SERVER-27125 Arbiters in PV1 vote no if they can see a healthy primary of equal or greater priority to the candidate

1 files changed, 58 insertions, 0 deletions

diff --git a/jstests/replsets/no_flapping_during_network_partition.js b/jstests/replsets/no_flapping_during_network_partition.js
new file mode 100644
index 00000000000..5a289b2afdd
--- /dev/null
+++ b/jstests/replsets/no_flapping_during_network_partition.js
@@ -0,0 +1,58 @@
+/*
+ * Test that arbiters vote no in elections if they can see a healthy primary of equal or greater
+ * priority to the candidate, preventing flapping during certain kinds of network partitions.
+ *
+ * 1.  Initiate a 3-node replica set with one arbiter (PSA) and a higher priority primary.
+ * 2.  Create a network partition between the primary and secondary.
+ * 3.  Wait long enough for the secondary to call for an election.
+ * 4.  Verify the primary and secondary did not change.
+ * 5.  Heal the partition.
+ * 6.  Verify the primary and secondary did not change and are in the initial term.
+ */
+
+(function() {
+    "use strict";
+
+    load("jstests/libs/check_log.js");
+
+    var name = "no_flapping_during_network_partition";
+
+    var replTest = new ReplSetTest({name: name, nodes: 3, useBridge: true});
+    var nodes = replTest.startSet();
+    var config = replTest.getReplSetConfig();
+    config.members[0].priority = 5;
+    config.members[2].arbiterOnly = true;
+    config.settings = {electionTimeoutMillis: 2000};
+    replTest.initiate(config);
+
+    function getTerm(node) {
+        return node.adminCommand({replSetGetStatus: 1}).term;
+    }
+
+    replTest.waitForState(nodes[0], ReplSetTest.State.PRIMARY);
+
+    var primary = replTest.getPrimary();
+    var secondary = replTest.getSecondary();
+    var initialTerm = getTerm(primary);
+
+    jsTestLog("Create a network partition between the primary and secondary.");
+    primary.disconnect(secondary);
+
+    jsTestLog("Wait long enough for the secondary to call for an election.");
+    checkLog.contains(secondary, "can see a healthy primary of equal or greater priority");
+
+    jsTestLog("Verify the primary and secondary do not change during the partition.");
+    assert.eq(primary, replTest.getPrimary());
+    assert.eq(secondary, replTest.getSecondary());
+
+    jsTestLog("Heal the partition.");
+    primary.reconnect(secondary);
+
+    jsTestLog("Verify the primary and secondary did not change and are in the initial term.");
+    assert.eq(primary, replTest.getPrimary());
+    assert.eq(secondary, replTest.getSecondary());
+    assert.eq(initialTerm, getTerm(primary));
+    assert.eq(initialTerm, getTerm(secondary));
+
+    replTest.stopSet();
+})();