test: New test: test_start_stop_service

Add a new test that verifies that Finit will:
- Start a service that's been added to the config
- Stop the service once it's removed from the config

The second step is currently failing.

Signed-off-by: Jacques de Laval <jacques@de-laval.se>

test/testenv_start.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+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"
+
+# Not supported by Busybox unshare:
+#  --cgroup --time
+export PATH=/sbin:/bin
+exec unshare \
+    --user --map-root-user \
+    --fork --pid --mount-proc \
+    --mount \
+    --mount-proc \
+    --uts --ipc --net \
+    chroot "$TESTS_ROOT" /bin/chrootsetup.sh "$@"