1. Quality Assurance is not Quality Insurance
Looking back over the years, we can see that projects tend to use test efforts as Quality Insurance, rather than a part of the Quality Assurance efforts. Having well-designed test cases exercising relevant functionality from different perspectives are, of course, fundamental. If done right, it is probably the best way to determine if deliverables are designed to specification. This cannot, however, be viewed as an insurance policy put on the development process against any errors introduced along the way.