caddy-frontend: Extend log listing test

So that this external interface keeps working, allowing automated log
extraction to keep working.

software/rapid-cdn/test/test.py

@@ -90,6 +90,27 @@ SOURCE_IPV6 = '::1'
 # IP on which test run, in order to mimic HTTP[s] access
 TEST_IP = os.environ['SLAPOS_TEST_IPV4']
 
+# "--resolve" inspired from https://stackoverflow.com/a/44378047/9256748
+DNS_CACHE = {}
+
+MONTH_DICT = {
+  'Jan': 1,
+  'Feb': 2,
+  'Mar': 3,
+  'Apr': 4,
+  'May': 5,
+  'Jun': 6,
+  'Jul': 7,
+  'Aug': 8,
+  'Sep': 9,
+  'Oct': 10,
+  'Nov': 11,
+  'Dec': 12,
+}
+match_nginx_datetime = re.compile(
+  '(?P<dow>...), (?P<day>..) (?P<monthname>...) (?P<year>....) '
+  '(?P<hour>..):(?P<minute>..):(?P<second>..)',
+).match
 
 def unicode_escape(s):
   return s.encode('unicode_escape').decode()
@@ -1051,9 +1072,45 @@ class HttpFrontendTestCase(SlapOSInstanceTestCase):
       'application/json',
       result.headers['Content-Type']
     )
-    self.assertEqual(
-      sorted([q['name'] for q in result.json()]),
+    result_json = result.json()
+    # expected content for each file entry:
+    # - 'type' with files having the value 'file'
+    # - 'name' with the file's basename as value
+    # - 'mtime' with the modification time (though this specific part
+    #   probably cannot be reliably tested) in some specific format (which
+    #   happens to be the one nginx produces)
+    # - 'size' with the file's size (again, not much to actually test for
+    #   exctitude I guess)
+    self.assertEqual(
+      sorted([q['name'] for q in result_json]),
       ['access.log', 'backend.log', 'frontend.log'])
+    self.assertIn(
+      'file',
+      {q['type'] for q in result_json},
+    )
+    # The following loop must not raise to pass the test, but nothing specific
+    # is done with extracted values.
+    for entry in result_json:
+      self.assertIn('size', entry)
+      parsed_remote_mtime = match_nginx_datetime(
+        entry['mtime'],
+      ).groupdict()
+      datetime.datetime(
+        int(parsed_remote_mtime['year'], 10),
+        MONTH_DICT[parsed_remote_mtime['monthname']],
+        int(parsed_remote_mtime['day'], 10),
+        int(parsed_remote_mtime['hour'], 10),
+        int(parsed_remote_mtime['minute'], 10),
+        int(parsed_remote_mtime['second'], 10),
+      )
+    self.assertEqual(
+      http.client.OK,
+      requests.get(url + 'access.log', verify=False).status_code
+    )
+    self.assertEqual(
+      http.client.OK,
+      requests.get(url + 'error.log', verify=False).status_code
+    )
     # assert only for few tests, as logs are available for sure only
     # for few of them
     for test_name in [