Update string formatters to new style

Changing `%` style string formatters to `.format()`.
Leaving `logging` strings in old style for Python 2 compatibility.

Resolves: Issue #541

17 files changed, 98 insertions, 88 deletions

diff --git a/oauth2client/_helpers.py b/oauth2client/_helpers.py
index 2b86d01..cb959c5 100644
--- a/oauth2client/_helpers.py
+++ b/oauth2client/_helpers.py
@@ -68,7 +68,7 @@ def _to_bytes(value, encoding='ascii'):
     if isinstance(result, six.binary_type):
         return result
     else:
-        raise ValueError('%r could not be converted to bytes' % (value,))
+        raise ValueError('{0!r} could not be converted to bytes'.format(value))
 
 
 def _from_bytes(value):
@@ -89,7 +89,8 @@ def _from_bytes(value):
     if isinstance(result, six.text_type):
         return result
     else:
-        raise ValueError('%r could not be converted to unicode' % (value,))
+        raise ValueError(
+            '{0!r} could not be converted to unicode'.format(value))
 
 
 def _urlsafe_b64encode(raw_bytes):
diff --git a/oauth2client/client.py b/oauth2client/client.py
index fafa8c0..1d89a10 100644
--- a/oauth2client/client.py
+++ b/oauth2client/client.py
@@ -927,7 +927,7 @@ class OAuth2Credentials(Credentials):
             # An {'error':...} response body means the token is expired or
             # revoked, so we flag the credentials as such.
             logger.info('Failed to retrieve access token: %s', content)
-            error_msg = 'Invalid response %s.' % (resp['status'],)
+            error_msg = 'Invalid response {0}.'.format(resp['status'])
             try:
                 d = json.loads(content)
                 if 'error' in d:
@@ -972,7 +972,7 @@ class OAuth2Credentials(Credentials):
         if resp.status == http_client.OK:
             self.invalid = True
         else:
-            error_msg = 'Invalid response %s.' % resp.status
+            error_msg = 'Invalid response {0}.'.format(resp.status)
             try:
                 d = json.loads(_from_bytes(content))
                 if 'error' in d:
@@ -1018,7 +1018,7 @@ class OAuth2Credentials(Credentials):
             d = json.loads(content)
             self.scopes = set(util.string_to_scopes(d.get('scope', '')))
         else:
-            error_msg = 'Invalid response %s.' % (resp.status,)
+            error_msg = 'Invalid response {0}.'.format(resp.status)
             try:
                 d = json.loads(content)
                 if 'error_description' in d:
@@ -1459,7 +1459,8 @@ def save_to_well_known_file(credentials, well_known_file=None):
 
     config_dir = os.path.dirname(well_known_file)
     if not os.path.isdir(config_dir):
-        raise OSError('Config directory does not exist: %s' % config_dir)
+        raise OSError(
+            'Config directory does not exist: {0}'.format(config_dir))
 
     credentials_data = credentials.serialization_data
     _save_private_file(well_known_file, credentials_data)
@@ -1690,7 +1691,7 @@ def verify_id_token(id_token, audience, http=None,
         certs = json.loads(_from_bytes(content))
         return crypt.verify_signed_jwt_with_certs(id_token, certs, audience)
     else:
-        raise VerifyJwtTokenError('Status code: %d' % resp.status)
+        raise VerifyJwtTokenError('Status code: {0}'.format(resp.status))
 
 
 def _extract_id_token(id_token):
@@ -1711,7 +1712,7 @@ def _extract_id_token(id_token):
 
     if len(segments) != 3:
         raise VerifyJwtTokenError(
-            'Wrong number of segments in token: %s' % id_token)
+            'Wrong number of segments in token: {0}'.format(id_token))
 
     return json.loads(_from_bytes(_urlsafe_b64decode(segments[1])))
 
@@ -2036,15 +2037,15 @@ class OAuth2WebServerFlow(Flow):
                 flow_info = json.loads(content)
             except ValueError as exc:
                 raise OAuth2DeviceCodeError(
-                    'Could not parse server response as JSON: "%s", '
-                    'error: "%s"' % (content, exc))
+                    'Could not parse server response as JSON: "{0}", '
+                    'error: "{1}"'.format(content, exc))
             return DeviceFlowInfo.FromResponse(flow_info)
         else:
-            error_msg = 'Invalid response %s.' % (resp.status,)
+            error_msg = 'Invalid response {0}.'.format(resp.status)
             try:
                 error_dict = json.loads(content)
                 if 'error' in error_dict:
-                    error_msg += ' Error: %s' % (error_dict['error'],)
+                    error_msg += ' Error: {0}'.format(error_dict['error'])
             except ValueError:
                 # Couldn't decode a JSON response, stick with the
                 # default message.
@@ -2144,7 +2145,7 @@ class OAuth2WebServerFlow(Flow):
                 error_msg = (str(d['error']) +
                              str(d.get('error_description', '')))
             else:
-                error_msg = 'Invalid response: %s.' % str(resp.status)
+                error_msg = 'Invalid response: {0}.'.format(str(resp.status))
             raise FlowExchangeError(error_msg)
 
 
@@ -2218,4 +2219,4 @@ def flow_from_clientsecrets(filename, scope, redirect_uri=None,
             raise
     else:
         raise UnknownClientSecretsFlowError(
-            'This OAuth 2.0 flow is unsupported: %r' % (client_type,))
+            'This OAuth 2.0 flow is unsupported: {0!r}'.format(client_type))
diff --git a/oauth2client/clientsecrets.py b/oauth2client/clientsecrets.py
index 2c69d7e..4b43e66 100644
--- a/oauth2client/clientsecrets.py
+++ b/oauth2client/clientsecrets.py
@@ -93,17 +93,17 @@ def _validate_clientsecrets(clientsecrets_dict):
 
     if client_type not in VALID_CLIENT:
         raise InvalidClientSecretsError(
-            'Unknown client type: %s.' % (client_type,))
+            'Unknown client type: {0}.'.format(client_type))
 
     for prop_name in VALID_CLIENT[client_type]['required']:
         if prop_name not in client_info:
             raise InvalidClientSecretsError(
-                'Missing property "%s" in a client type of "%s".' %
-                (prop_name, client_type))
+                'Missing property "{0}" in a client type of "{1}".'.format(
+                    prop_name, client_type))
     for prop_name in VALID_CLIENT[client_type]['string']:
         if client_info[prop_name].startswith('[['):
             raise InvalidClientSecretsError(
-                'Property "%s" is not configured.' % prop_name)
+                'Property "{0}" is not configured.'.format(prop_name))
     return client_type, client_info
 
 
diff --git a/oauth2client/contrib/_appengine_ndb.py b/oauth2client/contrib/_appengine_ndb.py
index 44c0dac..c863e8f 100644
--- a/oauth2client/contrib/_appengine_ndb.py
+++ b/oauth2client/contrib/_appengine_ndb.py
@@ -76,9 +76,9 @@ class FlowNDBProperty(ndb.PickleProperty):
         """
         _LOGGER.info('validate: Got type %s', type(value))
         if value is not None and not isinstance(value, client.Flow):
-            raise TypeError('Property %s must be convertible to a flow '
-                            'instance; received: %s.' % (self._name,
-                                                         value))
+            raise TypeError(
+                'Property {0} must be convertible to a flow '
+                'instance; received: {1}.'.format(self._name, value))
 
 
 class CredentialsNDBProperty(ndb.BlobProperty):
@@ -104,9 +104,9 @@ class CredentialsNDBProperty(ndb.BlobProperty):
         """
         _LOGGER.info('validate: Got type %s', type(value))
         if value is not None and not isinstance(value, client.Credentials):
-            raise TypeError('Property %s must be convertible to a '
-                            'credentials instance; received: %s.' %
-                            (self._name, value))
+            raise TypeError(
+                'Property {0} must be convertible to a credentials '
+                'instance; received: {1}.'.format(self._name, value))
 
     def _to_base_type(self, value):
         """Converts our validated value to a JSON serialized string.
diff --git a/oauth2client/contrib/_fcntl_opener.py b/oauth2client/contrib/_fcntl_opener.py
index 9edfec2..754196d 100644
--- a/oauth2client/contrib/_fcntl_opener.py
+++ b/oauth2client/contrib/_fcntl_opener.py
@@ -39,8 +39,8 @@ class _FcntlOpener(_Opener):
                                               link.
         """
         if self._locked:
-            raise AlreadyLockedException('File %s is already locked' %
-                                         self._filename)
+            raise AlreadyLockedException(
+                'File {0} is already locked'.format(self._filename))
         start_time = time.time()
 
         validate_file(self._filename)
diff --git a/oauth2client/contrib/_win32_opener.py b/oauth2client/contrib/_win32_opener.py
index 4a0580e..aa14401 100644
--- a/oauth2client/contrib/_win32_opener.py
+++ b/oauth2client/contrib/_win32_opener.py
@@ -50,8 +50,8 @@ class _Win32Opener(_Opener):
                                               link.
         """
         if self._locked:
-            raise AlreadyLockedException('File %s is already locked' %
-                                         self._filename)
+            raise AlreadyLockedException(
+                'File {0} is already locked'.format(self._filename))
         start_time = time.time()
 
         validate_file(self._filename)
@@ -86,8 +86,8 @@ class _Win32Opener(_Opener):
 
                 # We could not acquire the lock. Try again.
                 if (time.time() - start_time) >= timeout:
-                    logger.warn('Could not lock %s in %s seconds' % (
-                        self._filename, timeout))
+                    logger.warn('Could not lock %s in %s seconds',
+                                self._filename, timeout)
                     if self._fh:
                         self._fh.close()
                     self._fh = open(self._filename, self._fallback_mode)
diff --git a/oauth2client/contrib/appengine.py b/oauth2client/contrib/appengine.py
index 8096439..513825a 100644
--- a/oauth2client/contrib/appengine.py
+++ b/oauth2client/contrib/appengine.py
@@ -251,9 +251,9 @@ class FlowProperty(db.Property):
 
     def validate(self, value):
         if value is not None and not isinstance(value, Flow):
-            raise db.BadValueError('Property %s must be convertible '
-                                   'to a FlowThreeLegged instance (%s)' %
-                                   (self.name, value))
+            raise db.BadValueError(
+                'Property {0} must be convertible '
+                'to a FlowThreeLegged instance ({1})'.format(self.name, value))
         return super(FlowProperty, self).validate(value)
 
     def empty(self, value):
@@ -298,9 +298,9 @@ class CredentialsProperty(db.Property):
         value = super(CredentialsProperty, self).validate(value)
         logger.info("validate: Got type " + str(type(value)))
         if value is not None and not isinstance(value, Credentials):
-            raise db.BadValueError('Property %s must be convertible '
-                                   'to a Credentials instance (%s)' %
-                                   (self.name, value))
+            raise db.BadValueError(
+                'Property {0} must be convertible '
+                'to a Credentials instance ({1})'.format(self.name, value))
         return value
 
 
@@ -356,8 +356,8 @@ class StorageByKeyName(Storage):
             elif issubclass(self._model, db.Model):
                 return False
 
-        raise TypeError('Model class not an NDB or DB model: %s.' %
-                        (self._model,))
+        raise TypeError(
+            'Model class not an NDB or DB model: {0}.'.format(self._model))
 
     def _get_entity(self):
         """Retrieve entity from datastore.
@@ -790,8 +790,8 @@ class OAuth2Decorator(object):
                 if error:
                     errormsg = self.request.get('error_description', error)
                     self.response.out.write(
-                        'The authorization request failed: %s' %
-                        _safe_html(errormsg))
+                        'The authorization request failed: {0}'.format(
+                            _safe_html(errormsg)))
                 else:
                     user = users.get_current_user()
                     decorator._create_flow(self)
diff --git a/oauth2client/contrib/devshell.py b/oauth2client/contrib/devshell.py
index b489c10..83a0578 100644
--- a/oauth2client/contrib/devshell.py
+++ b/oauth2client/contrib/devshell.py
@@ -83,7 +83,7 @@ def _SendRecv():
     sock.connect(('localhost', port))
 
     data = CREDENTIAL_INFO_REQUEST_JSON
-    msg = '%s\n%s' % (len(data), data)
+    msg = '{0}\n{1}'.format(len(data), data)
     sock.sendall(_to_bytes(msg, encoding='utf-8'))
 
     header = sock.recv(6).decode()
diff --git a/oauth2client/contrib/django_util/__init__.py b/oauth2client/contrib/django_util/__init__.py
index 4718da2..8a09d4a 100644
--- a/oauth2client/contrib/django_util/__init__.py
+++ b/oauth2client/contrib/django_util/__init__.py
@@ -106,7 +106,8 @@ request.oauth
                     http=request.oauth.http,
                    developerKey=API_KEY)
       events = service.events().list(calendarId='primary').execute()['items']
-      return HttpResponse("email: %s , calendar: %s" % (email, str(events)))
+      return HttpResponse(
+          "email: {0} , calendar: {1}".format(email, str(events)))
 
 To make OAuth2 optional and provide an authorization link in your own views.
 
@@ -121,12 +122,12 @@ To make OAuth2 optional and provide an authorization link in your own views.
        if request.oauth.has_credentials():
            # this could be passed into a view
            # request.oauth.http is also initialized
-           return HttpResponse("User email: %s"
-            % request.oauth.credentials.id_token['email'])
+           return HttpResponse("User email: {0}".format(
+               request.oauth.credentials.id_token['email']))
        else:
            return HttpResponse(
-               'Here is an OAuth Authorize link: <a href="%s">Authorize</a>'
-                % request.oauth.get_authorize_redirect())
+               'Here is an OAuth Authorize link: <a href="{0}">Authorize'
+               '</a>'.format(request.oauth.get_authorize_redirect()))
 
 If a view needs a scope not included in the default scopes specified in
 the settings, you can use [incremental auth](https://developers.google.com/identity/sign-in/web/incremental-auth)
@@ -146,8 +147,8 @@ and specify additional scopes in the decorator arguments.
            return HttpResponse(str(events))
        else:
            return HttpResponse(
-               'Here is an OAuth Authorize link: <a href="%s">Authorize</a>'
-                % request.oauth.get_authorize_redirect())
+               'Here is an OAuth Authorize link: <a href="{0}">Authorize'
+               '</a>'.format(request.oauth.get_authorize_redirect()))
 
 
 To provide a callback on authorization being completed, use the
@@ -160,7 +161,8 @@ oauth2_authorized signal:
    from oauth2client.contrib.django_util.signals import oauth2_authorized
 
    def test_callback(sender, request, credentials, **kwargs):
-       print "Authorization Signal Received %s" % credentials.id_token['email']
+       print("Authorization Signal Received {0}".format(
+               credentials.id_token['email']))
 
    oauth2_authorized.connect(test_callback)
 
diff --git a/oauth2client/contrib/django_util/decorators.py b/oauth2client/contrib/django_util/decorators.py
index 26c3216..7b598b2 100644
--- a/oauth2client/contrib/django_util/decorators.py
+++ b/oauth2client/contrib/django_util/decorators.py
@@ -37,7 +37,8 @@ def oauth_required(decorated_function=None, scopes=None, **decorator_kwargs):
                        developerKey=API_KEY)
           events = service.events().list(
                                     calendarId='primary').execute()['items']
-          return HttpResponse("email: %s, calendar: %s" % (email, str(events)))
+          return HttpResponse(
+              "email: {0}, calendar: {1}".format(email, str(events)))
 
     :param decorated_function: View function to decorate, must have the Django
            request object as the first argument
@@ -85,12 +86,12 @@ def oauth_enabled(decorated_function=None, scopes=None, **decorator_kwargs):
            if request.oauth.has_credentials():
                # this could be passed into a view
                # request.oauth.http is also initialized
-               return HttpResponse("User email: %s" %
-                                   request.oauth.credentials.id_token['email'])
+               return HttpResponse("User email: {0}".format(
+                                   request.oauth.credentials.id_token['email']))
            else:
                return HttpResponse('Here is an OAuth Authorize link:
-               <a href="%s">Authorize</a>' %
-               request.oauth.get_authorize_redirect())
+               <a href="{0}">Authorize</a>'.format(
+                   request.oauth.get_authorize_redirect()))
 
 
     :param decorated_function: View function to decorate
diff --git a/oauth2client/contrib/django_util/views.py b/oauth2client/contrib/django_util/views.py
index de8df07..3f1ae42 100644
--- a/oauth2client/contrib/django_util/views.py
+++ b/oauth2client/contrib/django_util/views.py
@@ -77,7 +77,7 @@ def oauth2_callback(request):
         reason = request.GET.get(
             'error_description', request.GET.get('error', ''))
         return http.HttpResponseBadRequest(
-            'Authorization failed %s' % reason)
+            'Authorization failed {0}'.format(reason))
 
     try:
         encoded_state = request.GET['state']
diff --git a/oauth2client/contrib/locked_file.py b/oauth2client/contrib/locked_file.py
index ab7de2b..0d28ebb 100644
--- a/oauth2client/contrib/locked_file.py
+++ b/oauth2client/contrib/locked_file.py
@@ -57,7 +57,7 @@ class AlreadyLockedException(Exception):
 def validate_file(filename):
     if os.path.islink(filename):
         raise CredentialsFileSymbolicLinkError(
-            'File: %s is a symbolic link.' % filename)
+            'File: {0} is a symbolic link.'.format(filename))
 
 
 class _Opener(object):
@@ -122,8 +122,8 @@ class _PosixOpener(_Opener):
             CredentialsFileSymbolicLinkError if the file is a symbolic link.
         """
         if self._locked:
-            raise AlreadyLockedException('File %s is already locked' %
-                                         self._filename)
+            raise AlreadyLockedException(
+                'File {0} is already locked'.format(self._filename))
         self._locked = False
 
         validate_file(self._filename)
@@ -170,7 +170,7 @@ class _PosixOpener(_Opener):
 
     def _posix_lockfile(self, filename):
         """The name of the lock file to use for posix locking."""
-        return '%s.lock' % filename
+        return '{0}.lock'.format(filename)
 
 
 class LockedFile(object):
diff --git a/oauth2client/contrib/multistore_file.py b/oauth2client/contrib/multistore_file.py
index 3c96eb1..9ad7a6f 100644
--- a/oauth2client/contrib/multistore_file.py
+++ b/oauth2client/contrib/multistore_file.py
@@ -390,8 +390,8 @@ class _MultiStore(object):
                         'corrupt or an old version. Overwriting.')
         if version > 1:
             raise NewerCredentialStoreError(
-                'Credential file has file_version of %d. '
-                'Only file_version of 1 is supported.' % version)
+                'Credential file has file_version of {0}. '
+                'Only file_version of 1 is supported.'.format(version))
 
         credentials = []
         try:
diff --git a/oauth2client/crypt.py b/oauth2client/crypt.py
index 70bef8c..14eb4ef 100644
--- a/oauth2client/crypt.py
+++ b/oauth2client/crypt.py
@@ -144,11 +144,11 @@ def _check_audience(payload_dict, audience):
 
     audience_in_payload = payload_dict.get('aud')
     if audience_in_payload is None:
-        raise AppIdentityError('No aud field in token: %s' %
-                               (payload_dict,))
+        raise AppIdentityError(
+            'No aud field in token: {0}'.format(payload_dict))
     if audience_in_payload != audience:
-        raise AppIdentityError('Wrong recipient, %s != %s: %s' %
-                               (audience_in_payload, audience, payload_dict))
+        raise AppIdentityError('Wrong recipient, {0} != {1}: {2}'.format(
+            audience_in_payload, audience, payload_dict))
 
 
 def _verify_time_range(payload_dict):
@@ -180,26 +180,28 @@ def _verify_time_range(payload_dict):
     # Make sure issued at and expiration are in the payload.
     issued_at = payload_dict.get('iat')
     if issued_at is None:
-        raise AppIdentityError('No iat field in token: %s' % (payload_dict,))
+        raise AppIdentityError(
+            'No iat field in token: {0}'.format(payload_dict))
     expiration = payload_dict.get('exp')
     if expiration is None:
-        raise AppIdentityError('No exp field in token: %s' % (payload_dict,))
+        raise AppIdentityError(
+            'No exp field in token: {0}'.format(payload_dict))
 
     # Make sure the expiration gives an acceptable token lifetime.
     if expiration >= now + MAX_TOKEN_LIFETIME_SECS:
-        raise AppIdentityError('exp field too far in future: %s' %
-                               (payload_dict,))
+        raise AppIdentityError(
+            'exp field too far in future: {0}'.format(payload_dict))
 
     # Make sure (up to clock skew) that the token wasn't issued in the future.
     earliest = issued_at - CLOCK_SKEW_SECS
     if now < earliest:
-        raise AppIdentityError('Token used too early, %d < %d: %s' %
-                               (now, earliest, payload_dict))
+        raise AppIdentityError('Token used too early, {0} < {1}: {2}'.format(
+            now, earliest, payload_dict))
     # Make sure (up to clock skew) that the token isn't already expired.
     latest = expiration + CLOCK_SKEW_SECS
     if now > latest:
-        raise AppIdentityError('Token used too late, %d > %d: %s' %
-                               (now, latest, payload_dict))
+        raise AppIdentityError('Token used too late, {0} > {1}: {2}'.format(
+            now, latest, payload_dict))
 
 
 def verify_signed_jwt_with_certs(jwt, certs, audience=None):
@@ -223,7 +225,7 @@ def verify_signed_jwt_with_certs(jwt, certs, audience=None):
 
     if jwt.count(b'.') != 2:
         raise AppIdentityError(
-            'Wrong number of segments in token: %s' % (jwt,))
+            'Wrong number of segments in token: {0}'.format(jwt))
 
     header, payload, signature = jwt.split(b'.')
     message_to_sign = header + b'.' + payload
@@ -234,7 +236,7 @@ def verify_signed_jwt_with_certs(jwt, certs, audience=None):
     try:
         payload_dict = json.loads(_from_bytes(payload_bytes))
     except:
-        raise AppIdentityError('Can\'t parse token: %s' % (payload_bytes,))
+        raise AppIdentityError('Can\'t parse token: {0}'.format(payload_bytes))
 
     # Verify that the signature matches the message.
     _verify_signature(message_to_sign, signature, certs.values())
diff --git a/oauth2client/file.py b/oauth2client/file.py
index d482359..5047937 100644
--- a/oauth2client/file.py
+++ b/oauth2client/file.py
@@ -42,7 +42,7 @@ class Storage(BaseStorage):
     def _validate_file(self):
         if os.path.islink(self._filename):
             raise CredentialsFileSymbolicLinkError(
-                'File: %s is a symbolic link.' % self._filename)
+                'File: {0} is a symbolic link.'.format(self._filename))
 
     def locked_get(self):
         """Retrieve Credential from file.
diff --git a/oauth2client/tools.py b/oauth2client/tools.py
index 499861e..8947157 100644
--- a/oauth2client/tools.py
+++ b/oauth2client/tools.py
@@ -42,7 +42,7 @@ _CLIENT_SECRETS_MESSAGE = """WARNING: Please configure OAuth 2.0
 To make this sample run you will need to populate the client_secrets.json file
 found at:
 
-   %s
+   {file_path}
 
 with information from the APIs Console <https://code.google.com/apis/console>.
 
@@ -60,7 +60,7 @@ authorization.
 _BROWSER_OPENED_MESSAGE = """
 Your browser has been opened to visit:
 
-    %s
+    {address}
 
 If your browser is on a different machine then exit and re-run this
 application with the command-line parameter
@@ -71,7 +71,7 @@ application with the command-line parameter
 _GO_TO_LINK_MESSAGE = """
 Go to the following link in your browser:
 
-    %s
+    {address}
 """
 
 
@@ -211,7 +211,8 @@ def run_flow(flow, storage, flags=None, http=None):
             print(_FAILED_START_MESSAGE)
 
     if not flags.noauth_local_webserver:
-        oauth_callback = 'http://%s:%s/' % (flags.auth_host_name, port_number)
+        oauth_callback = 'http://{host}:{port}/'.format(
+            host=flags.auth_host_name, port=port_number)
     else:
         oauth_callback = client.OOB_CALLBACK_URN
     flow.redirect_uri = oauth_callback
@@ -220,9 +221,9 @@ def run_flow(flow, storage, flags=None, http=None):
     if not flags.noauth_local_webserver:
         import webbrowser
         webbrowser.open(authorize_url, new=1, autoraise=True)
-        print(_BROWSER_OPENED_MESSAGE % authorize_url)
+        print(_BROWSER_OPENED_MESSAGE.format(address=authorize_url))
     else:
-        print(_GO_TO_LINK_MESSAGE % authorize_url)
+        print(_GO_TO_LINK_MESSAGE.format(address=authorize_url))
 
     code = None
     if not flags.noauth_local_webserver:
@@ -241,7 +242,7 @@ def run_flow(flow, storage, flags=None, http=None):
     try:
         credential = flow.step2_exchange(code, http=http)
     except client.FlowExchangeError as e:
-        sys.exit('Authentication has failed: %s' % e)
+        sys.exit('Authentication has failed: {0}'.format(e))
 
     storage.put(credential)
     credential.set_store(storage)
@@ -252,4 +253,4 @@ def run_flow(flow, storage, flags=None, http=None):
 
 def message_if_missing(filename):
     """Helpful message to display if the CLIENT_SECRETS file is missing."""
-    return _CLIENT_SECRETS_MESSAGE % filename
+    return _CLIENT_SECRETS_MESSAGE.format(file_path=filename)
diff --git a/oauth2client/util.py b/oauth2client/util.py
index 8c907d8..e3ba62b 100644
--- a/oauth2client/util.py
+++ b/oauth2client/util.py
@@ -124,10 +124,12 @@ def positional(max_positional_args):
                 plural_s = ''
                 if max_positional_args != 1:
                     plural_s = 's'
-                message = ('%s() takes at most %d positional '
-                           'argument%s (%d given)' % (
-                               wrapped.__name__, max_positional_args,
-                               plural_s, len(args)))
+                message = ('{function}() takes at most {args_max} positional '
+                           'argument{plural} ({args_given} given)'.format(
+                               function=wrapped.__name__,
+                               args_max=max_positional_args,
+                               args_given=len(args),
+                               plural=plural_s))
                 if positional_parameters_enforcement == POSITIONAL_EXCEPTION:
                     raise TypeError(message)
                 elif positional_parameters_enforcement == POSITIONAL_WARNING: