public void GetNextPointOnSpiral_ReturnCorrectCoordinates() { var coefSpiralEquation = 0.5; var anglePhi = 0.0; var deltaAnglePhi = Math.PI / 90; for (var i = 0; i < 100; i++) { var x = Math.Round(coefSpiralEquation * anglePhi * Math.Cos(anglePhi)); var y = Math.Round(coefSpiralEquation * anglePhi * Math.Sin(anglePhi)); spiral.GetNextPointOnSpiral().Should().BeEquivalentTo(new Point((int)x, (int)y)); anglePhi += deltaAnglePhi; } }