Add basic test for downgrades between hotfix versions

Author: mfussenegger

tests/bwc/test_hotfix_downgrades.py

@@ -0,0 +1,28 @@
+
+import unittest
+from crate.qa.tests import NodeProvider, wait_for_active_shards
+from crate.client import connect
+
+
+class HotfixDowngradeTest(NodeProvider, unittest.TestCase):
+
+    def test_latest_testing_can_be_downgraded_within_hotfix_versions(self):
+        cluster = self._new_cluster('latest-testing', 2)
+        cluster.start()
+        node = cluster.node()
+        with connect(node.http_url, error_trace=True) as conn:
+            c = conn.cursor()
+            c.execute('CREATE TABLE tbl (x int)')
+            c.execute('INSERT INTO tbl (x) values (?)', (10,))
+        major, feature, hotfix = node.version
+        for i in range(hotfix, 0, -1):
+            new_version = (major, feature, i)
+            with self.subTest(version=new_version):
+                node = self.upgrade_node(node, '.'.join(map(str, new_version)))
+
+                with connect(node.http_url, error_trace=True) as conn:
+                    c = conn.cursor()
+                    wait_for_active_shards(c)
+                    c.execute('SELECT x FROM tbl')
+                    xs = [row[0] for row in c.fetchall()]
+                    self.assertEqual(xs, [10])