Summary

The performance or quality of the test effort is normally judged by the number of errors that occur after testing has been concluded-that is, after the product has been shipped to the users. The stringency of the definition of what is "adequate" varies with the criticality of the system under consideration. Generally, it can be said that an adequate test effort is one where few serious bugs occur in the product after it has been distributed to the user community. An adequate test effort requires adequate test coverage and adequate bug removal.

To determine the quality or adequacy of the test effort, we need to measure certain fundamental things to answer questions like "How big is it?" meaning the test effort, "How long will it take?", and "How much will be tested?" A test inventory is an excellent tool for answering these questions.

Determining the requirements for an adequate test effort requires that many factors be itemized, estimated, and totaled. The test inventory is an excellent tool for this job. The test inventory should be constructed using a combination of analytical and nonanalytical techniques to ensure the best overall coverage. Like the public grocery list posted on the refrigerator door, it will benefit from having the broadest possible input. When it is mature, the test inventory should contain a reference to every test that has been devised for the system. If a thorough analysis of the system is conducted, the number of tests on the inventory will far exceed the time and resources available to run them during the test effort. MITs risk analysis is used on the inventory to identify the most important tests and the optimal test coverage for the effort. The rest of this book gives you the theoretical and practical steps to develop a mature test inventory that will help you in each phase of your test effort.

In this chapter, I gave you the big picture of what the inventory is and what it can do for you and the quality of your test effort. The rest of this book deals with how to develop a test inventory that suits your needs, prioritize its items, negotiate for the resources you need to succeed, and finally, select and design tests. The first step is to construct a preliminary inventory. I will show you how I do this in the next chapter, "How to Build a Test Inventory."