[PATCH V3 1/1] test/test-lib.sh: use vt100 as dtach terminal if TERM dumb or unset/empty

[Tomi Ollila <tomi.ollila@iki.fi>]

The TERM environment variable is set to 'dumb' when running tests, but
the original value of it is stored for echoing colors and running emacs
(somewhat interactively) in detached session. Emacs requires some
terminal control sequences to be available for interactive operation.
In case original TERM is (also) 'dumb' (or unset/empty) emacs cannot
run interactively. To fix this problem dtach (and emacs as it's child
process) is run with TERM=vt100 in case original TERM was unset, empty
or 'dumb'. This way there is a chance to run emacs tests with different
user terminals and potentially find problems there.
---

Obsoletes id:1359011360-15591-1-git-send-email-tomi.ollila@iki.fi

To be accurate (instead of potentially confusing), the commit
message and comments have been edited to mention 'unset or empty'
instead of 'nonexistent'. No functional changes (to neither v1 or v2
of this patch).

 test/test-lib.sh | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/test/test-lib.sh b/test/test-lib.sh
index 6ce3b31..1567178 100644
--- a/test/test-lib.sh
+++ b/test/test-lib.sh
@@ -41,6 +41,10 @@ esac
 # Keep the original TERM for say_color and test_emacs
 ORIGINAL_TERM=$TERM
 
+# dtach(1) provides more capable terminal environment to anything
+# that requires more than dumb terminal...
+[ x"${TERM:-dumb}" = xdumb ] && DTACH_TERM=vt100 || DTACH_TERM=$TERM
+
 # For repeatability, reset the environment to known value.
 LANG=C
 LC_ALL=C
@@ -996,9 +1000,10 @@ test_emacs () {
 		fi
 		server_name="notmuch-test-suite-$$"
 		# start a detached session with an emacs server
-		# user's TERM is given to dtach which assumes a minimally
+		# user's TERM (or 'vt100' in case user's TERM is unset, empty
+		# or 'dumb') is given to dtach which assumes a minimally
 		# VT100-compatible terminal -- and emacs inherits that
-		TERM=$ORIGINAL_TERM dtach -n "$TEST_TMPDIR/emacs-dtach-socket.$$" \
+		TERM=$DTACH_TERM dtach -n "$TEST_TMPDIR/emacs-dtach-socket.$$" \
 			sh -c "stty rows 24 cols 80; exec '$TMP_DIRECTORY/run_emacs' \
 				--no-window-system \
 				$load_emacs_tests \
-- 
1.8.0