If the variable @code{TESTS} is defined, its value is taken to be a list
of programs to run in order to do the testing. The programs can either
be derived objects or source objects; the generated rule will look both
-in @var{srcdir} and @file{.}.
+in @var{srcdir} and @file{.}. Programs needing data files should look
+for them in @var{srcdir} (which is both an environment variable and a
+make variable) so they work when building in a separate directory
+(@pxref{Build Directories,,,autoconf}), and in particular for the
+@code{distcheck} target (@pxref{Dist}).
The number of failures will be printed at the end of the run. If a
given test program exits with a status of 77, then its result is ignored