2. Background

Writing defect-free software is a difficult proposition. There are many dimensions to the problem and there is much confusion regarding what is meant by different terms in different contexts. We have found it worthwhile to spend a little time reviewing the subject and defining some terms.

Software testing may be loosely defined as the process of executing a program with the intent of finding errors. When one enters a discussion regarding software testing, it quickly becomes apparent that there are many distinct mind-sets with which one can approach the subject.

For example, one could break the process into broad functional categories like “correctness testing,” “performance testing,” “robustness testing” and “security testing.” Another way to look at the problem is by life-cycle: “requirements testing,” “design testing,” “acceptance testing,” and “maintenance testing.” Yet another view is by the scope of the tested system. In this case one may speak of “unit testing,” “component testing,” “integration testing,” and “system testing.” These terms are also not standardized in any way, and so “maintenance testing” and “regression testing” may be heard interchangeably. Additionally, these terms are often misused.

There are also a number of different philosophical approaches to software testing. For example, some organizations advocate writing test programs before actually implementing the desired software, yielding “test-driven development.” Some organizations advocate testing from a customer perspective as soon as possible, following a parallel with the agile development process: “test early and test often.” This is sometimes called “agile testing.” It seems that there is at least one approach to testing for every development methodology.

The ns-3 project is not in the business of advocating for any one of these processes, but the project as a whole has requirements that help inform the test process.

Like all major software products, ns-3 has a number of qualities that must be present for the product to succeed. From a testing perspective, some of these qualities that must be addressed are that ns-3 must be “correct,” “robust,” “performant” and “maintainable.” Ideally there should be metrics for each of these dimensions that are checked by the tests to identify when the product fails to meet its expectations / requirements.

This document was generated on August 20, 2010 using texi2html 1.82.