1 files changed, 46 insertions, 0 deletions
diff --git a/jstests/sharding/query/metadata_removal.js b/jstests/sharding/query/metadata_removal.js
new file mode 100644
index 00000000000..7caba6433bc
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+++ b/jstests/sharding/query/metadata_removal.js
@@ -0,0 +1,46 @@
+// Ensure that metadata fields (and only metadata) are removed before documents are returned to
+// customers. As we can't insert documents with metadata, this test focuses on queries that might
+// inject metadata when communication results to mongos for merging. In addition, we want to ensure
+// that other fields beginning with a '$' are not modified before returning them to customers.
+// @tags: [
+//   requires_fcv_60
+// ]
+
+(function() {
+"use strict";
+
+function runTest(coll, keyword) {
+    const document = ({_id: 5, x: 1, $set: {$inc: {x: 5}}});
+    assert.commandWorked(coll.insert(document));
+
+    // Leaves $set intact without shard merging.
+    assert.eq([document], coll.find().hint({$natural: 1}).toArray());
+    assert.eq([document], coll.find().hint({_id: 1}).toArray());
+
+    // Leaves $set intact when shard merging on agg query.
+    const docWithY = ({_id: 5, x: 1, $set: {$inc: {x: 5}}, y: 1});
+    assert.eq([docWithY], coll.aggregate([{$addFields: {y: 1}}]).toArray());
+
+    // Leaves $set intact when shard merging on sort query.
+    assert.eq([document], coll.find().sort({_id: 1}).toArray());
+
+    // Leaves added fields intact when user adds $ prefixed field in an agg pipeline.
+    const docWithDollarY = ({_id: 5, x: 1, $set: {$inc: {x: 5}}, $y: 1});
+    assert.eq(
+        [docWithDollarY],
+        coll.aggregate(
+                [{$replaceWith: {$setField: {field: {$literal: "$y"}, input: "$$ROOT", value: 1}}}])
+            .toArray());
+}
+
+const st = new ShardingTest({shards: 2});
+try {
+    assert.commandWorked(st.s0.adminCommand({enableSharding: 'test'}));
+    st.ensurePrimaryShard('test', st.shard1.shardName);
+    assert.commandWorked(st.s0.adminCommand({shardCollection: 'test.coll', key: {x: 'hashed'}}));
+
+    runTest(st.getDB("test").coll);
+} finally {
+    st.stop();
+}
+})();