test: Add testenv_enter.sh to ease debugging testenv

The script testenv_enter.sh, by default, runs /bin/sh in the environment
currently setup.

A bit easier than copy pasting the old hint text printed before test run.

Signed-off-by: Magnus Malm <magnusmalm@gmail.com>

test/lib.sh

@@ -83,6 +83,7 @@ teardown() {
     texec kill -SIGUSR2 1
 
     wait
+    rm "$TEST_DIR"/running_test.pid
 }
 
 trap teardown EXIT
@@ -98,6 +99,7 @@ log "$color_reset" '--' ''
 # Setup
 "$TEST_DIR/testenv_start.sh" finit &
 finit_ppid=$!
+echo "$finit_ppid" > "$TEST_DIR"/running_test.pid
 finit_pid=$(retry "pgrep -P $finit_ppid")
 
 tty=/dev/$(texec cat /sys/class/tty/console/active)

test/testenv_enter.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+set -eu
+
+cmd=""
+if [ "$#" -lt 1 ]; then
+    cmd="/bin/sh"
+else
+    cmd=$1
+    shift
+fi
+
+PID_FILE=$(dirname "$0")/running_test.pid
+
+if [ -f  "$PID_FILE" ] ; then
+    target=$(cat "$PID_FILE")
+    target=$(pgrep -P "$target")
+else
+    echo "No test running!"
+    exit 1
+fi
+
+"$(dirname "$0")"/testenv_exec.sh "$target" "$cmd" "$@"

test/testenv_start.sh

@@ -5,7 +5,7 @@ set -eu
 TEST_DIR=$(dirname "$0")
 TESTS_ROOT="$(pwd)/${TEST_DIR}/test_root"
 
->&2 echo "Hint: Execute '${TEST_DIR}/testenv_exec.sh \$(pgrep -P $$) /bin/sh; reset' to enter the test namespace"
+>&2 echo "Hint: Execute 'test/testenv_enter.sh' to enter the test namespace"
 
 unshare=$(command -v unshare)
 chroot=$(command -v chroot)