第9章ソフトウェア工学

A quite common tool used in software development is a version control system, which stores the history of changes to source code and facilitates collaboration of multiple developers. The most popular version control system today is Git, which is often used with a common hub, such as GitHub or Bitbucket.

Git stores the project source code written by a developer in a repository that is typically on the developer’s machine. Developers can push their code to a project repository for integration purposes. The main features of Git are as follows:

• It tracks changes in your source code.

• It enables reverting the changes.

• It facilitates collaborative development.

GitHub facilitates code sharing among developers by allowing developers to modify source code on their own machine, commit changes to a Git repository on their machine, and then push changes from their machine to GitHub so that other developers can access them.

Many open-source projects are hosted on GitHub that allow people to download their source code and contribute. Figure 9.23 shows a standard GitHub page, in this case from the JavaScript library called the jQuery project.

Another common software development tool is a bug tracking system, which aids in the tracking and resolution of fixing issues with software. Bug tracking software stores information about issues that have been reported and their resolution.

A common workflow with the bug tracking system is as follows: when a customer or a tester reports a bug, a new record in the bug tracking system is created. Then, the project manager or any other team member assigns the bug to a developer. The bug report must provide instructions as to how the bug manifests and may be fixed so that the assigned developer can reproduce it and decide how to proceed. Here’s a general breakdown of how bug tracking works:

• If the bug cannot be reproduced or if it is not a bug but a request for a new feature, it will be rejected.

• If the report describes a bug that was already reported, it will be marked as a duplicate.

• If the fix is scheduled for a next release, it will be marked as deferred.

When the developer fixes the bug, the code should be retested to confirm that the bug has truly been resolved. Figure 9.24 illustrates a common bug reporting and tracking flow.

Figure 9.25 shows a bug tracking tool—the jQuery bug tracking tool—that is available on GitHub.

In January of 2022, the San Francisco Unified School District rolled out a new employee information system, which included the payroll for over 10,000 employees. Unfortunately, the development team did not do a thorough job of testing this system, and it contained a number of bugs when it was launched. As a result, hundreds of teachers and staff members did not, even after several months, receive paychecks from the system.

Because the system was unable to process payroll, hundreds of employees were unable to pay their rent, medical bills, and other expenses. In this case, the delivery of a flawed system harmed people.

This is an example where a system’s product did not adhere to the highest standards and failed to be tested to a level that would avoid an issue that directly harmed many of the employees who relied on the system. While the Chief Technology Officer issued apologies and assigned 100% of the project staff to get the issues resolved, the reality is—and ethically speaking—more time should have been allotted to test the system prior to it replacing the old system.

We typically think about all of the ways that technology and systems can help people. It is also important to acknowledge there are risks also. Bugs in software can have a significant impact on the people affected. This reinforces the importance of testing and validating a system before we release it.