Abuild defines three built-in targets for running test suites: check, test, and test-only. The check and test targets are synonyms. Both targets first ensure that a build item is built (by depending on the all target) and then run the build item's test suites, if any. The test-only target also runs a build item's test suite, but it does not depend on all. This means that it will almost certainly fail when run on a clean build tree. The test-only target is useful for times when you know that a build item is already built and you want to run the test suite on what is there now. One case in which you might want to do this would be if you had just started editing some source files and decided you wanted to rerun the test suite on the existing executables before rebuilding them. Another case in which this could be useful is if you had just built a build tree and then wanted to immediately go back and run all the test suites without having to pay the time penalty of checking to make sure each build is up to date. In this case, you could run abuild --build=all test-only immediately after the build was completed. Such a usage style might be appropriate for autobuilders or other systems that build and test a build tree in a controlled environment.