Added query method to Account and backend classes to ask if account supports

notifications. Currently only IMAP supports notifications, but only if idle parameter 
is true.

Mailnag/backends/base.py

@@ -67,6 +67,11 @@ class MailboxBackend(object):
 		"""
 		raise NotImplementedError
 
+	def supports_notifications(self):
+		"""Returns True if mailbox supports notifications."""
+		# Default implementation
+		return False
+
 	@abstractmethod
 	def notify_next_change(self, callback=None, timeout=None):
 		"""Asks mailbox to notify next change.

Mailnag/backends/imap.py

@@ -40,7 +40,7 @@ class IMAPMailboxBackend(MailboxBackend):
 	"""Implementation of IMAP mail boxes."""
 
 	def __init__(self, name = '', user = '', password = '', oauth2string = '',
-				 server = '', port = '', ssl = True, folders = [], **kw):
+				 server = '', port = '', ssl = True, folders = [], idle=True, **kw):
 		self.name = name
 		self.user = user
 		self.password = password
@@ -49,6 +49,7 @@ class IMAPMailboxBackend(MailboxBackend):
 		self.port = port
 		self.ssl = ssl # bool
 		self.folders = [encode_mutf7(folder) for folder in folders]
+		self.idle = idle
 		self._conn = None
 
 
@@ -130,6 +131,11 @@ class IMAPMailboxBackend(MailboxBackend):
 		return lst
 
 
+	def supports_notifications(self):
+		"""Returns True if mailbox supports notifications.
+		IMAP mailbox supports notifications if idle parameter is True"""
+		return self.idle
+
 	def notify_next_change(self, callback=None, timeout=None):
 		self._ensure_open()
 		

Mailnag/common/accounts.py

@@ -116,6 +116,11 @@ class Account:
 		return self._get_backend().list_messages()
 
 
+	def supports_notifications(self):
+		"""Returns True if account supports notifications."""
+		return self._get_backend().supports_notifications()
+
+
 	def notify_next_change(self, callback=None, timeout=None):
 		"""Asks mailbox to notify next change.
 		Callback is called when new mail arrives or removed.

tests/test_account.py

@@ -22,6 +22,8 @@
 
 """Test cases for Account."""
 
+import pytest
+
 from Mailnag.common.accounts import Account
 
 
@@ -109,3 +111,18 @@ def test_account_should_configurable_with_any_parameters():
 	assert config['weird'] == 'odd'
 	assert config['odd'] == 'weird'
 
+
+@pytest.mark.parametrize("config,should_support", [
+	({'mailbox_type': 'imap', 'idle': True}, True),
+	({'mailbox_type': 'imap', 'idle': False}, False),
+	({'mailbox_type': 'pop3'}, False),
+	({'mailbox_type': 'mbox'}, False),
+	({'mailbox_type': 'maildir'}, False),
+])
+def test_account_supports_notifications(config, should_support):
+	account = Account(**config)
+	if should_support:
+		assert account.supports_notifications()
+	else:
+		assert not account.supports_notifications()
+