Fix TestBytesGeneratorIdempotent tests and a couple bugs they revealed.

The tests that were failing on (some) windows machines, where the
msg_XX.txt files used native \r\n lineseps are now also run on machines
that use \n natively, and conversely the \n tests are run on Windows.
The failing tests revealed one place where linesep needed to be added
to a flatten call in generator.  There was also another that the tests
didn't catch, so I added a test for that case as well.

Lib/email/generator.py

@@ -274,7 +274,7 @@ class Generator:
         for part in msg.get_payload():
             s = self._new_buffer()
             g = self.clone(s)
-            g.flatten(part, unixfrom=False)
+            g.flatten(part, unixfrom=False, linesep=self._NL)
             text = s.getvalue()
             lines = text.split(self._encoded_NL)
             # Strip off the unnecessary trailing empty line
@@ -301,7 +301,7 @@ class Generator:
         # in that case we just emit the string body.
         payload = msg.get_payload()
         if isinstance(payload, list):
-            g.flatten(msg.get_payload(0), unixfrom=False)
+            g.flatten(msg.get_payload(0), unixfrom=False, linesep=self._NL)
             payload = s.getvalue()
         self._fp.write(payload)
 

Lib/email/test/test_email.py

@@ -3,6 +3,7 @@
 # email package unit tests
 
 import os
+import re
 import sys
 import time
 import base64
@@ -1974,17 +1975,20 @@ message 2
 # should be identical.  Note: that we ignore the Unix-From since that may
 # contain a changed date.
 class TestIdempotent(TestEmailBase):
+
+    linesep = '\n'
+
     def _msgobj(self, filename):
         with openfile(filename) as fp:
             data = fp.read()
         msg = email.message_from_string(data)
         return msg, data
 
-    def _idempotent(self, msg, text):
+    def _idempotent(self, msg, text, unixfrom=False):
         eq = self.ndiffAssertEqual
         s = StringIO()
         g = Generator(s, maxheaderlen=0)
-        g.flatten(msg)
+        g.flatten(msg, unixfrom=unixfrom)
         eq(text, s.getvalue())
 
     def test_parse_text_message(self):
@@ -2071,6 +2075,10 @@ class TestIdempotent(TestEmailBase):
         msg, text = self._msgobj('msg_36.txt')
         self._idempotent(msg, text)
 
+    def test_message_delivery_status(self):
+        msg, text = self._msgobj('msg_43.txt')
+        self._idempotent(msg, text, unixfrom=True)
+
     def test_message_signed_idempotent(self):
         msg, text = self._msgobj('msg_45.txt')
         self._idempotent(msg, text)
@@ -2087,16 +2095,16 @@ class TestIdempotent(TestEmailBase):
             params[pk] = pv
         eq(params['report-type'], 'delivery-status')
         eq(params['boundary'], 'D1690A7AC1.996856090/mail.example.com')
-        eq(msg.preamble, 'This is a MIME-encapsulated message.\n')
-        eq(msg.epilogue, '\n')
+        eq(msg.preamble, 'This is a MIME-encapsulated message.' + self.linesep)
+        eq(msg.epilogue, self.linesep)
         eq(len(msg.get_payload()), 3)
         # Make sure the subparts are what we expect
         msg1 = msg.get_payload(0)
         eq(msg1.get_content_type(), 'text/plain')
-        eq(msg1.get_payload(), 'Yadda yadda yadda\n')
+        eq(msg1.get_payload(), 'Yadda yadda yadda' + self.linesep)
         msg2 = msg.get_payload(1)
         eq(msg2.get_content_type(), 'text/plain')
-        eq(msg2.get_payload(), 'Yadda yadda yadda\n')
+        eq(msg2.get_payload(), 'Yadda yadda yadda' + self.linesep)
         msg3 = msg.get_payload(2)
         eq(msg3.get_content_type(), 'message/rfc822')
         self.assertTrue(isinstance(msg3, Message))
@@ -2105,7 +2113,7 @@ class TestIdempotent(TestEmailBase):
         eq(len(payload), 1)
         msg4 = payload[0]
         unless(isinstance(msg4, Message))
-        eq(msg4.get_payload(), 'Yadda yadda yadda\n')
+        eq(msg4.get_payload(), 'Yadda yadda yadda' + self.linesep)
 
     def test_parser(self):
         eq = self.assertEqual
@@ -2122,7 +2130,7 @@ class TestIdempotent(TestEmailBase):
         self.assertTrue(isinstance(msg1, Message))
         eq(msg1.get_content_type(), 'text/plain')
         self.assertTrue(isinstance(msg1.get_payload(), str))
-        eq(msg1.get_payload(), '\n')
+        eq(msg1.get_payload(), self.linesep)
 
 
 
@@ -2955,28 +2963,42 @@ class Test8BitBytesHandling(unittest.TestCase):
     maxDiff = None
 
 
-class TestBytesGeneratorIdempotent(TestIdempotent):
+class BaseTestBytesGeneratorIdempotent:
 
     maxDiff = None
 
     def _msgobj(self, filename):
         with openfile(filename, 'rb') as fp:
             data = fp.read()
+        data = self.normalize_linesep_regex.sub(self.blinesep, data)
         msg = email.message_from_bytes(data)
         return msg, data
 
-    def _idempotent(self, msg, data):
-        # 13 = b'\r'
-        linesep = '\r\n' if data[data.index(b'\n')-1] == 13 else '\n'
+    def _idempotent(self, msg, data, unixfrom=False):
         b = BytesIO()
         g = email.generator.BytesGenerator(b, maxheaderlen=0)
-        g.flatten(msg, linesep=linesep)
+        g.flatten(msg, unixfrom=unixfrom, linesep=self.linesep)
         self.assertByteStringsEqual(data, b.getvalue())
 
     def assertByteStringsEqual(self, str1, str2):
+        # Not using self.blinesep here is intentional.  This way the output
+        # is more useful when the failure results in mixed line endings.
         self.assertListEqual(str1.split(b'\n'), str2.split(b'\n'))
 
 
+class TestBytesGeneratorIdempotentNL(BaseTestBytesGeneratorIdempotent,
+                                    TestIdempotent):
+    linesep = '\n'
+    blinesep = b'\n'
+    normalize_linesep_regex = re.compile(br'\r\n')
+
+
+class TestBytesGeneratorIdempotentCRLF(BaseTestBytesGeneratorIdempotent,
+                                       TestIdempotent):
+    linesep = '\r\n'
+    blinesep = b'\r\n'
+    normalize_linesep_regex = re.compile(br'(?<!\r)\n')
+
 
 class TestBase64(unittest.TestCase):
     def test_len(self):