Conventional wisdom says that 100% code coverage is unnecessary, even undesirable, because achieving it requires spending an exceedingly large amount of time writing code not for the purpose of asserting correctness, but instead for the sole purpose of achieving coverage. In other words, it is often said that 100% code coverage has no business value.
Let me tell you why this is wrong, and why 100% code coverage can indeed be a very good thing to have.