Unit testing provides the developer with a number of methods called assertion methods:

#[test] 
fn multiply() 
{ 
   assert_eq!(5, 2 * 3); 
} 

In the preceding code snippet, we use the assert_eq! (assert equal) macro. The first argument is the answer expected, and the second argument is what is being tested. If 2 * 3 = 5, then the assertion is true and passes the unit test.