public void ShouldSuccessCalculateIntegralViaLeftRectMethodRelative(double a, double b, int n, double expectedResult, int eps)
        {
            IntegrateOptions options = new IntegrateOptions()
            {
                StartX   = a,
                EndX     = b,
                Steps    = n,
                Function = TestFunc
            };
            double actualResult = Integrals.LeftRect(options);

            Assert.IsTrue(Math.Abs(expectedResult - actualResult) / Math.Abs(expectedResult) * 100 <= eps);
        }