public void GetPairsWithApproximateMinimumCost_ReturnsOnePair_ForTwoElementSequence()
{
var result = Pairing.GetPairsWithApproximateMinimumCost(new[] { 1, 2 }, DistanceCostOfPairsEvaluator);
Assert.AreEqual(1, result.Length);
Assert.IsTrue(result[0].Equals((1, 2)) || result[0].Equals((2, 1)));
}
public void GetPairsWithApproximateMinimumCost_OperatesAsExpected_AtLargeInputs(int length)
{
var random = new Random();
var sequence = new List <int>();
var expected = new Dictionary <int, int>();
for (var i = 0; i < length; i++)
{
var item = random.Next(length);
sequence.Add(item);
expected.AddOrUpdate(item, 1, e => e + 1);
}
var result = Pairing.GetPairsWithApproximateMinimumCost(sequence, DistanceCostOfPairsEvaluator);
foreach (var r in result)
{
var x = new[] { r.Item1, r.Item2 };
foreach (var item in x)
{
Assert.IsTrue(expected.TryGetValue(item, out var appearances));
if (appearances == 1)
{
expected.Remove(item);
}
else
{
expected[item] = appearances - 1;
}
}
}
Assert.AreEqual(0, expected.Count);
}
public void GetPairsWithApproximateMinimumCost_ApproximatesAtExpectedError(int length, int samples,
int iterations,
double expectedMaxError)
{
var totalError = .0;
for (var it = 0; it < samples; it++)
{
var random = new Random(Environment.TickCount);
var sequence = new List <int>();
for (var i = 0; i < length; i++)
{
var item = random.Next(length);
sequence.Add(item);
}
var approxResult =
Pairing.GetPairsWithApproximateMinimumCost(sequence, DistanceCostOfPairsEvaluator, iterations);
var approxCost = approxResult.Sum(s => DistanceCostOfPairsEvaluator(s.Item1, s.Item2));
sequence.Sort();
var minCost = .0;
var maxCost = .0;
for (var i = 0; i < sequence.Count; i += 2)
{
minCost += DistanceCostOfPairsEvaluator(sequence[i], sequence[i + 1]);
maxCost += DistanceCostOfPairsEvaluator(sequence[i], sequence[sequence.Count - i - 1]);
}
var error = 1 - (maxCost - approxCost) / (maxCost - minCost);
if (double.IsNaN(error))
{
error = 0;
}
totalError += error;
}
totalError /= samples;
Assert.IsTrue(totalError <= expectedMaxError,
$"Total error {totalError * 100:N}% should be less than or equal to {expectedMaxError * 100:N}%");
}
public void GetPairsWithApproximateMinimumCost_ThrowsException_ForZeroOrLessIterationCount()
{
Assert.Throws <ArgumentOutOfRangeException>(
() => Pairing.GetPairsWithApproximateMinimumCost(new[] { 1, 2 }, DistanceCostOfPairsEvaluator, 0));
}
public void GetPairsWithApproximateMinimumCost_ThrowsException_ForSequenceWithOddNumberOfElements()
{
Assert.Throws <ArgumentException>(
() => Pairing.GetPairsWithApproximateMinimumCost(new[] { 1, 2, 3 }, DistanceCostOfPairsEvaluator));
}
public void GetPairsWithApproximateMinimumCost_ThrowsException_ForNullSequence()
{
Assert.Throws <ArgumentNullException>(
() => Pairing.GetPairsWithApproximateMinimumCost <int>(null, DistanceCostOfPairsEvaluator));
}
public void GetPairsWithApproximateMinimumCost_ThrowsException_ForNullEvaluateCostOfPairFunc()
{
Assert.Throws <ArgumentNullException>(
() => Pairing.GetPairsWithApproximateMinimumCost(new[] { 1, 2 }, null));
}
public void GetPairsWithApproximateMinimumCost_ReturnsEmptyArray_ForEmptySequence()
{
var result = Pairing.GetPairsWithApproximateMinimumCost(new int[] { }, DistanceCostOfPairsEvaluator);
TestHelper.AssertSequence(result);
}
