Many teams claim they do agile testing but not many do it right. Blake Norrish put together a really good list of common anti-patterns that occur fairly often (unfortunately).
I love the way Maaret Pyhäjärvi explained the relationship with testing varying on the point of view. So simple and so true.
Additionally, James Thomas gives a great example of how to ask the right questions in Mass Testing.
This is an amazing, thought-provoking article from Daniel Terhorst-North — the inventor of BDD with 30 years of experience in software development — discussing what testing is, what it isn't, and what practices such as TDD, BDD and ATDD have to do with testing.