A nice side effect of the Pex infrastructure is that it computes coverage data while exploring a parameterized test. What does this mean to the user? Well, what about this specifying that a parameterized test should reach 100% coverage**:

[PexTest]
[PexExpectedCoverage(100)] // expect 100% coverage
public void UberTest(int i)
{ ... }

** What kind of coverage are we talking about?

Pex internally tracks implicit branch coverage (which can never be covered :)). So we usually refer to basic block coverage. By default, the coverage is reported for the code that was run by the parameterized test. This is a very important difference with usual coverage tools, which give numbers for the entire assembly.