scripts: added TZ environment variable to set timezone (#2530)

test/mail_time.bats

@@ -0,0 +1,29 @@
+load 'test_helper/common'
+
+setup_file() {
+  local PRIVATE_CONFIG
+  PRIVATE_CONFIG="$(duplicate_config_for_container .)"
+
+  docker run -d --name mail_time \
+    -v "${PRIVATE_CONFIG}":/tmp/docker-mailserver \
+    -v "$(pwd)/test/test-files":/tmp/docker-mailserver-test:ro \
+    -e TZ='Asia/Jakarta' \
+    -e LOG_LEVEL=debug \
+    -h mail.my-domain.com -t "${NAME}"
+
+  wait_for_smtp_port_in_container mail_time
+}
+
+teardown_file() {
+    docker rm -f mail_time
+}
+
+@test "checking time: setting the time with TZ works correctly" {
+  run docker exec mail_time cat /etc/timezone
+  assert_success
+  assert_output 'Asia/Jakarta'
+
+  run docker exec mail_time date '+%Z'
+  assert_success
+  assert_output 'WIB'
+}