src/third_party/mozjs-45/js/src/jit-test/tests/collections/WeakMap-constructor-1.js

// The WeakMap constructor creates an empty WeakMap by default.

load(libdir + "asserts.js");

new WeakMap();
new WeakMap(undefined);
new WeakMap(null);

assertThrowsInstanceOf(() => WeakMap(), TypeError);
assertThrowsInstanceOf(() => WeakMap(undefined), TypeError);
assertThrowsInstanceOf(() => WeakMap(null), TypeError);