Enables unit tests to be written like so:

[Test]
public void GivenASearch_WhenItCompletes()
{
  Scenario
    .Given(ASearchResultsStateObjectThatIsSearching)
    .Then(UserInterfaceShowsBusyIndicator)
    .When(SearchCompletes)
    .Then(UserInterfaceDoesNotShowBusyIndicator)
    .And(TotalResultCountIs, 600)
    .And(IncludedResultCountIs, 500)
    .Execute();
}