Ourproject has about 100 application source files and 50 test files. When I repeatedly run the tests (with no changes) on my local machine they take about 3-1/2 minutes. About half of that time is spent determining what files to compile and what include directories to use and the other half of that time is spent doing the compiling (one file at a time).

When (re)building a large project programmers typically use a tool likemake to keep track of dependencies and avoid recompiling files that have not changed. Of course, there is a cost to maintaining theMakefile but it is typically worth it.

With this change we allow the user to provide aMakefile that considerably shortens the process (my project takes 10 seconds to rerun all tests if there are no changes; 15 seconds if there is a change to one test file; and 25 seconds if there is a change to an application file).

If the user does not provide aMakefile then the prior behavior is preserved. Note that this is disabled on Windows (I don't know enough about the build environment; does it supportg++?).