Replace connection property with acquire/release methods; Updated system_tests - coverage ~96%; Added .coveragerc; Remove helpless unittests, keep only system tests

Author: prawn-cake

.coveragerc

@@ -9,7 +9,6 @@ exclude_lines =
 
     # Don't complain about missing debug-only code:
     def __repr__
-    def __unicode__
     if self\.debug
 
     # Don't complain if tests don't hit defensive assertion code:
@@ -23,9 +22,9 @@ exclude_lines =
 include =
     pgclient/*
 omit =
-    pgclient/tests.py
+    pgclient/system_test/*
 
 ignore_errors = True
 
 [html]
-directory = coverage_html_report
+directory = coverage_html_report

pgclient/client.py

@@ -12,38 +12,48 @@ def __init__(self, dsn=None, database=None, user=None, password=None,
         self.dsn = dsn
 
         # Pass connection params as is
-        conn_params = dict(dsn=dsn, database=database, user=user,
-                           password=password, host=host, port=port)
+        conn_params = dict(dsn=dsn,
+                           database=database,
+                           user=user,
+                           password=password,
+                           host=host,
+                           port=port)
         if pool_size < 1:
             raise ValueError('Wrong pool_size value. Must be >= 1. '
                              'Current: {}'.format(pool_size))
         # Init thread-safe connection pool
         self._pool = pgpool.ThreadedConnectionPool(
             minconn=1, maxconn=pool_size, **conn_params)
 
-    @property
-    def _connection(self):
-        """Acquire pool connection property
+    def acquire_conn(self):
+        """Get new pool connection
 
-        :return: postgresql connection instance
+        :return: psycopg2 connection object
         """
         return self._pool.getconn()
 
+    def release_conn(self, conn):
+        """Release connection to a pool
+
+        :param conn: psycopg2 connection object
+        """
+        self._pool.putconn(conn)
+
     @contextmanager
     def _get_cursor(self, cursor_factory=None):
         """Get connection cursor context manager
 
         :param cursor_factory: pg_extras.* cursor factory class
         """
-        conn = self._connection
+        conn = self.acquire_conn()
         try:
             yield conn.cursor(cursor_factory=cursor_factory)
             conn.commit()
         except psycopg2.DatabaseError as err:
             conn.rollback()
             raise psycopg2.DatabaseError(err.message)
         finally:
-            self._pool.putconn(conn)
+            self.release_conn(conn)
 
     @property
     def cursor(self):

pgclient/system_test/system_test.py

@@ -5,6 +5,7 @@
 import os
 import os.path as op
 import psycopg2
+from psycopg2.pool import PoolError
 
 sys.path.append(
     op.abspath(op.dirname(__file__)) + '/../'
@@ -24,12 +25,14 @@ class PostgresClientSystemTest(unittest.TestCase):
     DB_NAME = 'test'
     DB_PORT = os.environ.get('POSTGRES_PORT', 5432)
     TABLE_NAME = 'users'
+    POOL_SIZE = 3
 
     def setUp(self):
-        dsn = 'user={} password={} dbname={} host=localhost port={}'.format(
-            self.DB_USER, self.DB_PASSWORD, self.DB_NAME, self.DB_PORT)
+        self.dsn = 'user={} password={} dbname={} host=localhost port={}'\
+            .format(self.DB_USER, self.DB_PASSWORD, self.DB_NAME, self.DB_PORT)
         try:
-            self.pg_client = PostgresClient(dsn=dsn, pool_size=10)
+            self.pg_client = PostgresClient(dsn=self.dsn,
+                                            pool_size=self.POOL_SIZE)
         except psycopg2.OperationalError as err:
             print('Check that postgres docker container is started. '
                   'Check README for more information')
@@ -65,6 +68,12 @@ def _drop_table(self):
     def tearDown(self):
         self._drop_table()
 
+    def test_create_with_wrong_pool_value(self):
+        with self.assertRaises(ValueError) as err:
+            pg_client = PostgresClient(dsn=self.dsn, pool_size=0)
+            self.assertIsNone(pg_client)
+            self.assertIn('Wrong pool_size value', err)
+
     def test_cursor(self):
         with self.pg_client.cursor as cursor:
             cursor.execute('SELECT * FROM users')
@@ -98,10 +107,28 @@ def test_success_transaction(self):
         self.assertEqual(len(result_set), 101)
 
     def test_rollback_transaction(self):
-        # Insert null username must cause an error
-        with self.pg_client.cursor as transaction:
-            with self.assertRaises(psycopg2.DatabaseError) as err:
+        # Inserting null username value must raise an error
+        with self.assertRaises(psycopg2.DatabaseError) as err:
+            with self.pg_client.cursor as transaction:
                 transaction.execute(
-                    "INSERT INTO {} (username) VALUES (%s)".format(self.TABLE_NAME),
+                    "INSERT INTO {} (username) VALUES (%s)".format(
+                        self.TABLE_NAME),
                     (None, ))
-            self.assertIn('null value in column', err.exception.message)
+                print('abc')
+        self.assertIn('null value in column', err.exception.message)
+        print('transaction finished')
+
+    def test_connection_pool_overflow(self):
+        # Consume all connection to check overflow case
+        connections = []
+        for i in range(self.POOL_SIZE):
+            connections.append(self.pg_client.acquire_conn())
+
+        with self.assertRaises(PoolError) as err:
+            with self.pg_client.cursor as cursor:
+                self.assertIsNone(cursor)
+                self.assertIn('connection pool exhausted', err)
+
+        # Release all connections back to pool
+        for conn in connections:
+            self.pg_client.release_conn(conn)