blob: f930426e9c792f34d7fbd192417208a1db7715e7 [file] [log] [blame]
// 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 a coin toss with Random.nextBool() is fair.
import "package:expect/expect.dart";
import 'dart:math';
main() {
var seed = new Random().nextInt(1 << 16);
print("coin_test seed: $seed");
var rnd = new Random(seed);
var heads = 0;
var tails = 0;
for (var i = 0; i < 10000; i++) {
if (rnd.nextBool()) {
heads++;
} else {
tails++;
}
}
print("Heads: $heads\n"
"Tails: $tails\n"
"Ratio: ${heads/tails}\n");
Expect.approxEquals(1.0, heads / tails, 0.1);
heads = 0;
tails = 0;
for (var i = 0; i < 10000; i++) {
rnd = new Random(i);
if (rnd.nextBool()) {
heads++;
} else {
tails++;
}
}
print("Heads: $heads\n"
"Tails: $tails\n"
"Ratio: ${heads/tails}\n");
Expect.approxEquals(1.0, heads / tails, 0.1);
// A sequence of newly allocated Random number generators should have fair
// initial tosses.
heads = 0;
tails = 0;
for (var i = 0; i < 10000; i++) {
rnd = new Random();
if (rnd.nextBool()) {
heads++;
} else {
tails++;
}
}
print("Heads: $heads\n"
"Tails: $tails\n"
"Ratio: ${heads/tails}\n");
Expect.approxEquals(1.0, heads / tails, 0.1);
}