SERVER-63437 Expose all events on 'system.resharding' collections when 'showSystemEvents' is true

Co-authored-by: Arun Banala <arun.banala@mongodb.com>

1 files changed, 142 insertions, 0 deletions

diff --git a/jstests/change_streams/show_resharding_system_events.js b/jstests/change_streams/show_resharding_system_events.js
new file mode 100644
index 00000000000..8463102419a
--- /dev/null
+++ b/jstests/change_streams/show_resharding_system_events.js
@@ -0,0 +1,142 @@
+/**
+ * Tests the behavior of change streams on a system.resharding.* namespace in the presence of
+ * 'showSystemEvents' flag. This is a separate test from 'show_system_events.js' because it can only
+ * operate in a sharded cluster.
+ *
+ * @tags: [
+ *  requires_fcv_61,
+ *  featureFlagChangeStreamsVisibility,
+ *  featureFlagChangeStreamsFurtherEnrichedEvents,
+ *  requires_sharding,
+ *  uses_change_streams,
+ *  change_stream_does_not_expect_txns,
+ *  assumes_unsharded_collection,
+ *  assumes_read_preference_unchanged,
+ * ]
+ */
+(function() {
+"use strict";
+
+load('jstests/libs/change_stream_util.js');  // For 'assertChangeStreamEventEq'.
+
+// Create a single-shard cluster for this test.
+const st = new ShardingTest({
+    shards: 1,
+    rs: {nodes: 1, setParameter: {writePeriodicNoops: true, periodicNoopIntervalSecs: 1}}
+});
+
+const testDB = st.s.getDB(jsTestName());
+const testColl = testDB[jsTestName()];
+
+// Shard the collection based on '_id'.
+st.shardColl(testColl, {_id: 1}, false);
+
+// Build an index on the collection to support the resharding operation.
+assert.commandWorked(testColl.createIndex({a: 1}));
+
+// Insert some documents that will be resharded.
+assert.commandWorked(testColl.insert({_id: 0, a: 0}));
+assert.commandWorked(testColl.insert({_id: 1, a: 1}));
+
+// Helper function to retrieve the UUID of the specified collection.
+function getCollectionUuid(coll) {
+    const collInfo = testDB.getCollectionInfos({name: coll.getName()})[0];
+    return collInfo.info.uuid;
+}
+
+// Obtain a resume token indicating the start point for the test.
+const startPoint = testDB.watch().getResumeToken();
+
+// Get the UUID of the collection before resharding.
+const oldUUID = getCollectionUuid(testColl);
+
+// Reshard the collection.
+assert.commandWorked(st.s.adminCommand({
+    reshardCollection: testColl.getFullName(),
+    key: {a: 1},
+}));
+
+// Get the UUID of the collection after resharding.
+const newUUID = getCollectionUuid(testColl);
+
+// Write one more sentinel document into the collection.
+assert.commandWorked(testColl.insert({_id: 2, a: 2}));
+
+// Now confirm the sequence of events that we expect to see in the change stream.
+const reshardingCollName = `system.resharding.${oldUUID.toString().match(/\"([^\"]+)\"/)[1]}`;
+const reshardingNs = {
+    db: testDB.getName(),
+    coll: reshardingCollName
+};
+const origNs = {
+    db: testDB.getName(),
+    coll: testColl.getName()
+};
+const expectedReshardingEvents = [
+    {ns: reshardingNs, collectionUUID: newUUID, operationType: "create"},
+    {
+        ns: reshardingNs,
+        collectionUUID: newUUID,
+        operationType: "createIndexes",
+        operationDescription: {indexes: [{v: 2, key: {a: 1}, name: "a_1"}]}
+    },
+    {
+        ns: reshardingNs,
+        collectionUUID: newUUID,
+        operationType: "shardCollection",
+        operationDescription: {shardKey: {a: 1}}
+    },
+    {
+        ns: reshardingNs,
+        collectionUUID: newUUID,
+        operationType: "insert",
+        fullDocument: {_id: 0, a: 0},
+        documentKey: {a: 0, _id: 0}
+    },
+    {
+        ns: reshardingNs,
+        collectionUUID: newUUID,
+        operationType: "insert",
+        fullDocument: {_id: 1, a: 1},
+        documentKey: {a: 1, _id: 1}
+    },
+    {
+        ns: origNs,
+        collectionUUID: oldUUID,
+        operationType: "reshardCollection",
+        operationDescription:
+            {reshardUUID: newUUID, shardKey: {a: 1}, oldShardKey: {_id: 1}, unique: false}
+    },
+    {
+        ns: origNs,
+        collectionUUID: newUUID,
+        operationType: "insert",
+        fullDocument: {_id: 2, a: 2},
+        documentKey: {a: 2, _id: 2}
+    },
+];
+
+// Helper to confirm the sequence of events observed in the change stream.
+function assertChangeStreamEventSequence(csConfig, expectedEvents) {
+    // Open a change stream on the test DB using the given configuration.
+    const finalConfig =
+        Object.assign({resumeAfter: startPoint, showExpandedEvents: true}, csConfig);
+    const csCursor = testDB.watch([], finalConfig);
+
+    // Confirm that we see the expected sequence of events.
+    expectedEvents.forEach((expectedEvent) => {
+        assert.soon(() => csCursor.hasNext());
+        assertChangeStreamEventEq(csCursor.next(), expectedEvent);
+    });
+}
+
+// With showSystemEvents set to true, we expect to see the full sequence of events.
+assertChangeStreamEventSequence({showSystemEvents: true}, expectedReshardingEvents);
+
+// With showSystemEvents set to false, we expect to only see events on the original namespace.
+const nonSystemEvents =
+    expectedReshardingEvents.filter((event) => (event.ns.coll === testColl.getName()));
+assertChangeStreamEventSequence({showSystemEvents: false}, nonSystemEvents);
+
+st.stop();
+}());
\ No newline at end of file