Tests: switch to explicit u"unicode" literals

Drop `from __future__ import unicode_literals`;
it was there for Python 3.2 compatibility (which
Anymail doesn't support). Ensures tests use normal
strs in Python 2.x.

tests/test_mailgun_backend.py

@@ -1,7 +1,5 @@
 # -*- coding: utf-8 -*-
 
-from __future__ import unicode_literals
-
 from datetime import date, datetime
 from email.mime.base import MIMEBase
 from email.mime.image import MIMEImage
@@ -145,9 +143,7 @@ class MailgunBackendStandardEmailTests(MailgunBackendMockAPITestCase):
         self.assertEqual(len(inlines), 0)
 
     def test_unicode_attachment_correctly_decoded(self):
-        # Slight modification from the Django unicode docs:
-        # https://django.readthedocs.io/en/latest/ref/unicode.html#email
-        self.message.attach("Une pièce jointe.html", '<p>\u2019</p>', mimetype='text/html')
+        self.message.attach(u"Une pièce jointe.html", u'<p>\u2019</p>', mimetype='text/html')
         self.message.send()
         files = self.get_api_call_files()
         attachments = [value for (field, value) in files if field == 'attachment']

tests/test_mailgun_integration.py

@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import os
 import logging
 import unittest

tests/test_mandrill_backend.py

@@ -1,7 +1,5 @@
 # -*- coding: utf-8 -*-
 
-from __future__ import unicode_literals
-
 from datetime import date, datetime
 from decimal import Decimal
 from email.mime.base import MIMEBase
@@ -171,9 +169,7 @@ class MandrillBackendStandardEmailTests(MandrillBackendMockAPITestCase):
         self.assertFalse('images' in data['message'])
 
     def test_unicode_attachment_correctly_decoded(self):
-        # Slight modification from the Django unicode docs:
-        # https://django.readthedocs.io/en/latest/ref/unicode.html#email
-        self.message.attach("Une pièce jointe.html", '<p>\u2019</p>', mimetype='text/html')
+        self.message.attach(u"Une pièce jointe.html", u'<p>\u2019</p>', mimetype='text/html')
         self.message.send()
         data = self.get_api_call_json()
         attachments = data['message']['attachments']

tests/test_mandrill_integration.py

@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import os
 import unittest
 

tests/test_postmark_backend.py

@@ -1,7 +1,5 @@
 # -*- coding: utf-8 -*-
 
-from __future__ import unicode_literals
-
 from base64 import b64encode
 from decimal import Decimal
 from email.mime.base import MIMEBase
@@ -172,15 +170,13 @@ class PostmarkBackendStandardEmailTests(PostmarkBackendMockAPITestCase):
         self.assertNotIn('ContentID', attachments[2])
 
     def test_unicode_attachment_correctly_decoded(self):
-        # Slight modification from the Django unicode docs:
-        # https://django.readthedocs.io/en/latest/ref/unicode.html#email
-        self.message.attach("Une pièce jointe.html", '<p>\u2019</p>', mimetype='text/html')
+        self.message.attach(u"Une pièce jointe.html", u'<p>\u2019</p>', mimetype='text/html')
         self.message.send()
         data = self.get_api_call_json()
         self.assertEqual(data['Attachments'], [{
-            'Name': 'Une pièce jointe.html',
+            'Name': u'Une pièce jointe.html',
             'ContentType': 'text/html',
-            'Content': b64encode('<p>\u2019</p>'.encode('utf-8')).decode('ascii')
+            'Content': b64encode(u'<p>\u2019</p>'.encode('utf-8')).decode('ascii')
         }])
 
     def test_embedded_images(self):

tests/test_postmark_integration.py

@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import unittest
 
 from django.test import SimpleTestCase

tests/test_sendgrid_backend.py

@@ -1,7 +1,5 @@
 # -*- coding: utf-8 -*-
 
-from __future__ import unicode_literals
-
 import json
 from calendar import timegm
 from datetime import date, datetime
@@ -220,13 +218,11 @@ class SendGridBackendStandardEmailTests(SendGridBackendMockAPITestCase):
             self.message.send()
 
     def test_unicode_attachment_correctly_decoded(self):
-        # Slight modification from the Django unicode docs:
-        # https://django.readthedocs.io/en/latest/ref/unicode.html#email
-        self.message.attach("Une pièce jointe.html", '<p>\u2019</p>', mimetype='text/html')
+        self.message.attach(u"Une pièce jointe.html", u'<p>\u2019</p>', mimetype='text/html')
         self.message.send()
         files = self.get_api_call_files()
-        self.assertEqual(files['files[Une pièce jointe.html]'],
-                         ('Une pièce jointe.html', '<p>\u2019</p>', 'text/html'))
+        self.assertEqual(files[u'files[Une pièce jointe.html]'],
+                         (u'Une pièce jointe.html', u'<p>\u2019</p>', 'text/html'))
 
     def test_embedded_images(self):
         image_filename = SAMPLE_IMAGE_FILENAME

tests/test_sendgrid_integration.py

@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import os
 import unittest
 from datetime import datetime, timedelta

tests/test_sparkpost_backend.py

@@ -210,7 +210,7 @@ class SparkPostBackendStandardEmailTests(SparkPostBackendMockAPITestCase):
     def test_unicode_attachment_correctly_decoded(self):
         # Slight modification from the Django unicode docs:
         # http://django.readthedocs.org/en/latest/ref/unicode.html#email
-        self.message.attach("Une pièce jointe.html", '<p>\u2019</p>', mimetype='text/html')
+        self.message.attach(u"Une pièce jointe.html", u'<p>\u2019</p>', mimetype='text/html')
         self.message.send()
         params = self.get_send_params()
         attachments = params['attachments']

tests/test_sparkpost_integration.py

@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import os
 import unittest
 from datetime import datetime, timedelta