SERVER-31392: Test changeStreams when an unsharded collection becomes sharded

2 files changed, 85 insertions, 0 deletions

diff --git a/buildscripts/resmokeconfig/suites/sharding_last_stable_mongos_and_mixed_shards.yml b/buildscripts/resmokeconfig/suites/sharding_last_stable_mongos_and_mixed_shards.yml
index b34190b9ce0..836b9c2ccf2 100644
--- a/buildscripts/resmokeconfig/suites/sharding_last_stable_mongos_and_mixed_shards.yml
+++ b/buildscripts/resmokeconfig/suites/sharding_last_stable_mongos_and_mixed_shards.yml
@@ -39,6 +39,7 @@ selector:
   - jstests/sharding/change_stream_invalidation.js
   - jstests/sharding/change_stream_remove_shard.js
   - jstests/sharding/change_streams.js
+  - jstests/sharding/change_streams_unsharded_becomes_sharded.js
   - jstests/sharding/close_cursor_on_chunk_migration_to_new_shards.js
   - jstests/sharding/close_cursor_on_chunk_migration_to_new_shards.js
   - jstests/sharding/enable_sharding_basic.js
diff --git a/jstests/sharding/change_streams_unsharded_becomes_sharded.js b/jstests/sharding/change_streams_unsharded_becomes_sharded.js
new file mode 100644
index 00000000000..07fd882cc5f
--- /dev/null
+++ b/jstests/sharding/change_streams_unsharded_becomes_sharded.js
@@ -0,0 +1,84 @@
+// Tests the behavior of change streams on a collection that was initially unsharded but then
+// becomes sharded.
+(function() {
+    "use strict";
+
+    load('jstests/libs/change_stream_util.js');  // For ChangeStreamTest.
+
+    // For supportsMajorityReadConcern().
+    load("jstests/multiVersion/libs/causal_consistency_helpers.js");
+
+    if (!supportsMajorityReadConcern()) {
+        jsTestLog("Skipping test since storage engine doesn't support majority read concern.");
+        return;
+    }
+
+    const testName = "change_streams_unsharded_becomes_sharded";
+    const st = new ShardingTest({
+        shards: 2,
+        mongos: 1,
+        rs: {
+            nodes: 1,
+            enableMajorityReadConcern: '',
+            // Use a higher frequency for periodic noops to speed up the test.
+            setParameter: {periodicNoopIntervalSecs: 1, writePeriodicNoops: true}
+        }
+    });
+
+    const mongosDB = st.s0.getDB(testName);
+    const mongosColl = mongosDB[testName];
+
+    mongosDB.createCollection(testName);
+
+    st.ensurePrimaryShard(mongosDB.getName(), st.rs0.getURL());
+
+    // Establish a change stream cursor on the unsharded collection.
+    let cst = new ChangeStreamTest(mongosDB);
+    let cursor =
+        cst.startWatchingChanges({pipeline: [{$changeStream: {}}], collection: mongosColl});
+    assert.eq(0, cursor.firstBatch.length, "Cursor had changes: " + tojson(cursor));
+
+    // Enable sharding on the previously unsharded collection.
+    assert.commandWorked(mongosDB.adminCommand({enableSharding: mongosDB.getName()}));
+
+    // Shard the collection on _id.
+    assert.commandWorked(
+        mongosDB.adminCommand({shardCollection: mongosColl.getFullName(), key: {_id: 1}}));
+
+    // Split the collection into 2 chunks: [MinKey, 0), [0, MaxKey).
+    assert.commandWorked(
+        mongosDB.adminCommand({split: mongosColl.getFullName(), middle: {_id: 0}}));
+
+    // Verify that the cursor is still valid and picks up the inserted document.
+    assert.writeOK(mongosColl.insert({_id: 1}));
+    cst.assertNextChangesEqual({
+        cursor: cursor,
+        expectedChanges: [{
+            documentKey: {_id: 1},
+            fullDocument: {_id: 1},
+            ns: {db: mongosDB.getName(), coll: mongosColl.getName()},
+            operationType: "insert",
+        }]
+    });
+
+    // Move the [minKey, 0) chunk to shard1 and write a document to it.
+    assert.commandWorked(mongosDB.adminCommand({
+        moveChunk: mongosColl.getFullName(),
+        find: {_id: -1},
+        to: st.rs1.getURL(),
+        _waitForDelete: true
+    }));
+    assert.writeOK(mongosColl.insert({_id: -1}));
+
+    // Since a moveChunk was requested, the cursor results should indicate a retry is needed.
+    // TODO: SERVER-30834 this result will get swallowed and the change stream cursor should see
+    // the inserted document.
+    cst.assertNextChangesEqual({
+        cursor: cursor,
+        expectedChanges: [{
+            operationType: "retryNeeded",
+        }]
+    });
+
+    st.stop();
+})();