Expanding on the previous post about how much testing may be too much, they're back with another post in the series, this time focusing on the "economy of tests". This time Mathias is joined by Konstantin Kudryashov as a co-author.

A common complaint with teams that first try their hand at automated testing, is that it is hard, costly, and not worth the effort. On the other hand, supporters say that it saves them time. In this post, we'll try to add some nuance to the discussion. We'll take a look at how different levels of automated testing affect the cost of development, both in the short and the long term, for both greenfield and brownfield projects. Finally, we'll look at a simple strategy for introducing tests and migrating them across test levels, in order to reduce maintenance costs.

They start with some baseline definitions so everyone's on the same page - unit test, integration testing and system testing. The article also covers some of the basic kinds of testing metrics including execution speed, fragility and understandability. It then moves on and looks at the other major final factor in the overall cost of testing, the age of the project (new vs existing). He mentions the Testing Pyramid, how it's recommended to migrate tests and some of the common opposing forces to the test migration/creation.