Make zone variables accept any value as key.

tests/lib/async/zone_value_test.dart

Index: tests/lib/async/zone_value_test.dart
diff --git a/tests/lib/async/zone_value_test.dart b/tests/lib/async/zone_value_test.dart
index 8aa7c852a2d1b0a09d95f6bf268ceafb36b8b913..438227ce0469a10e5f04cc5c69db964cb1ac9ee7 100644
--- a/tests/lib/async/zone_value_test.dart
+++ b/tests/lib/async/zone_value_test.dart
@@ -7,48 +7,142 @@ import 'package:async_helper/async_helper.dart';
 import 'dart:async';
 
 main() {
-  Completer done = new Completer();
-  List events = [];
+  // Unique object.
+  var baz = new Object();
+  // Not so unique object that thinks it's the same as baz.
+  var mimic = new Mimic(baz);
 
   // runGuarded calls run, captures the synchronous error (if any) and
   // gives that one to handleUncaughtError.
 
   Expect.identical(Zone.ROOT, Zone.current);
-  Zone forked;
+
+  // Create a map with various key types.
   Map zoneValues = new Map();
-  var foo = const Symbol("foo");
-  var bar = const Symbol("bar");
-  zoneValues[foo] = 499;
-  zoneValues[bar] = [];
-  forked = Zone.current.fork(zoneValues: zoneValues);
+  zoneValues[#foo] = 499;
+  zoneValues["bar"] = [];
+  zoneValues[baz] = "baz";
+  zoneValues[0] = "zero!";
+  zoneValues[null] = baz;
+
+  Zone forked = Zone.current.fork(zoneValues: zoneValues);
 
+  // Values are not present when not inside the zone.
   Expect.identical(Zone.ROOT, Zone.current);
-  Expect.isNull(Zone.current[foo]);
-  Expect.isNull(Zone.current[bar]);
+  Expect.isNull(Zone.current[#foo]);
+  Expect.isNull(Zone.current["bar"]);
+  Expect.isNull(Zone.current[baz]);
+  Expect.isNull(Zone.current[mimic]);
+  Expect.isNull(Zone.current[0]);
+  Expect.isNull(Zone.current[null]);
+  Expect.isNull(Zone.current["qux"]);
+
+  // Changing the original map has no effect after the zone is created.
+  zoneValues[#foo] = -1;
+
+  // Values are available directly on the zone.
+  Expect.equals(499, forked[#foo]);
+  Expect.listEquals([], forked["bar"]);
+  Expect.equals("baz", forked[baz]);
+  Expect.isNull(Zone.current[mimic]);
+  Expect.equals("zero!", forked[0]);
+  Expect.equals("zero!", forked[0.0]);  // Lookup uses equality.
+  Expect.equals("zero!", forked[-0.0]);
+  Expect.equals(baz, forked[null]);
+  Expect.isNull(forked["qux"]);
 
   forked.run(() {
-    Expect.equals(499, Zone.current[foo]);
-    Expect.listEquals([], Zone.current[bar]);
-    Zone.current[bar].add(42);
+    Expect.identical(forked, Zone.current);  // Sanity check.
+    // Values are present on current when inside zone.
+    Expect.equals(499, Zone.current[#foo]);
+    Expect.listEquals([], Zone.current["bar"]);
+    Expect.equals("baz", Zone.current[baz]);
+    Expect.isNull(Zone.current[mimic]);
+    Expect.equals("zero!", Zone.current[0]);
+    Expect.equals("zero!", Zone.current[0.0]);  // Lookup uses equality.
+    Expect.equals("zero!", Zone.current[-0.0]);
+    Expect.equals(baz, Zone.current[null]);
+    Expect.isNull(Zone.current["qux"]);
   });
+
+  // Values are still not present when not inside the zone.
   Expect.identical(Zone.ROOT, Zone.current);
-  Expect.isNull(Zone.current[foo]);
-  Expect.isNull(Zone.current[bar]);
+  Expect.isNull(Zone.current[#foo]);
+  Expect.isNull(Zone.current["bar"]);
+  Expect.isNull(Zone.current[baz]);
+  Expect.isNull(Zone.current[mimic]);
+  Expect.isNull(Zone.current[0]);
+  Expect.isNull(Zone.current[null]);
+  Expect.isNull(Zone.current["qux"]);
+
+  // Modifying the stored values work as expected.
+  zoneValues["bar"].add(42);
 
   forked.run(() {
-    Expect.equals(499, Zone.current[foo]);
-    Expect.listEquals([42], Zone.current[bar]);
+    Expect.identical(forked, Zone.current);  // Sanity check.
+    // Values are still there when inside the zone. The list was modified.
+    Expect.equals(499, Zone.current[#foo]);
+    Expect.listEquals([42], Zone.current["bar"]);
+    Expect.equals("baz", Zone.current[baz]);
+    Expect.isNull(Zone.current[mimic]);
+    Expect.equals("zero!", Zone.current[0]);
+    Expect.equals(baz, Zone.current[null]);
+    Expect.isNull(Zone.current["qux"]);
   });
 
+  // Creating a further nested zone with new values allows keeping, overriding,
+  // and shadowing existing values from the outer zone.
   zoneValues = new Map();
-  var gee = const Symbol("gee");
-  zoneValues[gee] = 99;
-  zoneValues[foo] = -499;
+  zoneValues[#foo] = -499;     // Values can be overridden.
+  zoneValues["bar"] = null;    // Values can be changed to null.
+  zoneValues["qux"] = 99;      // Values can be added
+  // Overriding with equal, but not identical, key is possible.
+  zoneValues[mimic] = "floo";
+  zoneValues[0.0] = "zero!ZERO!";
+
   Zone forkedChild = forked.fork(zoneValues: zoneValues);
 
+  // New values available on zone.
+  Expect.equals(-499, forkedChild[#foo]);         // Overridden.
+  Expect.isNull(forkedChild["bar"]);              // Overridden to null.
+  Expect.equals("floo", forkedChild[baz]);        // Overridden by mimic.
+  Expect.equals("floo", forkedChild[mimic]);      // Now recognizes mimic.
+  Expect.equals("zero!ZERO!", forkedChild[0]);    // Overridden by 0.0.
+  Expect.equals("zero!ZERO!", forkedChild[0.0]);  // Overriding 0.
+  Expect.equals(baz, forkedChild[null]);          // Inherited.
+  Expect.equals(99, forkedChild["qux"]);          // Added.
+
   forkedChild.run(() {
-    Expect.equals(-499, Zone.current[foo]);
-    Expect.listEquals([42], Zone.current[bar]);
-    Expect.equals(99, Zone.current[gee]);
+    Expect.identical(forkedChild, Zone.current);  // Sanity check.
+    // New values available on current zone when the zone is current.
+    Expect.equals(-499, Zone.current[#foo]);         // Overridden.
+    Expect.isNull(Zone.current["bar"]);              // Overridden to null.
+    Expect.equals("floo", Zone.current[baz]);        // Overridden by mimic.
+    Expect.equals("floo", Zone.current[mimic]);      // Now recognizes mimic.
+    Expect.equals("zero!ZERO!", Zone.current[0]);    // Overridden by 0.0.
+    Expect.equals("zero!ZERO!", Zone.current[0.0]);  // Overriding 0.
+    Expect.equals(baz, Zone.current[null]);          // Inherited.
+    Expect.equals(99, Zone.current["qux"]);          // Added.
   });
-}
+
+  // Parent zone values are unchanged.
+  Expect.equals(499, forked[#foo]);
+  Expect.listEquals([42], forked["bar"]);
+  Expect.equals("baz", forked[baz]);
+  Expect.isNull(Zone.current[mimic]);
+  Expect.equals("zero!", forked[0]);
+  Expect.equals("zero!", forked[0.0]);  // Lookup uses equality.
+  Expect.equals("zero!", forked[-0.0]);
+  Expect.equals(baz, forked[null]);
+  Expect.isNull(forked["qux"]);
+}
+
+// Class of objects that consider themselves equal to their originals.
+// Sees through mimickry.
+class Mimic {
+  final Object original;
+  Mimic(this.original);
+  int get hashCode => original.hashCode;
+  bool operator==(Object other) =>
+      (other is Mimic) ? this == other.original : original == other;
+}