1 files changed, 48 insertions, 0 deletions
diff --git a/jstests/noPassthrough/merge_on_secondary.js b/jstests/noPassthrough/merge_on_secondary.js
new file mode 100644
index 00000000000..94ecd8cc232
--- /dev/null
+++ b/jstests/noPassthrough/merge_on_secondary.js
@@ -0,0 +1,48 @@
+/**
+ * Tests the behavior of $merge being run on a secondary.
+ *
+ * @tags: [assumes_unsharded_collection, requires_replication, requires_spawning_own_processes]
+ */
+(function() {
+"use strict";
+
+load("jstests/aggregation/extras/merge_helpers.js");  // For withEachMergeMode.
+
+let replTest = new ReplSetTest({nodes: 2});
+replTest.startSet();
+replTest.initiate();
+replTest.awaitReplication();
+
+let primary = replTest.getPrimary().getDB('test');
+let secondary = replTest.getSecondary().getDB('test');
+secondary.setSlaveOk(true);
+
+const collPrimary = primary.getCollection('coll');
+const collSecondary = secondary.getCollection('coll');
+const outColl = primary.getCollection('outColl');
+
+assert.commandWorked(collPrimary.insert({_id: 0, a: 1}, {writeConcern: {w: 2}}));
+assert.commandWorked(collPrimary.insert({_id: 1, a: 2}, {writeConcern: {w: 2}}));
+
+// Make sure the $merge succeeds without any duplicate keys.
+withEachMergeMode(({whenMatchedMode, whenNotMatchedMode}) => {
+    // Skip the combination of merge modes which will fail depending on the contents of the
+    // source and target collection, as this will cause the aggregation to fail.
+    if (whenMatchedMode == "fail" || whenNotMatchedMode == "fail") {
+        return;
+    }
+
+    collSecondary.aggregate([{
+        $merge: {
+            into: outColl.getName(),
+            whenMatched: whenMatchedMode,
+            whenNotMatched: whenNotMatchedMode
+        }
+    }]);
+
+    assert.eq(whenNotMatchedMode == "discard" ? 0 : 2, outColl.find().itcount());
+    outColl.drop();
+});
+
+replTest.stopSet();
+})();
+\ No newline at end of file