How we did it:
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Michael C. Feathers
The average book on Agile software development describes a fairyland of greenfield projects, with wall-to-wall tests that run after every few edits, and clean & simple source code.
The average software project, in our industry, was written under some aspect of code-and-fix, and without automated unit tests. And we can't just throw this code away; it represents a significant effort debugging and maintaining. It contains many latent requirements decisions. Just as Agile processes are incremental, Agile adoption must be incremental too. No more throwing away code just because it looked at us funny.
Mike begins his book with a very diplomatic definition of "Legacy". I'l skip ahead to the undiplomatic version: Legacy code is code without unit tests.
Before cleaning that code up, and before adding new features and removing bugs, such code must be de-legacified. It needs unit tests.
To add unit tests, you must change the code. To change the code, you need unit tests to show how safe your change was.
The core of the book is a cookbook of recipes to conduct various careful attacks. Each presents a particular problem, and a relatively safe way to migrate the code towards tests.
Code undergoing this migration will begin to experience the benefits of unit tests, and these benefits will incrementally make new tests easier to write. These efforts will make aspects of a legacy codebase easy to change.
It's an unfortunate commentary on the state of our programming industry how much we need this book.
A. K. Dewdney
No other volume provides as broad, as thorough, or as accessible an introduction to the realm of computers as A. K. Dewdney's The Turing Omnibus. Updated and expanded, The Turing Omnibus offers 66 concise, brilliantly written articles on the major points of interest in computer science theory, technology, and applications. New for this tour: updated information on algorithms, detecting primes, noncomputable functions, and self-replicating computers--plus completely new sections on the Mandelbrot set, genetic algorithms, the Newton-Raphson Method, neural networks that learn, DOS systems for personal computers, and computer viruses.