michael@0: // Setting a Map key to undefined, or a missing argument, isn't the same as deleting it.
michael@0: 
michael@0: var m = new Map;
michael@0: m.set(42, undefined);
michael@0: assertEq(m.has(42), true);
michael@0: assertEq(m.get(42), undefined);
michael@0: 
michael@0: m.set(42, "wrong");
michael@0: m.set(42);
michael@0: assertEq(m.has(42), true);
michael@0: assertEq(m.get(42), undefined);
michael@0: 
michael@0: m.set();
michael@0: assertEq(m.has(undefined), true);
michael@0: assertEq(m.get(undefined), undefined);