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diff --git a/js/src/tests/test262/built-ins/FinalizationRegistry/prototype/cleanupSome/cleanup-prevented-with-unregister.js b/js/src/tests/test262/built-ins/FinalizationRegistry/prototype/cleanupSome/cleanup-prevented-with-unregister.js
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+++ b/js/src/tests/test262/built-ins/FinalizationRegistry/prototype/cleanupSome/cleanup-prevented-with-unregister.js
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+// |reftest| skip-if(!this.hasOwnProperty('FinalizationRegistry')) async -- FinalizationRegistry is not enabled unconditionally
+// Copyright (C) 2019 Leo Balter. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-finalization-registry.prototype.cleanupSome
+description: Cleanup might be prevented with an unregister usage
+info: |
+  FinalizationRegistry.prototype.cleanupSome ( [ callback ] )
+
+  1. Let finalizationRegistry be the this value.
+  2. If Type(finalizationRegistry) is not Object, throw a TypeError exception.
+  3. If finalizationRegistry does not have a [[Cells]] internal slot, throw a TypeError exception.
+  4. If callback is not undefined and IsCallable(callback) is false, throw a TypeError exception.
+  5. Perform ? CleanupFinalizationRegistry(finalizationRegistry, callback).
+  6. Return undefined.
+
+  FinalizationRegistry.prototype.unregister ( unregisterToken )
+
+  1. Let removed be false.
+  2. For each Record { [[Target]], [[Holdings]], [[UnregisterToken]] } cell that is an element of finalizationRegistry.[[Cells]], do
+    a. If SameValue(cell.[[UnregisterToken]], unregisterToken) is true, then
+      i. Remove cell from finalizationRegistry.[[Cells]].
+      ii. Set removed to true.
+  3. Return removed.
+features: [FinalizationRegistry.prototype.cleanupSome, FinalizationRegistry, host-gc-required]
+includes: [async-gc.js]
+flags: [async, non-deterministic]
+---*/
+
+var token = {};
+var finalizationRegistry = new FinalizationRegistry(function() {});
+
+function emptyCells() {
+  var target = {};
+  finalizationRegistry.register(target, 'target!', token);
+
+  var prom = asyncGC(target);
+  target = null;
+
+  return prom;
+}
+
+emptyCells().then(function() {
+  var called = 0;
+
+  var res = finalizationRegistry.unregister(token);
+  assert.sameValue(res, true, 'unregister target before iterating over it in cleanup');
+
+  finalizationRegistry.cleanupSome(function cb(holding) {
+    called += 1;
+  });
+
+  assert.sameValue(called, 0, 'callback was not called');
+}).then($DONE, resolveAsyncGC);