!3 This is primarily necessary to test Fitnesse itself. We need the ability to show that Fitnesse will correctly fail a test when comparing different expected and actual values, but we need that test to turn GREEN so we don't have failing tests!

Works for primatives
|int fixture|
|field|field?|
|21|fail[37]|

Works for strings
|string fixture|
|field|field?|
|some value|fail[some other value]|

Works for objects (people)
|person fixture|
|field|field?|
|Joe Smith|fail[Joe Smithe]|

You can even use the fail keyword to prove that the fail keyword works. In this test, we wrap "fail[Joe Smith]" inside a fail - so when the application returns a person named "Joe Smith", which fails to fail (get it?), the test PASSES!
|person fixture|
|field|field?|
|Joe Smith|fail[fail[Joe Smith]]|

And this one shows that "Joe Smith" (correctly) does not equal "failure[Joe Smith]"
|person fixture|
|field|field?|
|Joe Smith|fail[failure[Joe Smith]]|