Unit Testing the Use of TransactionScope

Question

The preamble: I have designed a strongly interfaced and fully mockable data layer class that expects the business layer to create a TransactionScope when multip

Answer 1

I found a great way to test this using Moq and FluentAssertions. Suppose your unit under test looks like this:

public class Foo
{
    private readonly IDataLayer dataLayer;

    public Foo(IDataLayer dataLayer)
    {
        this.dataLayer = dataLayer;
    }

    public void MethodToTest()
    {
        using (var transaction = new TransactionScope())
        {
            this.dataLayer.Foo();
            this.dataLayer.Bar();
            transaction.Complete();
        }
    }
}

Your test would look like this (assuming MS Test):

[TestClass]
public class WhenMethodToTestIsCalled()
{
    [TestMethod]
    public void ThenEverythingIsExecutedInATransaction()
    {
        var transactionCommitted = false;
        var fooTransaction = (Transaction)null;
        var barTransaction = (Transaction)null;

        var dataLayerMock = new Mock();

        dataLayerMock.Setup(dataLayer => dataLayer.Foo())
                     .Callback(() =>
                               {
                                   fooTransaction = Transaction.Current;
                                   fooTransaction.TransactionCompleted +=
                                       (sender, args) =>
                                       transactionCommitted = args.Transaction.TransactionInformation.Status == TransactionStatus.Committed;
                               });

        dataLayerMock.Setup(dataLayer => dataLayer.Bar())
                     .Callback(() => barTransaction = Transaction.Current);

        var unitUnderTest = new Foo(dataLayerMock.Object);

        unitUnderTest.MethodToTest();

        // A transaction was used for Foo()
        fooTransaction.Should().NotBeNull();

        // The same transaction was used for Bar()
        barTransaction.Should().BeSameAs(fooTransaction);

        // The transaction was committed
        transactionCommitted.Should().BeTrue();
    }
}

This works great for my purposes.