public void Sub(SimplifiedRational r1, SimplifiedRational r2)
{
RationalBase result = r1.Sub(r2);
Assert.True(r1 != result && r2 != result);
int n1 = r1.Numerator, d1 = r1.Denominator, n2 = r2.Numerator, d2 = r2.Denominator;
Assert.Equal(new SimplifiedRational(n1 * d2 - n2 * d1, d1 * d2), result);
}
public void SubFail(SimplifiedRational r, int n, int d)
{
Assert.Throws <InvalidOperationException>(() => r.Sub(null));
}
