1 files changed, 76 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/FinalizationRegistry/prototype/register/return-undefined-register-symbol.js b/js/src/tests/test262/built-ins/FinalizationRegistry/prototype/register/return-undefined-register-symbol.js
new file mode 100644
index 0000000000..8c8a944429
--- /dev/null
+++ b/js/src/tests/test262/built-ins/FinalizationRegistry/prototype/register/return-undefined-register-symbol.js
@@ -0,0 +1,76 @@
+// |reftest| shell-option(--enable-symbols-as-weakmap-keys) skip-if(release_or_beta||!this.hasOwnProperty('FinalizationRegistry')||!xulRuntime.shell) -- symbols-as-weakmap-keys is not released yet, FinalizationRegistry is not enabled unconditionally, requires shell-options
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-finalization-registry.prototype.register
+description: Return undefined after registering a Symbol
+info: |
+  FinalizationRegistry.prototype.register ( _target_ , _heldValue_ [, _unregisterToken_ ] )
+  8. Return *undefined*.
+features: [FinalizationRegistry, Symbol, symbols-as-weakmap-keys]
+---*/
+
+var fn = function() {};
+var reg = new FinalizationRegistry(fn);
+
+var target = Symbol('a description');
+assert.sameValue(reg.register(target), undefined, 'Register a regular symbol');
+assert.sameValue(reg.register(target), undefined, 'Register the same symbol again');
+assert.sameValue(reg.register(target), undefined, 'Register the same symbol a third time');
+
+assert.sameValue(
+  reg.register(Symbol('a description')),
+  undefined,
+  'Register another symbol with the same description'
+);
+assert.sameValue(
+  reg.register(Symbol('a different description')),
+  undefined,
+  'Register another symbol with another description'
+);
+
+assert.sameValue(
+  reg.register(target, undefined, Symbol('unregister token')),
+  undefined,
+  'Register a regular symbol with a symbol unregister token'
+);
+assert.sameValue(
+  reg.register(target, undefined, target),
+  undefined,
+  'Register a regular symbol with itself as the unregister token'
+);
+
+assert.sameValue(
+  reg.register(target, undefined, undefined),
+  undefined,
+  'Register a regular symbol with explicit undefined unregister token'
+);
+
+assert.sameValue(reg.register(Symbol.hasInstance), undefined, 'Register a well-known symbol');
+assert.sameValue(reg.register(Symbol.hasInstance), undefined, 'Register the same well-known symbol again');
+assert.sameValue(reg.register(Symbol.hasInstance), undefined, 'Register the same well-known symbol a third time');
+
+assert.sameValue(
+  reg.register(target, undefined, Symbol.hasInstance),
+  undefined,
+  'Register a regular symbol with a well-known symbol unregister token'
+);
+assert.sameValue(
+  reg.register(Symbol.hasInstance, undefined, Symbol.iterator),
+  undefined,
+  'Register a well-known symbol with a different well-known symbol as unregister token'
+);
+assert.sameValue(
+  reg.register(Symbol.hasInstance, undefined, Symbol.hasInstance),
+  undefined,
+  'Register a well-known symbol with itself as the unregister token'
+);
+
+assert.sameValue(
+  reg.register(Symbol.hasInstance, undefined, undefined),
+  undefined,
+  'Register a well-known symbol with explicit undefined unregister token'
+);
+
+reportCompare(0, 0);