Issue #29392: Prevent crash when passing invalid arguments into msvcrt module.

1 files changed, 20 insertions, 0 deletions

diff --git a/Lib/test/test_email/test_message.py b/Lib/test/test_email/test_message.py
index 434516226c..f3a57df9e9 100644
--- a/Lib/test/test_email/test_message.py
+++ b/Lib/test/test_email/test_message.py
@@ -764,6 +764,26 @@ class TestEmailMessage(TestEmailMessageBase, TestEmailBase):
         m.set_content(content_manager=cm)
         self.assertEqual(m['MIME-Version'], '1.0')
 
+    def test_as_string_uses_max_header_length_by_default(self):
+        m = self._str_msg('Subject: long line' + ' ab'*50 + '\n\n')
+        self.assertEqual(len(m.as_string().strip().splitlines()), 3)
+
+    def test_as_string_allows_maxheaderlen(self):
+        m = self._str_msg('Subject: long line' + ' ab'*50 + '\n\n')
+        self.assertEqual(len(m.as_string(maxheaderlen=0).strip().splitlines()),
+                         1)
+        self.assertEqual(len(m.as_string(maxheaderlen=34).strip().splitlines()),
+                         6)
+
+    def test_str_defaults_to_policy_max_line_length(self):
+        m = self._str_msg('Subject: long line' + ' ab'*50 + '\n\n')
+        self.assertEqual(len(str(m).strip().splitlines()), 3)
+
+    def test_str_defaults_to_utf8(self):
+        m = EmailMessage()
+        m['Subject'] = 'unicöde'
+        self.assertEqual(str(m), 'Subject: unicöde\n\n')
+
 
 class TestMIMEPart(TestEmailMessageBase, TestEmailBase):
     # Doing the full test run here may seem a bit redundant, since the two