We have written our own integration test harness where we can write a number of \"operations\" or tests, such as \"GenerateOrders\". We have a number of parameters we can use t
Integration testing may be done at a user interface level (via automated functional tests - AFT) or service/api interface level.
There are several tools in both cases:
I have worked on projects that successfully used Sahi or Selenium for AFT of web apps, white for AFT for .NET WPF or winforms apps, swtBot for AFT of Eclipse Rich client apps and frankenstein for AFT of Java swing apps.
Fitnesse is useful for service/api level tests or for tests that run just below the UI. When done right, it has the advantage of having business-readable tests i.e. non-developers can read and understand the tests. Tools like NUnit are less useful for this purpose. SOAPUI is particularly suited for testing SOAP web services.
Factors to consider:
Some nuances are captured here.
Full disclosure: The author is associated with the organization behind most (not all) of the above free and open source tools.
You could try the Concordion framework for writing user acceptance tests in HTML files. It takes a BDD-style approach. There is a .Net port as well
It's not out of Beta yet, but StoryTeller looks promising: