If there are problems, stopping during the build process permits them to see exactly what is going wrong, and where. After the binary package has been created. This is handy when the application is not yet ready for packaging and needs some fine tuning. This way, once the package builds, installs, and operates properly, the required patches to the original sources can be created, and plugged into the package's spec file. Testing Newly Built Packages Of course, the fact that an application has been packaged successfully doesn't necessarily mean that it will operate correctly when the package is actually installed.
Testing is required.
In the case of our example, it's perfect and doesn't need such testing. That way, it'll just blow away the files installed by the build process and replace them with the packaged files. For another thing, the sheer number of files makes it likely that you'll miss one or two. They aren't overwritten by RPM since they weren't in the package. If you go to test the application then, it will find every file it needs.