First go to AppHarbor (https://appharbor.com) and; just create an account with a free plan, since that should be fine for playing around with.

Follow the instructions on the AppHarbor website to create an application, but do not deploy your Nancy application yet.

Assuming that we are using MongoDB for the implementation of the IDataStore interface, add the MongoLab add-on to your AppHarbor application. This gives you access to a cloud-hosted MongoDB database that we will have our AppHarbor-hosted TodosNancy run against. If you have chosen another database for the data store, have a look through the AppHarbor add-ons—chances are there is an add-on for your type of database.

Go to the web.config file in TodosNancy and add the following line to the application settings section:

  <appSettings>
    <add key="webPages:Enabled" value="false" />
    <add key="MONGOLAB_URI" value="mongodb://localhost:27017/todos"/>
  </appSettings>

Then change the bootstrapper class to use this configuration value while connecting to the database as follows:

    protected override void ConfigureApplicationContainer(TinyIoCContainer container)
    {
      base.ConfigureApplicationContainer(container);

      var connectionString = ConfigurationManager.AppSettings.Get("MONGOLAB_URI");
      var mongoDataStore = new MongoDataStore(connectionString);
      container.Register<IDataStore>(mongoDataStore);
    }

For all the tests to still pass, add an app.config file to the TodosNancyTests project and add the corresponding settings to it:

<configuration>
  <appSettings>
    <add key="MONGOLAB_URI" value="mongodb://localhost:27017/todos"/>
  </appSettings>
</configuration>

The last piece missing before being ready to deploy this to AppHarbor is make sure the integration tests, that is, the tests in DocumentationTests and TodosModuleTest, are not run during the AppHarbor build and deploy pipeline. The reason for this is that we, on the one hand, want to take advantage of the fact that AppHarbor will run all unit tests it sees and only deploy if the tests pass, but on the other hand, we do not want to mess with setting up a test database on the cloud that can be used during test runs in AppHarbor. Note that if you use SQL Server for your data store, the xUnit AutoRollback attribute can be used to roll back changes made in tests. In real life scenarios (especially continuous delivery scenarios), though, you will probably want to do that test setup and have all the tests run in AppHarbor before deploying. To avoid running the integration tests on the cloud, first write an implementation of the ITestClassCommand interface in xUnit.net that only allows tests to run if they are running on a known developer machine and then apply it to the integration tests. The implementation is as follows:

  public class KnownDevMachinesOnly : ITestClassCommand
  {
    private TestClassCommand command;
    private ITypeInfo typeInf;

    public int ChooseNextTest(ICollection<IMethodInfo> testsLeftToRun)
    {
      return command != null ? command.ChooseNextTest(testsLeftToRun) : -1;
    }

    public Exception ClassFinish()
    {
      return command != null ? command.ClassFinish() : null;
    }

    public Exception ClassStart()
    {
      return command != null ? command.ClassStart() : null;
    }

    public IEnumerable<ITestCommand> EnumerateTestCommands(IMethodInfo testMethod)
    {
      return command != null ? command.EnumerateTestCommands(testMethod) : new ITestCommand[0];
    }

    public IEnumerable<IMethodInfo> EnumerateTestMethods()
    {
      return command != null ? command.EnumerateTestMethods() : new IMethodInfo[0];
    }

    public bool IsTestMethod(IMethodInfo testMethod)
    {
      return command != null ? command.IsTestMethod(testMethod) : false;
    }

    public object ObjectUnderTest
    {
      get { return command != null ? command.ObjectUnderTest : null; }
    }

    public ITypeInfo TypeUnderTest
    {
      get { return typeInf; }
      set
      {
        typeInf = value;
        if (KnowDevMachineNames.Contains(Environment.MachineName))
          command = new TestClassCommand(value);
      }
    }

    public IEnumerable<string> KnowDevMachineNames
    {
      get
      {
        yield return "HORSDAL";
        yield return "DEV2";
      }
    }
  }

Then apply it to the tests by adding an attribute that indicates to xUnit.net that it should use our custom KnownDevMachinesOnly class when trying to run the tests as shown in the following code:

  [RunWith(typeof(KnownDevMachinesOnly))]
  public class TodosModuleTests

  [RunWith(typeof (KnownDevMachinesOnly))]
  public class DocumentationTests

The only steps left now are to follow AppHarbors instructions on how to deploy the application. I will not repeat those here.