Professional C__ - Marc Gregoire [442]
FIGURE 26-1
Once the bug has found its rightful owner, a fix is made and the developer marks the bug as “fixed.” At this point, the QA engineer verifies that the bug no longer exists and marks the bug as “closed” or reopens the bug if it is still present.
A less formal approach is shown in Figure 26-2. In this workflow, anybody can file a bug and assign an initial priority and a module. The module owner receives the bug report and can either accept it or reassign it to another engineer or module. When a correction is made, the bug is marked as “fixed.” Toward the end of the testing phase, all the implementation and QA engineers divide up the fixed bugs and verify that each bug is no longer present in the current build. The release is ready when all bugs are marked as “closed.”
FIGURE 26-2
Bug-Tracking Tools
There are many ways to keep track of software bugs, from informal e-mail- or spreadsheet-based schemes to expensive third-party bug-tracking software. The appropriate solution for your organization depends on the group’s size, the nature of the software, and the level of formality you wish to build around bug fixing.
There are also a number of free open-source bug-tracking solutions available. One of the more popular free tools for bug tracking is Bugzilla, written by the authors of the Mozilla web browser. As an open-source project, Bugzilla has gradually accumulated a number of useful features to the point where it now rivals expensive bug-tracking software packages. Among its many features are:
Customizable settings for a bug, including its priority, associated component, status, and so on
E-mail notification of new bug reports or changes to an existing report
Tracking of dependencies between bugs and resolution of duplicate bugs
Reporting and searching tools
A web-based interface for filing and updating bugs
Figure 26-3 shows a bug being entered into a Bugzilla project that was set up for this book. For our purposes, each chapter was input as a Bugzilla component. The filer of the bug can specify the severity of the bug (how big of a deal it is). A summary and description are included to make it possible to search for the bug or list it in a report format.
FIGURE 26-3
Bug-tracking tools like Bugzilla are becoming essential components of a professional software development environment. In addition to supplying a central list of currently open bugs, bug-tracking tools provide an important archive of previous bugs and their fixes. A support engineer, for instance, might use Bugzilla to search for a problem similar to one reported by a customer. If a fix was made, the support person will be able to tell the customer which version they need to update to or how to work around the problem.
UNIT TESTING
The only way to find bugs is through testing. One of the most important types of tests from a developer’s point of view is the unit test. Unit tests are pieces of code that exercise specific functionality of a class or subsystem. These are the finest-grained tests that you could possibly write. Ideally, one or more unit tests should exist for every low-level task that your code can perform. For example, imagine that you are writing a math library that can perform addition and multiplication. Your suite of unit tests might contain the following tests:
Basic test of addition
Test addition of large numbers
Test addition of negative numbers
Test addition of zero to a number
Test the commutative property of addition
Basic test of multiplication
Test multiplication of large numbers
Test multiplication of negative numbers
Test multiplication with zero
Test the commutative property of multiplication
Well-written unit tests protect you in many ways. First, they