There are numerous methodologies available for developing and testing software. The methodology you choose depends on factors such as the nature of project, the project schedule, and resource availability. Although most software development projects involve periodic testing, some methodologies focus on getting the input from testing early in the cycle rather than waiting for input when a working model of the system is ready. Those methodologies that require early test involvement have several advantages, but also involve tradeoffs in terms of project management, schedule, customer interaction, budget, and communication among team members. This chapter discusses how testing fits into the various software development life cycles and then discusses the test-driven development practice in detail.

The Configuration Management Application Block (CMAB) is used to illustrate concepts in this chapter. The requirements for the CMAB are as follows:

It provides the functionality to read and store configuration information transparently in persistent storage media. The storage media are the Microsoft® SQL Server™ database system, the registry, and XML files.
It provides a configurable option to store the information in encrypted form and in plain text using XML notation.
It can be used with desktop applications and with Web applications that are deployed in a Web farm.
It caches configuration information in memory to reduce cross-process communication such as reading from any persistent medium. This caching reduces the response time of the request for configuration information. The expiration and scavenging mechanism for the data cached in memory is similar to the cron algorithm in UNIX.

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