--- /dev/null
+This directory contains tests for various Vim features.
+
+If it makes sense, try to add a new test to an already existing file. You may
+want to separate it from other tests in that file using :" (that's an Ex
+command comment).
+
+The numbered tests are older, we have switched to named tests.
+
+To add a new test:
+1) Create test_<subject>.in and test_<subject>.ok files.
+2) Add them to all Makefiles (Make*) in alphabetical order (search for an
+ existing test_file.out to see where to add the new one).
+3) Use make test_<subject>.out to run a single test file in src/testdir/.
+4) Also add an entry in src/Makefile.
+
+Keep in mind that the files are used as if everything was typed.
+A line break is like pressing Enter. If that happens on the last line you'll
+hear a beep.