Add a new test for the Cursor.next extension

dbapi20.py

@@ -495,7 +495,7 @@ def test_fetchone(self):
             cur.execute('select name from %sbooze' % self.table_prefix)
             r = cur.fetchone()
             self.assertEqual(len(r),1,
-                'cursor.fetchone should have retrieved a single row'
+                'cursor.fetchone should have retrieved a row with one columns'
                 )
             self.assertEqual(r[0],'Victoria Bitter',
                 'cursor.fetchone retrieved incorrect data'
@@ -507,6 +507,50 @@ def test_fetchone(self):
         finally:
             con.close()
 
+    def test_next(self):
+        # https://www.python.org/dev/peps/pep-0249/#next
+        con = self._connect()
+        try:
+            cur = con.cursor()
+            if not hasattr(cur,'next'):
+                return
+
+            # cursor.next should raise an Error if called before
+            # executing a select-type query
+            self.assertRaises(self.driver.Error,cur.next)
+
+            # cursor.next should raise an Error if called after
+            # executing a query that cannnot return rows
+            self.executeDDL1(cur)
+            self.assertRaises(self.driver.Error,cur.next)
+
+            # cursor.next should return None if a query retrieves '
+            # no rows
+            cur.execute('select name from %sbooze' % self.table_prefix)
+            self.assertRaises(StopIteration,cur.next)
+            _failUnless(self,cur.rowcount in (-1,0))
+
+            # cursor.next should raise an Error if called after
+            # executing a query that cannnot return rows
+            cur.execute("%s into %sbooze values ('Victoria Bitter')" % (
+                self.insert, self.table_prefix
+                ))
+            self.assertRaises(self.driver.Error,cur.next)
+
+            cur.execute('select name from %sbooze' % self.table_prefix)
+            r = cur.next()
+            self.assertEqual(len(r),1,
+                'cursor.next should have retrieved a row with one column'
+                )
+            self.assertEqual(r[0],'Victoria Bitter',
+                'cursor.next retrieved incorrect data'
+                )
+            # cursor.next should raise StopIteration if no more rows available
+            self.assertRaises(StopIteration,cur.next)
+            _failUnless(self,cur.rowcount in (-1,1))
+        finally:
+            con.close()
+
     samples = [
         'Carlton Cold',
         'Carlton Draft',