Missing number of assertions in test output


I did a number of test runs from the book Agile Web Development with Rails, third edition, (chapter 14, Task T: Testing).

I use Netbeans 6.8 as IDE.

All the test output runs are missing the number of assertions. For example:

       Finished in 0,733 seconds.
5 tests, 0 failures, 0 errors

However in this example, 6 assertions were tested and I expected:

       Finished in 0,733 seconds.
5 tests, 6 assertions, 0 failures, 0 errors

Can anyone give me a clue why the assertions are missing in the output?

Thanks in advance,