fix(db_api): ensure DDL statements are being executed (#290)

* fix(db_api): DDLs are not executed immediately in autocommit mode

* fix DDLs committing, add system tests

* erase insert statement

Author: Ilya Gurov

google/cloud/spanner_dbapi/connection.py

@@ -243,7 +243,10 @@ def commit(self):
         """
         if self._autocommit:
             warnings.warn(AUTOCOMMIT_MODE_WARNING, UserWarning, stacklevel=2)
-        elif self.inside_transaction:
+            return
+
+        self.run_prior_DDL_statements()
+        if self.inside_transaction:
             try:
                 self._transaction.commit()
                 self._release_session()

google/cloud/spanner_dbapi/cursor.py

@@ -178,6 +178,8 @@ def execute(self, sql, args=None):
                     ddl = ddl.strip()
                     if ddl:
                         self.connection._ddl_statements.append(ddl)
+                if self.connection.autocommit:
+                    self.connection.run_prior_DDL_statements()
                 return
 
             # For every other operation, we've got to ensure that

tests/system/test_system_dbapi.py

@@ -378,6 +378,54 @@ def test_execute_many(self):
         self.assertEqual(res[0], 1)
         conn.close()
 
+    def test_DDL_autocommit(self):
+        """Check that DDLs in autocommit mode are immediately executed."""
+        conn = Connection(Config.INSTANCE, self._db)
+        conn.autocommit = True
+
+        cur = conn.cursor()
+        cur.execute(
+            """
+            CREATE TABLE Singers (
+                SingerId     INT64 NOT NULL,
+                Name    STRING(1024),
+            ) PRIMARY KEY (SingerId)
+        """
+        )
+        conn.close()
+
+        # if previous DDL wasn't committed, the next DROP TABLE
+        # statement will fail with a ProgrammingError
+        conn = Connection(Config.INSTANCE, self._db)
+        cur = conn.cursor()
+
+        cur.execute("DROP TABLE Singers")
+        conn.commit()
+
+    def test_DDL_commit(self):
+        """Check that DDLs in commit mode are executed on calling `commit()`."""
+        conn = Connection(Config.INSTANCE, self._db)
+        cur = conn.cursor()
+
+        cur.execute(
+            """
+        CREATE TABLE Singers (
+            SingerId     INT64 NOT NULL,
+            Name    STRING(1024),
+        ) PRIMARY KEY (SingerId)
+        """
+        )
+        conn.commit()
+        conn.close()
+
+        # if previous DDL wasn't committed, the next DROP TABLE
+        # statement will fail with a ProgrammingError
+        conn = Connection(Config.INSTANCE, self._db)
+        cur = conn.cursor()
+
+        cur.execute("DROP TABLE Singers")
+        conn.commit()
+
 
 def clear_table(transaction):
     """Clear the test table."""