test: use dtach(1) instead of screen(1) in emacs tests

dtach is simpler than screen and is not setuid/setgid program so
TMPDIR does not get cleared by dynamic loader when executed

diff --git a/test/test-lib.sh b/test/test-lib.sh
index c81c709b511ffbbbee1205379a4dd6ce8ee67e2a..d88548b3838868146269dbdc2dcf1992ab04a22d 100755 (executable)
--- a/test/test-lib.sh
+++ b/test/test-lib.sh
@@ -39,7 +39,7 @@ done,*)
        ;;
 esac
 
-# Keep the original TERM for say_color
+# Keep the original TERM for say_color and test_emacs
 ORIGINAL_TERM=$TERM
 
 # For repeatability, reset the environment to known value.
@@ -50,8 +50,6 @@ TZ=UTC
 TERM=dumb
 export LANG LC_ALL PAGER TERM TZ
 GIT_TEST_CMP=${GIT_TEST_CMP:-diff -u}
-export SCREENRC=/dev/null
-export SYSSCREENRC=/dev/null
 
 # Protect ourselves from common misconfiguration to export
 # CDPATH into the environment
@@ -843,12 +841,15 @@ EOF
 test_emacs () {
        if [ -z "$EMACS_SERVER" ]; then
                EMACS_SERVER="notmuch-test-suite-$$"
-               # start a detached screen session with an emacs server
-               screen -S "$EMACS_SERVER" -d -m "$TMP_DIRECTORY/run_emacs" \
-                       --no-window-system \
-                       --eval "(setq server-name \"$EMACS_SERVER\")" \
-                       --eval '(server-start)' \
-                       --eval "(orphan-watchdog $$)" || return
+               # start a detached session with an emacs server
+               # user's TERM is given to dtach which assumes a minimally
+               # VT100-compatible terminal -- and emacs inherits that
+               TERM=$ORIGINAL_TERM dtach -n "$TMP_DIRECTORY/emacs-dtach-socket.$$" \
+                       sh -c "stty rows 24 cols 80; exec '$TMP_DIRECTORY/run_emacs' \
+                               --no-window-system \
+                               --eval '(setq server-name \"$EMACS_SERVER\")' \
+                               --eval '(server-start)' \
+                               --eval '(orphan-watchdog $$)'" || return
                # wait until the emacs server is up
                until test_emacs '()' 2>/dev/null; do
                        sleep 1