diff -r 000000000000 -r 6474c204b198 ipc/ipdl/test/README.txt
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ipc/ipdl/test/README.txt	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,10 @@
+There are two major categories of tests, segregated into different
+top-level directories under test/.
+
+The first category (ipdl/) is IPDL-compiler tests.  These tests check
+that the IPDL compiler is successfully compiling correct
+specifications, and successfully rejecting erroneous specifications.
+
+The second category (cxx/) is C++ tests of IPDL semantics.  These
+tests check that async/sync/rpc semantics are implemented correctly,
+ctors/dtors behave as they should, etc.