DB not being repopulated prior to Unit test execution


I’m working my way through the AWD book and have just started the
testing chapter. The first two unit tests run as expected. When I add
the test for the ‘destroy’ function to product_test.rb, however, I’m
getting a failure I don’t understand.

The error I’m getting says that in the setup method for test_update, it
“couldn’t find Product with ID=1”. When I run product_test.rb without
the test_destroy test case, the other two methods (test_create &
test_update) find that record fine. When I add the test_destroy case
in, though, it appears that the database isn’t being cleaned and
restored before the test_update method is executed (which appears in
this case to happen after the test_destroy method). At least, that’s
the only explanation I can come up with for what’s happening.

Any help understanding this will be very much appreciated.