Add m-esr52 at 52.6.0

1 files changed, 32 insertions, 0 deletions

diff --git a/js/src/jit-test/tests/proxy/testDirectProxySetFailure.js b/js/src/jit-test/tests/proxy/testDirectProxySetFailure.js
new file mode 100644
index 000000000..3646fc69b
--- /dev/null
+++ b/js/src/jit-test/tests/proxy/testDirectProxySetFailure.js
@@ -0,0 +1,32 @@
+// Test handling of false return from a handler.set() hook.
+
+load(libdir + "asserts.js");
+
+var obj = {x: 1};
+var p = new Proxy(obj, {
+    set(target, key, value, receiver) { return false; }
+});
+
+// Failing to set a property is a no-op in non-strict code.
+assertEq(p.x = 2, 2);
+assertEq(obj.x, 1);
+
+// It's a TypeError in strict mode code.
+assertThrowsInstanceOf(() => { "use strict"; p.x = 2; }, TypeError);
+assertEq(obj.x, 1);
+
+// Even if the value doesn't change.
+assertThrowsInstanceOf(() => { "use strict"; p.x = 1; }, TypeError);
+assertEq(obj.x, 1);
+
+// Even if the target property doesn't already exist.
+assertThrowsInstanceOf(() => { "use strict"; p.z = 1; }, TypeError);
+assertEq("z" in obj, false);
+
+// [].sort() mutates its operand only by doing strict [[Set]] calls.
+var arr = ["not", "already", "in", "order"];
+var p2 = new Proxy(arr, {
+    set(target, key, value, receiver) { return false; }
+});
+assertThrowsInstanceOf(() => p2.sort(), TypeError);
+assertDeepEq(arr, ["not", "already", "in", "order"]);