Support structured cloning of ES'15 Map and Set

LayoutTests/fast/js/structured-clone.html

Index: LayoutTests/fast/js/structured-clone.html
diff --git a/LayoutTests/fast/js/structured-clone.html b/LayoutTests/fast/js/structured-clone.html
index 6cd9c365878d5340ae30ced8ce4297c7a39f3dde..dfa7740ac8e9e1f885df5ff5008a65e56927c499 100644
--- a/LayoutTests/fast/js/structured-clone.html
+++ b/LayoutTests/fast/js/structured-clone.html
@@ -119,4 +119,38 @@ promise_test(function() {
     });
 }, 'Verify: "Add a new property..." (dense arrays)');
 
+promise_test(function() {
+    var orig = {
+        emptySet: new Set,
+        set: new Set([1, 2, 3]),
+        emptyMap: new Map,
+        map: new Map([[1, 2], [3, 4]]),
+    };
+    return structuredClone(orig).then(function(clone) {
+        assert_true(clone.emptySet instanceof Set, 'Clone should be a Set');
+        assert_true(clone.emptyMap instanceof Map, 'Clone should be a Map');
+        assert_true(clone.set instanceof Set, 'Clone should be a Set');
+        assert_true(clone.map instanceof Map, 'Clone should be a Map');
+        assert_equals(clone.set.size, orig.set.size, 'Clone should be the same size');

[jsbell, 2015/06/24 20:30:43]

Should probably have asserts about emptySet/emptyMap sizes too.

[adamk, 2015/06/24 21:13:32]

Done.

+        assert_equals(clone.map.size, orig.map.size, 'Clone should be the same size');
+        assert_true(clone.set.has(1) && clone.set.has(2) && clone.set.has(3), 'Cloned set should have the same keys');
+        assert_true(clone.map.get(1) == 2 && clone.map.get(3) == 4, 'Cloned map should have the same keys and values');
+    });
+}, 'Verify: "Maps and Sets are cloned..."');

[jsbell, 2015/06/24 20:30:42]

The 'Verify: "xxxx..."' phrasing in tests above is quoting from the HTML spec
itself. I don't think this is a quote?

[adamk, 2015/06/24 21:13:31]

I've removed the quotes and the ellipses. Should I actually move these tests to
a different file?

[jsbell, 2015/06/24 21:37:10]

I think this file is fine.

+
+promise_test(function() {
+    var set = new Set;
+    set.add(set);
+    var map = new Map;
+    map.set(map, map);
+    var orig = { map: map, set: set };
+    return structuredClone(orig).then(function(clone) {
+        assert_true(clone.set instanceof Set, 'Clone should be a Set');
+        assert_true(clone.map instanceof Map, 'Clone should be a Map');
+        assert_true(clone.set === Array.from(clone.set)[0], 'Recursive sets should maintain identity');

[jsbell, 2015/06/24 20:30:43]

Use assert_equals() for these (it does 'same value' equivalent to Object.is)

[adamk, 2015/06/24 21:13:31]

Done.

+        assert_true(clone.map === Array.from(clone.map)[0][0], 'Recursive maps should maintain identity');
+        assert_true(clone.map === Array.from(clone.map)[0][1], 'Recursive maps should maintain identity');
+    });
+}, 'Verify: "Maps and Sets can contain themselves..."');

[jsbell, 2015/06/24 20:30:43]

Ditto.

[adamk, 2015/06/24 21:13:32]

Done.

+

[jsbell, 2015/06/24 20:30:42]

Can you add a test where a member of the map/set has a getter that mutates the
map/set itself?

[adamk, 2015/06/24 21:13:32]

Done. Should we file a bug for this?

[jsbell, 2015/06/24 21:37:10]

Against HTML? Probably.

One more edge case we should test: Map/Set containing a key and/or value that is
not cloneable (e.g. an Error)

[adamk, 2015/06/24 22:50:31]

Non-cloneability tests added.

[adamk, 2015/06/24 23:48:53]

Filed https://www.w3.org/Bugs/Public/show_bug.cgi?id=28849

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