OrbitalPeriodTest(double expected_orbital_period,
OrbitingBodyMathematics planet)
{
double orbital_period = planet.get_orbital_period(); // in seconds
double orbital_period_in_days = orbital_period / 60 / 60 / 24;
double acceptable_error = 0.001;
double actual_error = Math.Abs(orbital_period_in_days - expected_orbital_period);
string error_message = differing_results_error_message(
Convert.ToString(orbital_period_in_days),
Convert.ToString(expected_orbital_period),
"days"
);
Assert.LessOrEqual(actual_error, acceptable_error, error_message);
}