I must confess, i never read the original book/paper, just about it from various sources. I was under the impression that in "proper" TDD you always try and write the test first; so as not to taint your tests with un-necessary implementation details

In my steps above, i was switching the order in between 3 and 4. Adding logic to "thing" first and then updating the test to match; mocking and patching my way across. So implementation first and tests later. Lazy TDD as another commenter mentioned.