help: tests: Fix functional test to check for status logs

Fixes: #2171.

Since systemd version 250, journalctl does not print the header line '-- Journal
begins... --'. To accommodate those changes, read the status log lines
accurately and check that they are not empty.

Tests:

- Run help functional tests on stable, testing and unstable.

- Modify code to not print status logs and notice that the functional test
fails.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/help/templates/statuslog.html

@@ -28,7 +28,7 @@
   </p>
 
   <p>
-    <pre>{{ data }}</pre>
+    <pre class="status-log">{{ data }}</pre>
   </p>
 
 {% endblock %}

plinth/modules/help/tests/test_functional.py

@@ -4,6 +4,7 @@ Functional, browser based tests for help app.
 """
 
 import pytest
+
 from plinth.tests import functional
 
 pytestmark = [pytest.mark.system, pytest.mark.essential, pytest.mark.help]
@@ -32,5 +33,6 @@ def _go_to_status_logs(browser):
 
 
 def _are_status_logs_shown(browser):
-    return (browser.is_text_present('Logs begin')
-            or browser.is_text_present('Journal begins'))
+    status_log = browser.find_by_css('.status-log').first.text
+    return ('-- No entries --' in status_log
+            or status_log.strip().splitlines())