Question

One of my unit tests seems to randomly pass or fail when I run it. The only thing that makes sense to me for why this is happening is if the data in the database is getting into a different state each time the test is ran, but I use transactions to rollback the database in each test – unless it’s not working right. Here’s my base unit test class and the unit test class that’s having the problem. Can you see anything I might be missing or what else I should look for?

This happens with TestDriven.Net and the Visual Studio Unit Test Framework.

Partial Public MustInherit Class TestBase

    Private _scope As Transactions.TransactionScope

    <DebuggerStepThrough()> _
    <TestInitialize()> _
    Public Sub Setup()

            //'Start the Distribution Transaction Coordinator, if it's not already running.
            Using dtcService As New System.ServiceProcess.ServiceController("Distributed Transaction Coordinator", My.Computer.Name)
                    If dtcService.Status = ServiceProcess.ServiceControllerStatus.Stopped Then
                            dtcService.Start()
                    End If
            End Using

            _scope = New TransactionScope(TransactionScopeOption.RequiresNew, New TimeSpan(0))
    End Sub

    <DebuggerStepThrough()> _
    <TestCleanup()>
    Public Sub Teardown()
        If _scope IsNot Nothing Then
            _scope.Dispose()
        End If
    End Sub

    <System.Diagnostics.DebuggerStepThrough()> _
    Public Shared Function ExecSql(ByVal sql As String) As System.Data.DataTable

        Dim connStr = GlobalSettings.GetConnectionString()
        Using conn As New System.Data.SqlClient.SqlConnection(connStr)
            conn.Open()

            Dim cmd As New System.Data.SqlClient.SqlCommand(sql.ToString, conn)
            Dim adapter As System.Data.SqlClient.SqlDataAdapter = New System.Data.SqlClient.SqlDataAdapter(cmd)
            Dim dt As System.Data.DataTable = New System.Data.DataTable
            adapter.Fill(dt)

            Return dt

            If conn.State <> System.Data.ConnectionState.Closed Then
                conn.Close()
            End If
            conn.Dispose()
        End Using
    End Function
End Class

And here’s my unit test:

Partial Public Class CampaignEmailSendLimitServiceTests
    Inherits TestBase

    Private _service = ServiceManager.Current.MyService

    <TestMethod()> _
    Public Sub MyTest()
        //' Set the pre-test condition.
        ExecSql("update base.dbo.tblTableA set someDate = '2010-06-28' where id = 56937 ")

        //' Run the service
        _service.Process()

       //' Verify the expected result
       Dim dt = ExecSql("select deliveryDate from tblTableB ")
       Assert.AreEqual(False, dt.Rows(0).IsNull("deliveryDate"))

    End Sub
End Class

Answer 1

I finally figured out what was going on. It had nothing to do with transactions. That’s all working great. It was my process that was creating inconsistent behavior – by design. There was a part of the process that had a “random ranking” to determine the deliveryDate if no other rankings where found. The unit test needs to be rewritten to better reflect the business rules.