Trappings is a convenient way to setup integration tests with MongoDB. You define reusable sets of data (fixtures) that will also be cleaned out at the end of a test.

Define Fixtures

The cleanest way to setup a fixture is to create a class that implements ITestFixtureData:

class TheRaceTrack : ITestFixtureData
{
  // A convenient pattern to follow is to make static properties for things
  // you'll access within the test. All of these are completely valid within
  // the using block.
  public static Car Cruze { get; set; }

  public IEnumerable<SetupObject> Setup() 
  {
    // Assign to static field for easy access later
    Cruze = new Car { Make = "Chevy", Model = "Cruze" };

    // cruze will be inserted into the database after this line
    yield return new SetupObject { CollectionName = "cars", Value = Cruze };

    // Since `cruze` has already been inserted, it's ID is already auto-assigned
    var tim = new Driver { Name = "Tim", CarId = Cruze.Id };
    yield return new SetupObject("drivers", tim);
  }
}

Each item that is yielded into the Enumerable is immediately inserted into the database. This is useful (as above) for setting up relationships between collections. It's also sometimes useful to hold a reference to objects created in a static property or field - so you can access them during tests for verifying behavior.

Using fixtures from a test

[Test]
public void ILoveCars()
{
  using(FixtureSession.Create<TheRaceTrack>())
  {
    // Database is now setup. You can use code that assumes that documents
    // exist in db.cars and db.drivers

    var driver = from driver in drivers.AsQueryable()
                 where driver.CarId == TheRaceTrack.Cruze.Id
                 select driver;

    driver.Count().ShouldEqual(1);
  }
  // objects from TheRaceTrack are no longer accessible in Mongo
}

You can use this for inter-process tests -- like functional or regression tests that hit a website or web service.

Building

• Install Visual Studio Visualization and Modeling SDK. This is required for the T4 templates. The project won't build without it.
• Open Trappings.sln in Visual Studio 2010.
• Build!

To build the NuGet package, you have to use the rakefile:

• Install Ruby
• run gem install rake albacore
• cd into the root of your checkout root
• run rake package