tests: avoid side effects of $SHELL environment variable

Since non interactive shells don't generally set $SHELL,
its value is propagated through the tests and may cause issues;
for example if $SHELL implicitly adjusts $PATH when run.
Instead we set $SHELL to that determined by the posix-shell module,
and use that consistently for all test sub scripts,
including those created thorugh the `split --filter` command.

* tests/local.mk: Explicitly set $SHELL to $(PREFERABLY_POSIX_SHELL)
which defaults to $CONFIG_SHELL and thus usually /bin/sh.
* tests/envvar-check: Remove bash environment variables with
side effects, in case /bin/bash was selected for $SHELL.
* tests/misc/help-version.sh: Remove redundant initialization of $SHELL.
* tests/install/strip-program.sh: Use $SHELL for sub script.
* tests/misc/sort-compress-hang.sh: Likewise.
* tests/misc/sort-compress-proc.sh: Likewise.
* tests/misc/sort-compress.sh: Likewise.
* tests/misc/timeout-group.sh: Likewise.
* tests/rm/fail-eperm.xpl: Remove redundant elision of bash env vars.
* tests/misc/pwd-long.sh: Likewise.

6 files changed, 11 insertions, 17 deletions

diff --git a/tests/misc/help-version.sh b/tests/misc/help-version.sh
index e0dd721f9..78150374d 100755
--- a/tests/misc/help-version.sh
+++ b/tests/misc/help-version.sh
@@ -17,12 +17,6 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-# Ensure that $SHELL is set to *some* value and exported.
-# This is required for dircolors, which would fail e.g., when
-# invoked via debuild (which removes SHELL from the environment).
-test "x$SHELL" = x && SHELL=/bin/sh
-export SHELL
-
 . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
 
 # Terminate any background processes
diff --git a/tests/misc/pwd-long.sh b/tests/misc/pwd-long.sh
index 927fdcff2..3ced777ae 100755
--- a/tests/misc/pwd-long.sh
+++ b/tests/misc/pwd-long.sh
@@ -56,7 +56,6 @@ sub normalize_to_cwd_relative ($$$)
 }
 
 # Set up a safe, well-known environment
-delete @ENV{qw(BASH_ENV CDPATH ENV)};
 $ENV{IFS}  = '';
 
 # Taint checking requires a sanitized $PATH.  This script performs no $PATH
diff --git a/tests/misc/sort-compress-hang.sh b/tests/misc/sort-compress-hang.sh
index 9cfd6cc90..dc101fea8 100755
--- a/tests/misc/sort-compress-hang.sh
+++ b/tests/misc/sort-compress-hang.sh
@@ -20,8 +20,8 @@
 print_ver_ sort
 very_expensive_
 
-cat <<\EOF >compress || framework_failure_
-#!/bin/sh
+cat <<EOF >compress || framework_failure_
+#!$SHELL
 tr 41 14 || exit
 touch ok
 EOF
diff --git a/tests/misc/sort-compress-proc.sh b/tests/misc/sort-compress-proc.sh
index 4ad42d514..05017a54f 100755
--- a/tests/misc/sort-compress-proc.sh
+++ b/tests/misc/sort-compress-proc.sh
@@ -32,8 +32,9 @@ insize=$(stat -c %s - <in) || fail=1
 # This compressor's behavior is adjustable via environment variables.
 export PRE_COMPRESS=
 export POST_COMPRESS=
-cat <<\EOF >compress || framework_failure_
-#!/bin/sh
+
+printf '%s\n' '#!'"$SHELL" >compress || framework_failure_
+cat <<\EOF >>compress || framework_failure_
 eval "$PRE_COMPRESS"
 tr 41 14 || exit
 eval "$POST_COMPRESS"
diff --git a/tests/misc/sort-compress.sh b/tests/misc/sort-compress.sh
index 605d539ba..584110e12 100755
--- a/tests/misc/sort-compress.sh
+++ b/tests/misc/sort-compress.sh
@@ -27,8 +27,8 @@ sort -S 1k in > out || fail=1
 compare exp out || fail=1
 
 # Create our own gzip program that will be used as the default
-cat <<\EOF > gzip || fail=1
-#!/bin/sh
+cat <<EOF > gzip || fail=1
+#!$SHELL
 tr 41 14
 touch ok
 EOF
diff --git a/tests/misc/timeout-group.sh b/tests/misc/timeout-group.sh
index 054c5aec6..d47f0dc83 100755
--- a/tests/misc/timeout-group.sh
+++ b/tests/misc/timeout-group.sh
@@ -30,8 +30,8 @@ print_ver_ timeout
 
 setsid true || skip_ "setsid required to control groups"
 
-cat > timeout.cmd <<\EOF
-#!/bin/sh
+printf '%s\n' '#!'"$SHELL" > timeout.cmd || framework_failure_
+cat >> timeout.cmd <<\EOF
 trap 'touch int.received; exit' INT
 touch timeout.running
 count=$1
@@ -42,8 +42,8 @@ done
 EOF
 chmod a+x timeout.cmd
 
-cat > group.sh <<\EOF
-#!/bin/sh
+cat > group.sh <<EOF
+#!$SHELL
 trap '' INT
 timeout --foreground 25 ./timeout.cmd 20&
 wait