Add systets for multiuse snapshots w/ read_timestamp / exact_staleness.

Author: tseaver

spanner/tests/system/test_system.py

@@ -589,6 +589,43 @@ def test_multiuse_snapshot_read_isolation_strong(self):
 after=list(strong.read(self.TABLE, self.COLUMNS, self.ALL))
 self._check_row_data(after, all_data_rows)
 
+deftest_multiuse_snapshot_read_isolation_read_timestamp(self):
+ROW_COUNT=40
+session, committed=self._set_up_table(ROW_COUNT)
+all_data_rows=list(self._row_data(ROW_COUNT))
+read_ts=session.snapshot(read_timestamp=committed, multi_use=True)
+
+before=list(read_ts.read(self.TABLE, self.COLUMNS, self.ALL))
+self._check_row_data(before, all_data_rows)
+
+withself._db.batch() asbatch:
+batch.delete(self.TABLE, self.ALL)
+
+after=list(read_ts.read(self.TABLE, self.COLUMNS, self.ALL))
+self._check_row_data(after, all_data_rows)
+
+deftest_multiuse_snapshot_read_isolation_exact_staleness(self):
+importtime
+fromdatetimeimporttimedelta
+ROW_COUNT=40
+
+session, committed=self._set_up_table(ROW_COUNT)
+all_data_rows=list(self._row_data(ROW_COUNT))
+
+time.sleep(1)
+delta=timedelta(microseconds=1000)
+
+exact=session.snapshot(exact_staleness=delta, multi_use=True)
+
+before=list(exact.read(self.TABLE, self.COLUMNS, self.ALL))
+self._check_row_data(before, all_data_rows)
+
+withself._db.batch() asbatch:
+batch.delete(self.TABLE, self.ALL)
+
+after=list(exact.read(self.TABLE, self.COLUMNS, self.ALL))
+self._check_row_data(after, all_data_rows)
+
 deftest_read_w_manual_consume(self):
 ROW_COUNT=4000
 session, committed=self._set_up_table(ROW_COUNT)