[lib/collection] Test for #48282

Change-Id: I62306feab09f8dcd0335daa296b6c744bc139e62
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/231336
Reviewed-by: Lasse Nielsen <[email protected]>
Commit-Queue: Stephen Adams <[email protected]>

Author: rakudrama

tests/lib/collection/map_iterables_consistency_test.dart

@@ -0,0 +1,74 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:collection';
+
+import 'package:expect/expect.dart';
+
+// Test that a Map's keys, values and entries iterables are consistent with
+// their map.
+//
+// While it is generally not permitted to modify a map while iterating the keys,
+// values, or entries, it is possible to iterate these collections in between
+// modifications of the map.
+//
+// See #48282
+
+void check(String kind, Map m) {
+  Expect.equals(0, m.length);
+
+  // These existing iterables
+  final keys = m.keys;
+  final values = m.values;
+  final entries = m.entries;
+
+  for (int i = 0; i < 20; i++) {
+    Expect.equals(i, m.length);
+
+    // Fresh iterables.
+    Expect.equals(i, m.keys.length);
+    Expect.equals(i, m.values.length);
+    Expect.equals(i, m.entries.length);
+
+    Expect.equals(i, List.of(m.keys).length);
+    Expect.equals(i, List.of(m.values).length);
+    Expect.equals(i, List.of(m.entries).length);
+
+    Expect.equals(i, iteratedLength(m.keys));
+    Expect.equals(i, iteratedLength(m.values));
+    Expect.equals(i, iteratedLength(m.entries));
+
+    // Existing iterables.
+    Expect.equals(i, keys.length);
+    Expect.equals(i, values.length);
+    Expect.equals(i, entries.length);
+
+    Expect.equals(i, List.of(keys).length);
+    Expect.equals(i, List.of(values).length);
+    Expect.equals(i, List.of(entries).length);
+
+    Expect.equals(i, iteratedLength(keys));
+    Expect.equals(i, iteratedLength(values));
+    Expect.equals(i, iteratedLength(entries));
+
+    m[i] = i;
+  }
+}
+
+int iteratedLength(Iterable iterable) {
+  int length = 0;
+  final iterator = iterable.iterator;
+  while (iterator.moveNext()) {
+    length++;
+  }
+  return length;
+}
+
+void main() {
+  check('Map', {});
+  check('Map.identity', Map.identity());
+  check('HashMap', HashMap());
+  check('HashMap.identity', HashMap.identity());
+  check('SplayTreeMap', SplayTreeMap());
+}

tests/lib_2/collection/map_iterables_consistency_test.dart

@@ -0,0 +1,76 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// @dart = 2.9
+
+import 'dart:collection';
+
+import 'package:expect/expect.dart';
+
+// Test that a Map's keys, values and entries iterables are consistent with
+// their map.
+//
+// While it is generally not permitted to modify a map while iterating the keys,
+// values, or entries, it is possible to iterate these collections in between
+// modifications of the map.
+//
+// See #48282
+
+void check(String kind, Map m) {
+  Expect.equals(0, m.length);
+
+  // These existing iterables
+  final keys = m.keys;
+  final values = m.values;
+  final entries = m.entries;
+
+  for (int i = 0; i < 20; i++) {
+    Expect.equals(i, m.length);
+
+    // Fresh iterables.
+    Expect.equals(i, m.keys.length);
+    Expect.equals(i, m.values.length);
+    Expect.equals(i, m.entries.length);
+
+    Expect.equals(i, List.of(m.keys).length);
+    Expect.equals(i, List.of(m.values).length);
+    Expect.equals(i, List.of(m.entries).length);
+
+    Expect.equals(i, iteratedLength(m.keys));
+    Expect.equals(i, iteratedLength(m.values));
+    Expect.equals(i, iteratedLength(m.entries));
+
+    // Existing iterables.
+    Expect.equals(i, keys.length);
+    Expect.equals(i, values.length);
+    Expect.equals(i, entries.length);
+
+    Expect.equals(i, List.of(keys).length);
+    Expect.equals(i, List.of(values).length);
+    Expect.equals(i, List.of(entries).length);
+
+    Expect.equals(i, iteratedLength(keys));
+    Expect.equals(i, iteratedLength(values));
+    Expect.equals(i, iteratedLength(entries));
+
+    m[i] = i;
+  }
+}
+
+int iteratedLength(Iterable iterable) {
+  int length = 0;
+  final iterator = iterable.iterator;
+  while (iterator.moveNext()) {
+    length++;
+  }
+  return length;
+}
+
+void main() {
+  check('Map', {});
+  check('Map.identity', Map.identity());
+  check('HashMap', HashMap());
+  check('HashMap.identity', HashMap.identity());
+  check('SplayTreeMap', SplayTreeMap());
+}