Added tests to the mongodb changefeed (#1035)

* Added tests to the mongodb changefeed

* pep8 and typo fixes

bigchaindb/backend/mongodb/changefeed.py

@@ -2,7 +2,7 @@ import logging
 import time
 
 import pymongo
-from pymongo.errors import ConnectionFailure, OperationFailure
+from pymongo import errors
 
 from bigchaindb import backend
 from bigchaindb.backend.changefeed import ChangeFeed
@@ -29,7 +29,9 @@ class MongoDBChangeFeed(ChangeFeed):
             try:
                 self.run_changefeed()
                 break
-            except (ConnectionFailure, OperationFailure) as exc:
+            except (errors.ConnectionFailure, errors.OperationFailure,
+                    errors.AutoReconnect,
+                    errors.ServerSelectionTimeoutError) as exc:
                 logger.exception(exc)
                 time.sleep(1)
 
@@ -76,8 +78,10 @@ class MongoDBChangeFeed(ChangeFeed):
                 # operations to apply to the document and not the
                 # document itself. So here we first read the document
                 # and then return it.
-                doc = self.connection.conn[dbname][table]\
-                        .find_one(record['o2'], projection={'_id': False})
+                doc = self.connection.conn[dbname][table].find_one(
+                    {'_id': record['o2']},
+                    {'_id': False}
+                )
                 self.outqueue.put(doc)
 
 

tests/backend/mongodb/test_changefeed.py

@@ -1 +1,169 @@
-"""MongoDB changefeed tests"""
+from unittest import mock
+
+import pytest
+from pymongo.errors import ConnectionFailure
+
+from multipipes import Pipe
+
+
+@pytest.fixture
+def mock_changefeed_data():
+    return [
+        {
+            'op': 'i',
+            'o': {'_id': '', 'msg': 'seems like we have an insert here'}
+        },
+        {
+            'op': 'd',
+            'o': {'msg': 'seems like we have a delete here'}
+        },
+        {
+            'op': 'u',
+            'o': {'msg': 'seems like we have an update here'},
+            'o2': 'some-id'
+        },
+    ]
+
+
+@pytest.mark.bdb
+@mock.patch('pymongo.cursor.Cursor.alive', new_callable=mock.PropertyMock)
+@mock.patch('pymongo.cursor.Cursor.next')
+def test_changefeed_insert(mock_cursor_next, mock_cursor_alive,
+                           mock_changefeed_data):
+    from bigchaindb.backend import get_changefeed, connect
+    from bigchaindb.backend.changefeed import ChangeFeed
+
+    # setup connection and mocks
+    conn = connect()
+    # changefeed.run_forever only returns when the cursor is closed
+    # so we mock `alive` to be False it finishes reading the mocked data
+    mock_cursor_alive.side_effect = [mock.DEFAULT, mock.DEFAULT,
+                                     mock.DEFAULT, mock.DEFAULT, False]
+    # mock the `next` method of the cursor to return the mocked data
+    mock_cursor_next.side_effect = [mock.DEFAULT] + mock_changefeed_data
+
+    outpipe = Pipe()
+    changefeed = get_changefeed(conn, 'backlog', ChangeFeed.INSERT)
+    changefeed.outqueue = outpipe
+    changefeed.run_forever()
+
+    assert outpipe.get()['msg'] == 'seems like we have an insert here'
+    assert outpipe.qsize() == 0
+
+
+@pytest.mark.bdb
+@mock.patch('pymongo.cursor.Cursor.alive', new_callable=mock.PropertyMock)
+@mock.patch('pymongo.cursor.Cursor.next')
+def test_changefeed_delete(mock_cursor_next, mock_cursor_alive,
+                           mock_changefeed_data):
+    from bigchaindb.backend import get_changefeed, connect
+    from bigchaindb.backend.changefeed import ChangeFeed
+
+    conn = connect()
+    mock_cursor_alive.side_effect = [mock.DEFAULT, mock.DEFAULT,
+                                     mock.DEFAULT, mock.DEFAULT, False]
+    mock_cursor_next.side_effect = [mock.DEFAULT] + mock_changefeed_data
+
+    outpipe = Pipe()
+    changefeed = get_changefeed(conn, 'backlog', ChangeFeed.DELETE)
+    changefeed.outqueue = outpipe
+    changefeed.run_forever()
+
+    assert outpipe.get()['msg'] == 'seems like we have a delete here'
+    assert outpipe.qsize() == 0
+
+
+@pytest.mark.bdb
+@mock.patch('pymongo.collection.Collection.find_one')
+@mock.patch('pymongo.cursor.Cursor.alive', new_callable=mock.PropertyMock)
+@mock.patch('pymongo.cursor.Cursor.next')
+def test_changefeed_update(mock_cursor_next, mock_cursor_alive,
+                           mock_cursor_find_one, mock_changefeed_data):
+    from bigchaindb.backend import get_changefeed, connect
+    from bigchaindb.backend.changefeed import ChangeFeed
+
+    conn = connect()
+    mock_cursor_alive.side_effect = [mock.DEFAULT, mock.DEFAULT,
+                                     mock.DEFAULT, mock.DEFAULT, False]
+    mock_cursor_next.side_effect = [mock.DEFAULT] + mock_changefeed_data
+    mock_cursor_find_one.return_value = mock_changefeed_data[2]['o']
+
+    outpipe = Pipe()
+    changefeed = get_changefeed(conn, 'backlog', ChangeFeed.UPDATE)
+    changefeed.outqueue = outpipe
+    changefeed.run_forever()
+
+    assert outpipe.get()['msg'] == 'seems like we have an update here'
+    assert outpipe.qsize() == 0
+    assert mock_cursor_find_one.called_once_with(
+        {'_id': mock_changefeed_data[2]['o']},
+        {'_id': False}
+    )
+
+
+@pytest.mark.bdb
+@mock.patch('pymongo.collection.Collection.find_one')
+@mock.patch('pymongo.cursor.Cursor.alive', new_callable=mock.PropertyMock)
+@mock.patch('pymongo.cursor.Cursor.next')
+def test_changefeed_multiple_operations(mock_cursor_next, mock_cursor_alive,
+                                        mock_cursor_find_one,
+                                        mock_changefeed_data):
+    from bigchaindb.backend import get_changefeed, connect
+    from bigchaindb.backend.changefeed import ChangeFeed
+
+    conn = connect()
+    mock_cursor_alive.side_effect = [mock.DEFAULT, mock.DEFAULT,
+                                     mock.DEFAULT, mock.DEFAULT, False]
+    mock_cursor_next.side_effect = [mock.DEFAULT] + mock_changefeed_data
+    mock_cursor_find_one.return_value = mock_changefeed_data[2]['o']
+
+    outpipe = Pipe()
+    changefeed = get_changefeed(conn, 'backlog',
+                                ChangeFeed.INSERT | ChangeFeed.UPDATE)
+    changefeed.outqueue = outpipe
+    changefeed.run_forever()
+
+    assert outpipe.get()['msg'] == 'seems like we have an insert here'
+    assert outpipe.get()['msg'] == 'seems like we have an update here'
+    assert outpipe.qsize() == 0
+
+
+@pytest.mark.bdb
+@mock.patch('pymongo.cursor.Cursor.alive', new_callable=mock.PropertyMock)
+@mock.patch('pymongo.cursor.Cursor.next')
+def test_changefeed_prefeed(mock_cursor_next, mock_cursor_alive,
+                            mock_changefeed_data):
+    from bigchaindb.backend import get_changefeed, connect
+    from bigchaindb.backend.changefeed import ChangeFeed
+
+    conn = connect()
+    mock_cursor_alive.side_effect = [mock.DEFAULT, mock.DEFAULT,
+                                     mock.DEFAULT, mock.DEFAULT, False]
+    mock_cursor_next.side_effect = [mock.DEFAULT] + mock_changefeed_data
+
+    outpipe = Pipe()
+    changefeed = get_changefeed(conn, 'backlog', ChangeFeed.INSERT,
+                                prefeed=[1, 2, 3])
+    changefeed.outqueue = outpipe
+    changefeed.run_forever()
+
+    assert outpipe.qsize() == 4
+
+
+@pytest.mark.bdb
+@mock.patch('pymongo.cursor.Cursor.alive', new_callable=mock.PropertyMock)
+@mock.patch('bigchaindb.backend.mongodb.changefeed.MongoDBChangeFeed.run_changefeed')  # noqa
+def test_connection_failure(mock_run_changefeed, mock_cursor_alive):
+    from bigchaindb.backend import get_changefeed, connect
+    from bigchaindb.backend.changefeed import ChangeFeed
+
+    conn = connect()
+    mock_cursor_alive.return_value = False
+    mock_run_changefeed.side_effect = [ConnectionFailure(), mock.DEFAULT]
+
+    changefeed = get_changefeed(conn, 'backlog', ChangeFeed.INSERT)
+    changefeed.run_forever()
+
+    # run_changefeed raises an exception the first time its called and then
+    # it's called again
+    assert mock_run_changefeed.call_count == 2