public void SelectChromosomes_Generation_ChromosomesSelected()
{
var target = new StochasticUniversalSamplingSelection();
var c1 = new ChromosomeStub();
c1.Fitness = 0.1;
var c2 = new ChromosomeStub();
c2.Fitness = 0.5;
var c3 = new ChromosomeStub();
c3.Fitness = 0;
var c4 = new ChromosomeStub();
c4.Fitness = 0.7;
var generation = new Generation(1, new List<IChromosome>() {
c1, c2, c3, c4
});
// Fitness sum: 0.1 + 0.5 + 0 + 0.7 = 1.3
// c1: 8% = 0.08
// c2: 38% = 0.46
// c3: 0% = 0.46
// c4: 54% = 1.00
var rnd = MockRepository.GenerateMock<IRandomization>();
rnd.Expect(r => r.GetDouble()).Return(0.3);
RandomizationProvider.Current = rnd;
// Step size 1/2 = 0.5
var actual = target.SelectChromosomes(2, generation);
Assert.AreEqual(2, actual.Count);
Assert.AreEqual(c2.Fitness, actual[0].Fitness); // 0.3
Assert.AreEqual(c4.Fitness, actual[1].Fitness); // 0.8
// Step size 1/3 = 0.33
actual = target.SelectChromosomes(3, generation);
Assert.AreEqual(3, actual.Count);
Assert.AreEqual(c2.Fitness, actual[0].Fitness); // 0.3
Assert.AreEqual(c4.Fitness, actual[1].Fitness); // 0.63
Assert.AreEqual(c4.Fitness, actual[2].Fitness); // 0.96
// Step size 1/4 = 0.25
actual = target.SelectChromosomes(4, generation);
Assert.AreEqual(4, actual.Count);
Assert.AreEqual(c2.Fitness, actual[0].Fitness); // 0.3
Assert.AreEqual(c4.Fitness, actual[1].Fitness); // 0.55
Assert.AreEqual(c4.Fitness, actual[2].Fitness); // 0.80
Assert.AreEqual(c1.Fitness, actual[3].Fitness); // 0.05
// Step size 1/5 = 0.20
actual = target.SelectChromosomes(5, generation);
Assert.AreEqual(5, actual.Count);
Assert.AreEqual(c2.Fitness, actual[0].Fitness); // 0.3
Assert.AreEqual(c4.Fitness, actual[1].Fitness); // 0.5
Assert.AreEqual(c4.Fitness, actual[2].Fitness); // 0.7
Assert.AreEqual(c4.Fitness, actual[3].Fitness); // 0.9
Assert.AreEqual(c2.Fitness, actual[4].Fitness); // 0.1
}
public void SelectChromosomes_NullGeneration_Exception()
{
var target = new StochasticUniversalSamplingSelection();
ExceptionAssert.IsThrowing(new ArgumentNullException("generation"), () =>
{
target.SelectChromosomes(2, null);
});
}
public void SelectChromosomes_InvalidNumber_Exception()
{
var target = new StochasticUniversalSamplingSelection();
ExceptionAssert.IsThrowing(new ArgumentOutOfRangeException("number", "The number of selected chromosomes should be at least 2."), () =>
{
target.SelectChromosomes(-1, null);
});
ExceptionAssert.IsThrowing(new ArgumentOutOfRangeException("number", "The number of selected chromosomes should be at least 2."), () =>
{
target.SelectChromosomes(0, null);
});
ExceptionAssert.IsThrowing(new ArgumentOutOfRangeException("number", "The number of selected chromosomes should be at least 2."), () =>
{
target.SelectChromosomes(1, null);
});
}