SERVER-43043 Test applyOps on missing nested fields

3 files changed, 20 insertions, 5 deletions

diff --git a/src/mongo/db/repl/idempotency_test.cpp b/src/mongo/db/repl/idempotency_test.cpp
index e76599bc86a..96143015561 100644
--- a/src/mongo/db/repl/idempotency_test.cpp
+++ b/src/mongo/db/repl/idempotency_test.cpp
@@ -197,6 +197,21 @@ TEST_F(RandomizedIdempotencyTest, CheckUpdateSequencesAreIdempotent) {
     runIdempotencyTestCase();
 }
 
+TEST_F(IdempotencyTest, UpdateTwoFields) {
+    ASSERT_OK(
+        ReplicationCoordinator::get(_opCtx.get())->setFollowerMode(MemberState::RS_RECOVERING));
+
+    ASSERT_OK(runOpInitialSync(createCollection(kUuid)));
+    ASSERT_OK(runOpInitialSync(insert(fromjson("{_id: 1, y: [0]}"))));
+
+    auto updateOp1 = update(1, fromjson("{$set: {x: 1}}"));
+    auto updateOp2 = update(1, fromjson("{$set: {x: 2, 'y.0': 2}}"));
+    auto updateOp3 = update(1, fromjson("{$set: {y: 3}}"));
+
+    auto ops = {updateOp1, updateOp2, updateOp3};
+    testOpsAreIdempotent(ops);
+}
+
 }  // namespace
 }  // namespace repl
 }  // namespace mongo
diff --git a/src/mongo/db/repl/initial_syncer.cpp b/src/mongo/db/repl/initial_syncer.cpp
index c967983377e..8d3fdfec25a 100644
--- a/src/mongo/db/repl/initial_syncer.cpp
+++ b/src/mongo/db/repl/initial_syncer.cpp
@@ -94,7 +94,7 @@ MONGO_FAIL_POINT_DEFINE(initialSyncHangBeforeCreatingOplog);
 // Failpoint which stops the applier.
 MONGO_FAIL_POINT_DEFINE(rsSyncApplyStop);
 
-// Failpoint which causes the initial sync function to hang afte cloning all databases.
+// Failpoint which causes the initial sync function to hang after cloning all databases.
 MONGO_FAIL_POINT_DEFINE(initialSyncHangAfterDataCloning);
 
 // Failpoint which skips clearing _initialSyncState after a successful initial sync attempt.
diff --git a/src/mongo/db/update/modifier_node.cpp b/src/mongo/db/update/modifier_node.cpp
index dd0341255a3..2ea03766cf5 100644
--- a/src/mongo/db/update/modifier_node.cpp
+++ b/src/mongo/db/update/modifier_node.cpp
@@ -222,10 +222,10 @@ UpdateExecutor::ApplyResult ModifierNode::applyToNonexistentElement(
         auto statusWithFirstCreatedElem = pathsupport::createPathAt(
             *(updateNodeApplyParams.pathToCreate), 0, applyParams.element, newElement);
         if (!statusWithFirstCreatedElem.isOK()) {
-            // $set operaions on non-viable paths are ignored when the update came from replication.
-            // We do not error because idempotency requires that any other update modifiers must
-            // still be applied. For example, consider applying the following updates twice to an
-            // initially empty document:
+            // $set operations on non-viable paths are ignored when the update came from
+            // replication. We do not error because idempotency requires that any other update
+            // modifiers must still be applied. For example, consider applying the following updates
+            // twice to an initially empty document:
             // {$set: {c: 0}}
             // {$set: {'a.b': 0, c: 1}}
             // {$set: {a: 0}}