Language Testing: A Critical Perspective and Practical Guide by David Baker
This book provides a comprehensive overview of the issues and practices of modern language testing. It will enable the reader to make an informed choice of test instrument to satisfy the requirements of any given situation. It deals with the "why" as well as the "how" of language testing and it provides an even-handed treatment of different approaches to language testing rather than arguing the case for just one methodology. It also puts current practices into historical perspective and makes explicit the rationale and assumptions underlying them.