Add m-esr52 at 52.6.0

1 files changed, 33 insertions, 0 deletions

diff --git a/js/src/tests/ecma_6/Map/symbols.js b/js/src/tests/ecma_6/Map/symbols.js
new file mode 100644
index 000000000..30589a973
--- /dev/null
+++ b/js/src/tests/ecma_6/Map/symbols.js
@@ -0,0 +1,33 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/ */
+
+var m = new Map;
+
+// Symbols can be Map keys.
+var sym = Symbol();
+m.set(sym, "zero");
+assertEq(m.has(sym), true);
+assertEq(m.get(sym), "zero");
+assertEq(m.has(Symbol()), false);
+assertEq(m.get(Symbol()), undefined);
+assertEq([...m][0][0], sym);
+m.set(sym, "replaced");
+assertEq(m.get(sym), "replaced");
+m.delete(sym);
+assertEq(m.has(sym), false);
+assertEq(m.size, 0);
+
+// Symbols returned by Symbol.for() can be Map keys.
+for (var word of "that that is is that that is not is not is that not it".split(' ')) {
+    sym = Symbol.for(word);
+    m.set(sym, (m.get(sym) || 0) + 1);
+}
+assertDeepEq([...m], [
+    [Symbol.for("that"), 5],
+    [Symbol.for("is"), 5],
+    [Symbol.for("not"), 3],
+    [Symbol.for("it"), 1]
+]);
+
+if (typeof reportCompare === "function")
+  reportCompare(0, 0);