I agree with the general approach suggested in the article (in tests, write/assume the code you wish you had).
But one detail ran counter to my personal practice.
I don't believe that "symmetrical" unit tests are a worthy goal. I believe in testing units of behavior, whether or not they correspond to a method/class. Symmetry leads to brittleness. I refactor as much as possible into private methods, but I leave my tests (mostly) alone. I generally try to have a decent set of acceptance tests, too.
Ideally, you specify a lot of behavior about your public API, but the details are handled in small private methods that are free to change without affecting your tests.
But one detail ran counter to my personal practice.
I don't believe that "symmetrical" unit tests are a worthy goal. I believe in testing units of behavior, whether or not they correspond to a method/class. Symmetry leads to brittleness. I refactor as much as possible into private methods, but I leave my tests (mostly) alone. I generally try to have a decent set of acceptance tests, too.
Ideally, you specify a lot of behavior about your public API, but the details are handled in small private methods that are free to change without affecting your tests.