3 files changed, 19 insertions, 6 deletions

diff --git a/src/mailman/rules/dmarc.py b/src/mailman/rules/dmarc.py
index 122aefe7b..8180211bc 100644
--- a/src/mailman/rules/dmarc.py
+++ b/src/mailman/rules/dmarc.py
@@ -102,12 +102,13 @@ def ensure_current_suffix_list():
     return cached_copy_path
 
 
-def parse_suffix_list():
+def parse_suffix_list(filename=None):
     # Parse the suffix list into a per process cache.
-    cached_copy_path = ensure_current_suffix_list()
+    if filename is None:
+        filename = ensure_current_suffix_list()
     # At this point the cached copy must exist and is as valid as possible.
     # Read and return the contents as a UTF-8 string.
-    with open(cached_copy_path, 'r', encoding='utf-8') as fp:
+    with open(filename, 'r', encoding='utf-8') as fp:
         for line in fp:
             if not line.strip() or line.startswith('//'):
                 continue
@@ -121,8 +122,8 @@ def parse_suffix_list():
             else:
                 exception = False
             parts.reverse()
-            k = DOT.join(parts)
-            suffix_cache[k] = exception
+            key = DOT.join(parts)
+            suffix_cache[key] = exception
 
 
 def _get_dom(d, l):
diff --git a/src/mailman/rules/tests/data/org_domain.txt b/src/mailman/rules/tests/data/org_domain.txt
index 4e6f7816e..e10db8a32 100644
--- a/src/mailman/rules/tests/data/org_domain.txt
+++ b/src/mailman/rules/tests/data/org_domain.txt
@@ -17,7 +17,7 @@ org
 !city.kobe.jp
 
 // A line with a trailing comment for testing
-co.uk  some nonesence
+co.uk  some nonsense
 
 // A line with leading white space (ignored)
   example.biz
diff --git a/src/mailman/rules/tests/test_dmarc.py b/src/mailman/rules/tests/test_dmarc.py
index df5127895..7748343eb 100644
--- a/src/mailman/rules/tests/test_dmarc.py
+++ b/src/mailman/rules/tests/test_dmarc.py
@@ -173,6 +173,18 @@ To: ant@example.com
             'anne@example.info (_dmarc.example.info). '
             'Abstract base class shared by all dnspython exceptions.\n')
 
+    def test_parser(self):
+        data_file = resource_filename(
+            'mailman.rules.tests.data', 'org_domain.txt')
+        dmarc.parse_suffix_list(data_file)
+        # There is no entry for example.biz because that line starts with
+        # whitespace.
+        self.assertNotIn('biz.example', self.cache)
+        # The file had !city.kobe.jp so the flag says there's an exception.
+        self.assertTrue(self.cache['jp.kobe.city'])
+        # The file had *.kobe.jp so there's no exception.
+        self.assertFalse(self.cache['jp.kobe.*'])
+
 
 # New in Python 3.5.
 try: