| // Copyright (c) 2012, 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. |
| |
| // Test that the default PRNG does uniformly distribute values when not using |
| // a power of 2. |
| |
| // Library tag to allow Dartium to run the test. |
| library low_test; |
| |
| import "package:expect/expect.dart"; |
| import 'dart:math'; |
| |
| void main() { |
| var n = (2 * (1 << 32)) ~/ 3; |
| var n2 = n ~/ 2; |
| |
| var iterations = 200000; |
| |
| var seed = new Random().nextInt(1 << 16); |
| print("low_test seed: $seed"); |
| var prng = new Random(seed); |
| |
| var low = 0; |
| for (var i = 0; i < iterations; i++) { |
| if (prng.nextInt(n) < n2) { |
| low++; |
| } |
| } |
| |
| var diff = (low - (iterations ~/ 2)).abs(); |
| print("$low, $diff"); |
| Expect.isTrue(diff < (iterations ~/ 20)); |
| } |