Provide sensible errors when a closed session is used.

Author: srbaker

neo4j/v1/api.py

@@ -423,6 +423,11 @@ def __init__(self, data):
                 setattr(self, key, value)
 
 
+class SessionError(Exception):
+    """ Raised when an error occurs while using a session.
+    """
+
+
 class TransactionError(Exception):
     """ Raised when an error occurs while using a transaction.
     """

neo4j/v1/bolt.py

@@ -24,7 +24,7 @@
 from .api import GraphDatabase, Driver, Session, StatementResult, \
     READ_ACCESS, WRITE_ACCESS, \
     fix_statement, fix_parameters, \
-    CypherError, SessionExpired
+    CypherError, SessionExpired, SessionError
 from .routing import RoutingConnectionPool
 from .security import SecurityPlan
 from .summary import ResultSummary
@@ -131,6 +131,9 @@ def run(self, statement, parameters=None, **kwparameters):
         :return: Cypher result
         :rtype: :class:`.StatementResult`
         """
+        if not self.connection:
+            raise SessionError("This session is closed.")
+
         self.last_bookmark = None
 
         statement = fix_statement(statement)

test/test_session.py

@@ -25,7 +25,7 @@
 
 from neo4j.v1 import \
     GraphDatabase, basic_auth, READ_ACCESS, WRITE_ACCESS, \
-    CypherError, \
+    CypherError, SessionError, \
     Node, Relationship, Path
 from neo4j.v1.types import Record
 
@@ -673,3 +673,22 @@ def test_should_sync_after_rollback(self):
             buffer = result._records
             assert len(buffer) == 1
             assert buffer[0][0] == 1
+
+
+class SessionClosedTestCase(ServerTestCase):
+
+    def setUp(self):
+        self.driver = GraphDatabase.driver(BOLT_URI, auth=AUTH_TOKEN)
+        self.session = self.driver.session()
+        self.session.close()
+
+    def tearDown(self):
+        self.driver.close()
+
+    def test_errors_on_run(self):
+        with self.assertRaises(SessionError):
+            self.session.run("RETURN 1")
+
+    def test_errors_on_begin_transaction(self):
+        with self.assertRaises(SessionError):
+            self.session.begin_transaction()