Developing DTrace on FreeBSD
While the Illumos project continues to work on DTrace there is much to be done to enhance this code on FreeBSD. This page includes information about how to develop DTrace code on FreeBSD natively, including how to add new providers as well as proper testing procedures.
Where Your Files Should Reside
Testing Your Changes
DTrace comes with an extensive test suite that has been integrated into the FreeBSD source tree. All of the tests reside in: src/cddl/contrib/opensolaris/cmd/dtrace/test/tst/
The perl script that runs the tests resides in: src/cddl/contrib/opensolaris/cmd/dtrace/test/cmd/scripts/dtest.pl
To run the test suite you can execute a single file:
sudo ./dtest.pl ../../tst/common/enum/tst.EnumValAssign.d /usr/sbin/dtrace testing ../../tst/common/enum/tst.EnumValAssign.d ... 
Each test runs in it's own process and the number in brackets is the process ID.
If a test fails a directory is created named failed.#### and the test suite tells you the test that failed and where to find the failure. For example, if you forget to run the test with root privileges that's a silly user error, but here is what you'll see:
./dtest.pl ../../tst/common/enum/tst.EnumValAssign.d /usr/sbin/dtrace testing ../../tst/common/enum/tst.EnumValAssign.d ...  ERROR: tst.EnumValAssign.d returned 1 instead of 0; details in failure.6
and in the failure.6 directory you will find several files: 19604.err 19604.out README and tst.EnumValAssign.d
The last file in the list is just a copy of the D script that was executed and failed.
The README shows the error line generated by the test script itself:
ERROR: ../../tst/common/enum/tst.EnumValAssign.d returned 1 instead of 0
which doesn't tell us what really went wrong, that, in this case, is in the .err file:
dtrace: failed to initialize dtrace: DTrace requires additional privileges
Since the test generated no real output, other than error output, the .out file is empty.