Independent Thoughts

For maximum effectiveness, builds should start with a clean slate by pulling all necessary code from the source code repository into an empty build sandbox, compiling the necessary components and building the application. Next, the application should be tested automatically to verify that it satisfies the quality criteria that the team manager and architect deem critical. At the very least, it should run all available test cases and report any failures that occur. By integrating testing into the build process, you can verify that no code has slipped through the tests that developers are required to perform before adding their code to the source code repository.

Often, groups shy away from integrating testing into the build during development and requiring that code pass designated tests in order for the build to be completed. They assume that as code is added and modified, errors inevitably are introduced into the application and that builds are going to fail frequently. These build failures are a blessing and not a problem, however: if there is a problem with the code, it is best to discover that problem as soon as it is introduced, when it is easiest, fastest and least costly to fix.

Moreover, if builds fail when errors are introduced, it introduces discipline into the group. If you implement policies stating that developers should add only clean, compiling code to the source control system and that the build will fail if any code does not pass the designated tests, it is easy for team members to identify anyone who is not adhering to this policy. If one developer introduces errors that cause a build to fail, the other team members can reprimand him the next morning. As a result, new developers quickly learn the value of adhering to the policy of adding only well-tested, compilable code to the source control system.

Build failures also lead all team members to value the quality of the code. Code is the group’s greatest asset, as it is the main thing that they have to show for all of their work. It also serves as a means of communication: developers exchange the majority of their ideas by reading and writing code. Thus, by protecting the quality of their code, developers can preserve their best ideas in the clearest, most concise way possible, as well as ensure that their communications are as effective as possible.