Gary Bernhardt

An exploration of the boundaries between pieces of code, including: isolated testing, behavior vs. data, mutation vs. immutability, how data shape affords parallelism, transforming interface dependencies into data dependencies, and what it might look like to build systems using all of these to guide the boundaries between objects and components.

Most unit tests aren't and their authors suffer for it. What is a unit test, really? How can writing them prevent classic testing problems? If you do write them, what trade-offs are you implicitly making?