updated for version 7.4.420

Problem:    It's not obvious how to add a new test.
Solution:   Add a README file. (Christian Brabandt)

src/testdir/README.txt

@@ -0,0 +1,18 @@
+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.

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    420,
 /**/
     419,
 /**/