You can fool some of the people all of the time and
all of the people some of the time, but you cannot
fool all of the people all of the time.
Abraham Lincoln
So far, we have developed and written tests for self-contained code, which is code without dependencies. These are,
and have always been, the easier parts of any system
development, the easily sharable parts, and the reusable
parts. A more formidable challenge for TDD is testing
code in the middle, which consists of the modules that must work through
other modules, functions, and data stores to get their
job done. This part of the book is dedicated to
demonstrating techniques to effectively test the code in
the middle.
