I read this and do not consider it to be about "the importance of software testing"... it reads more like a demonstration of the hubris that one can fix a fundamentally flawed system by trying to dream up test cases and then fixing them one by one as if they were in isolation of each other. One can imagine someone writing something like this about a sorting algorithm, slowly discovering corner cases of large numbers, negative numbers, 2s compliment wraparound situations, custom comparators that violate invariants, values that are being mutated while sorting... the more of these issues you find the more you should question that you really have defined the problem correctly, not patting yourself on the back for having good testing.
