To add a new IPDL C++ unit test, you need to create (at least) the following files (for a test "TestFoo"): - PTestFoo.ipdl, specifying the top-level protocol used for the test - TestFoo.h, declaring the top-level parent/child actors used for the test - TestFoo.cpp, defining the top-level actors - (make sure all are in the namespace mozilla::_ipdltest) Next - add PTestFoo.ipdl to ipdl.mk - append TestFoo to the variable IPDLTESTS in Makefile.in The IPDL test harness will try to execute |testFooParentActor->Main()| to kick off your test. Make sure you define |TestFooParent::Main()|. If your test passes its criteria, please call |MOZ_IPDL_TESTPASS("msg")| and "exit gracefully". If your tests fails, please call |MOZ_IPDL_TESTFAIL("msg")| and "exit ungracefully", preferably by abort()ing. If all goes well, running make -C $OBJDIR/ipc/ipdl/test/cxx will update the file IPDLUnitTests.cpp (the test launcher), and your new code will be built automatically. You can launch your new test by invoking make -C $OBJDIR/ipc/ipdl/test/cxx check If you want to launch only your test, run cd $OBJDIR/dist/bin ./run-mozilla.sh ./ipdlunittest TestFoo For a bare-bones example of adding a test, take a look at PTestSanity.ipdl, TestSanity.h, TestSanity.cpp, and how "TestSanity" is included in ipdl.mk and Makefile.in.