SERVER-21545 Correctly roll back updating collection options

(cherry picked from commit a4d29291cc3ee4d44970fc450e0a7124828394b2)

1 files changed, 23 insertions, 0 deletions

diff --git a/jstests/core/collmod_bad_spec.js b/jstests/core/collmod_bad_spec.js
new file mode 100644
index 00000000000..ccce81fd4b1
--- /dev/null
+++ b/jstests/core/collmod_bad_spec.js
@@ -0,0 +1,23 @@
+// This is a regression test for SERVER-21545.
+//
+// Tests that a collMod with a bad specification does not cause any changes, and does not crash the
+// server.
+(function() {
+    "use strict";
+
+    var collName = "collModBadSpec";
+    var coll = db.getCollection(collName);
+
+    coll.drop();
+    assert.commandWorked(db.createCollection(collName));
+
+    // Get the original collection options for the collection.
+    var originalResult = db.getCollectionInfos({name: collName});
+
+    // Issue an invalid command.
+    assert.commandFailed(coll.runCommand("collMod", {validationLevel: "off", unknownField: "x"}));
+
+    // Make sure the options are unchanged.
+    var newResult = db.getCollectionInfos({name: collName});
+    assert.eq(originalResult, newResult);
+})();