an Entity Framework context by using in memory dbsets, to avoid actually calling the real database. I'd like a fresh instance of a context for each test, i.e. a clean, empty 'db', so the tests do not interfere with eachother. — fikkatra, Jun 16 '16 at 15:36
I'm not sure there's a clean way of doing that, all your test files may have to have their own `TestInitialize` method which calls the db initialization. — stuartd, Jun 16 '16 at 15:40
Don't know MSTest enough but the following should work (at least it works with other test frameworks): Create a base class DatabaseIntegrationTests with the TestInitialize method. Derive your other Testclasses from that base class. — tobsen, Jun 17 '16 at 06:52
@tobsen if you convert your comment to an answer, I will accept it — fikkatra, Jul 04 '16 at 11:00

score 8 · Accepted Answer · answered Jul 05 '16 at 06:56

8

The following should work (at least it works with other test frameworks):

Create a base class DatabaseIntegrationTests with the TestInitialize method
Derive your other Testclasses from that base class

answered Jul 05 '16 at 06:56

tobsen

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score 7 · Answer 2 · answered Jun 16 '16 at 14:41

7

It is [TestInitialize] but you have the syntax wrong, it doesn't take a context:

[TestInitialize]
public static void InitializeTests()
{
    //... code that runs before each test
}

answered Jun 16 '16 at 14:41

stuartd

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I indeed got the syntax wrong (I will adjust it in the question), but sadly this doesn't solve the problem: TestInitialize does not apply to tests in another file – fikkatra Jun 16 '16 at 14:49
is the other file a partial file of the same class? IIRC the InitializeTests will only be run for all the tests of the surrounding class (in your case public class Setup) – tobsen Jun 16 '16 at 15:04
No it isn't. I have many test classes, but only a single Setup class. – fikkatra Jun 16 '16 at 15:40

Visual Studio Unit tests: run initialization code before each test

2 Answers2