tests(refactor): mail_lmtp_ip.bats (#3004)

* chore: Drop ENV `ENABLE_POSTFIX_VIRTUAL_TRANSPORT`

* tests(chore): Remove redundant `dovecot-lmtp` config

None of this is needed. Only relevant change is changing the LMTP service listener for Dovecot and that can be delegated to `user-patches.sh`.

* tests(refactor): Use `user-patches.sh` instead of replacing config file

The only relevant changes in `test/config/dovecot-lmtp` regarding LMTP was:
- `/etc/dovecot/dovecot.conf` (`protocols = imap lmtp`) and `/etc/dovecot/protocols.d/` (`protocols = $protocols lmtp`).
- `conf.d/10-master.conf` only changed the LMTP service listener from a unix socket to TCP on port 24 (_this was the only change required for the test to pass_).

None of those configs are required as:
- `protocols = imap pop3 lmtp` [is the upstream default](https://doc.dovecot.org/settings/core/#core_setting-protocols), no need to add `lmtp`.
- The LMTP service listener is now configured for the test with `user-patches.sh`.

* tests(refactor): `mail_lmtp_ip.bats`

- Converted to new testing conventions and common container helpers.
- `ENABLE_POSTFIX_VIRTUAL_TRANSPORT` was not relevant, dropped.
- Revised test cases, logic remains the same.
- Large custom config used was not documented and doesn't appear to serve any purpose. Simplified by replacing with a single modification with `user-patches.sh`.
- Added some additional comments for context of test and improvements that could be made.

* tests(chore): Adjust comments

The comment from `mail_hostname` provides no valid context, it was likely copied over from `tests.bats` in Oct 2020 by accident.

The email sent is just for testing, nothing relevant to LMTP.

---

Added additional comment for test to reference extra information from.

* tests(chore): Update similar log line matching

Extracts out the match pattern and formatting commands into separate vars (reduces horizontal scrolling), and includes extra docs about what the matched line should be expected to look like.

test/tests/serial/mail_hostname.bats

@@ -57,7 +57,6 @@ function setup_file() {
   wait_for_smtp_port_in_container mail_srs_domainname
   wait_for_smtp_port_in_container mail_domainname
 
-  # postfix virtual transport lmtp
   docker exec mail_override_hostname /bin/sh -c "nc 0.0.0.0 25 < /tmp/docker-mailserver-test/email-templates/existing-user1.txt"
   docker exec mail_non_subdomain_hostname /bin/sh -c "nc 0.0.0.0 25 < /tmp/docker-mailserver-test/email-templates/existing-user1.txt"
 }

test/tests/serial/mail_lmtp_ip.bats

@@ -1,44 +1,51 @@
-load "${REPOSITORY_ROOT}/test/test_helper/common"
+load "${REPOSITORY_ROOT}/test/helper/common"
+load "${REPOSITORY_ROOT}/test/helper/setup"
 
-setup_file() {
-  local PRIVATE_CONFIG PRIVATE_ETC
-  PRIVATE_CONFIG=$(duplicate_config_for_container .)
-  PRIVATE_ETC=$(duplicate_config_for_container dovecot-lmtp/ mail_lmtp_ip_dovecot-lmtp)
+# Originally contributed Jan 2017:
+# https://github.com/docker-mailserver/docker-mailserver/pull/461
+# Refactored with additional insights:
+# https://github.com/docker-mailserver/docker-mailserver/pull/3004
 
-  docker run -d --name mail_lmtp_ip \
-    -v "${PRIVATE_CONFIG}":/tmp/docker-mailserver \
-    -v "${PRIVATE_ETC}":/etc/dovecot \
-    -v "$(pwd)/test/test-files":/tmp/docker-mailserver-test:ro \
-    -e ENABLE_POSTFIX_VIRTUAL_TRANSPORT=1 \
-    -e POSTFIX_DAGENT=lmtp:127.0.0.1:24 \
-    -e PERMIT_DOCKER=container \
-    -h mail.my-domain.com -t "${NAME}"
+# NOTE: Purpose of feature is to use an ENV instead of providing a `postfix-main.cf`
+# to configure a URI for sending mail to an alternative LMTP server.
+# TODO: A more appropriate test if keeping this feature would be to run Dovecot via a
+# separate container to deliver mail to, and verify it was stored in the expected mail dir.
 
-  wait_for_finished_setup_in_container mail_lmtp_ip
+BATS_TEST_NAME_PREFIX='[ENV] (POSTFIX_DAGENT)'
+CONTAINER_NAME='dms-test_env_postfix-dagent'
+
+function setup_file() {
+  export LMTP_URI='lmtp:127.0.0.1:24'
+  init_with_defaults
+
+  local CONTAINER_ARGS_ENV_CUSTOM=(
+    --env PERMIT_DOCKER='container'
+    --env POSTFIX_DAGENT="${LMTP_URI}"
+  )
+
+  # Configure LMTP service listener in `/etc/dovecot/conf.d/10-master.conf` to instead listen on TCP port 24:
+  mv "${TEST_TMP_CONFIG}/dovecot-lmtp/user-patches.sh" "${TEST_TMP_CONFIG}/"
+
+  common_container_setup 'CONTAINER_ARGS_ENV_CUSTOM'
 }
 
-teardown_file() {
-  docker rm -f mail_lmtp_ip
-}
+function teardown_file() { _default_teardown ; }
 
-#
-# Postfix VIRTUAL_TRANSPORT
-#
-@test "checking postfix-lmtp: virtual_transport config is set" {
-  run docker exec mail_lmtp_ip /bin/sh -c "grep 'virtual_transport = lmtp:127.0.0.1:24' /etc/postfix/main.cf"
+@test "should have updated the value of 'main.cf:virtual_transport'" {
+  _run_in_container grep "virtual_transport = ${LMTP_URI}" /etc/postfix/main.cf
   assert_success
 }
 
-@test "checking postfix-lmtp: delivers mail to existing account" {
-  # maybe we can move this into the setup to speed things up further.
-  # this likely would need an async coroutine to avoid blocking the other tests while waiting for the server to come up
-  wait_for_smtp_port_in_container mail_lmtp_ip
-  run docker exec mail_lmtp_ip /bin/sh -c "nc 0.0.0.0 25 < /tmp/docker-mailserver-test/email-templates/existing-user1.txt"
+@test "delivers mail to existing account" {
+  wait_for_smtp_port_in_container "${CONTAINER_NAME}"
+
+  # Send a test mail:
+  _run_in_container bash -c "nc 0.0.0.0 25 < /tmp/docker-mailserver-test/email-templates/existing-user1.txt"
   assert_success
 
-  # polling needs to avoid wc -l's unconditionally successful return status
-  repeat_until_success_or_timeout 60 docker exec mail_lmtp_ip /bin/sh -c "grep 'postfix/lmtp' /var/log/mail/mail.log | grep 'status=sent' | grep ' Saved)'"
-  run docker exec mail_lmtp_ip /bin/sh -c "grep 'postfix/lmtp' /var/log/mail/mail.log | grep 'status=sent' | grep ' Saved)' | wc -l"
+  # Verify delivery was successful, log line should look similar to:
+  # postfix/lmtp[1274]: 0EA424ABE7D9: to=<user1@localhost.localdomain>, relay=127.0.0.1[127.0.0.1]:24, delay=0.13, delays=0.07/0.01/0.01/0.05, dsn=2.0.0, status=sent (250 2.0.0 <user1@localhost.localdomain> ixPpB+Zvv2P7BAAAUi6ngw Saved)
+  local MATCH_LOG_LINE='postfix/lmtp.* status=sent .* Saved)'
+  run timeout 60 docker exec "${CONTAINER_NAME}" bash -c "tail -F /var/log/mail/mail.log | grep --max-count 1 '${MATCH_LOG_LINE}'"
   assert_success
-  assert_output 1
 }