Fix jupyter#6256 : migrate to python 3.7+

* Update classifiers
* Update python_requires
* Fix deprecated code (some from python 2.x):
  - `io.open` -> `open`
  - `IOError` -> `OSError`  (in python 3 `IOError` is alias)
  - `socket.error` -> `OSError`
  - `u''` -> `''`
  - `str().format` -> f-strings
    (where it was quick automatically validated change)
  - `object` is not needed as base class
  - use `set` comprehensions
  - `sum` over generators (do not produce temporary lists)
  - use plain `super()`
* remove unused imports

docs/source/conf.py

@@ -319,7 +319,7 @@
 # -- Options for link checks ----------------------------------------------
 
 linkcheck_ignore = [
-    'http://127\.0\.0\.1/*'
+    r'http://127\.0\.0\.1/*'
 ]
 
 

notebook/__main__.py

@@ -1,4 +1,3 @@
-
 if __name__ == '__main__':
     from notebook import notebookapp as app
     app.launch_new_instance()

notebook/_sysinfo.py

@@ -55,10 +55,10 @@ def pkg_commit_hash(pkg_path):
             if repo_commit:
                 return 'repository', repo_commit.strip().decode('ascii')
             else:
-                return u'', u''
+                return '', ''
         par_path = p.dirname(par_path)
-                
-    return u'', u''
+
+    return '', ''
 
 
 def pkg_info(pkg_path):

notebook/auth/login.py

@@ -73,13 +73,13 @@ def hashed_password(self):
 
     def passwd_check(self, a, b):
         return passwd_check(a, b)
-    
+
     def post(self):
-        typed_password = self.get_argument('password', default=u'')
-        new_password = self.get_argument('new_password', default=u'')
+        typed_password = self.get_argument('password', default='')
+        new_password = self.get_argument('new_password', default='')
+
 
 
-
         if self.get_login_available(self.settings):
             if self.passwd_check(self.hashed_password, typed_password) and not new_password:
                 self.set_login_cookie(self, uuid.uuid4().hex)
@@ -112,7 +112,7 @@ def set_login_cookie(cls, handler, user_id=None):
         handler.set_secure_cookie(handler.cookie_name, user_id, **cookie_options)
         return user_id
 
-    auth_header_pat = re.compile('token\s+(.+)', re.IGNORECASE)
+    auth_header_pat = re.compile(r'token\s+(.+)', re.IGNORECASE)
 
     @classmethod
     def get_token(cls, handler):
@@ -197,7 +197,7 @@ def get_user(cls, handler):
     @classmethod
     def get_user_token(cls, handler):
         """Identify the user based on a token in the URL or Authorization header
-        
+
         Returns:
         - uuid if authenticated
         - None if not
@@ -245,7 +245,7 @@ def password_from_settings(cls, settings):
 
         If there is no configured password, an empty string will be returned.
         """
-        return settings.get('password', u'')
+        return settings.get('password', '')
 
     @classmethod
     def get_login_available(cls, settings):

notebook/auth/security.py

@@ -5,7 +5,6 @@
 from contextlib import contextmanager
 import getpass
 import hashlib
-import io
 import json
 import os
 import random
@@ -135,7 +134,7 @@ def passwd_check(hashed_passphrase, passphrase):
 def persist_config(config_file=None, mode=0o600):
     """Context manager that can be used to modify a config object
 
-    On exit of the context manager, the config will be written back to disk, 
+    On exit of the context manager, the config will be written back to disk,
     by default with user-only (600) permissions.
     """
 
@@ -152,7 +151,7 @@ def persist_config(config_file=None, mode=0o600):
 
     yield config
 
-    with io.open(config_file, 'w', encoding='utf8') as f:
+    with open(config_file, 'w', encoding='utf8') as f:
         f.write(cast_unicode(json.dumps(config, indent=2)))
 
     try:
@@ -165,7 +164,7 @@ def persist_config(config_file=None, mode=0o600):
 
 def set_password(password=None, config_file=None):
     """Ask user for password, store it in notebook json configuration file"""
-    
+
     hashed_password = passwd(password)
 
     with persist_config(config_file) as config:

notebook/auth/tests/test_security.py

@@ -18,8 +18,8 @@ def test_bad():
 
 def test_passwd_check_unicode():
     # GH issue #4524
-    phash = u'sha1:23862bc21dd3:7a415a95ae4580582e314072143d9c382c491e4f'
-    assert passwd_check(phash, u"łe¶ŧ←↓→")
-    phash = (u'argon2:$argon2id$v=19$m=10240,t=10,p=8$'
-             u'qjjDiZUofUVVnrVYxacnbA$l5pQq1bJ8zglGT2uXP6iOg')
-    assert passwd_check(phash, u"łe¶ŧ←↓→")
+    phash = 'sha1:23862bc21dd3:7a415a95ae4580582e314072143d9c382c491e4f'
+    assert passwd_check(phash, "łe¶ŧ←↓→")
+    phash = ('argon2:$argon2id$v=19$m=10240,t=10,p=8$'
+             'qjjDiZUofUVVnrVYxacnbA$l5pQq1bJ8zglGT2uXP6iOg')
+    assert passwd_check(phash, "łe¶ŧ←↓→")