public void AddTest(double re1, double im1, double re2, double im2, double re3, double im3)
{
//arrange
Complex c1 = new Complex(re1, im1);
Complex c2 = new Complex(re2, im2);
Complex expected = new Complex(re3, im3);
//action
Complex actual = Complex.Add(c1, c2);
//assert
expected.Should().Be(actual);
}