public void OptionFilterWhenFalse()
{
Option <int> optionValue = 35;
Option <int> result = OptionModule.Filter(_isEven, optionValue);
Assert.IsTrue(result.IsNone);
}
public void OptionFilterWhenTrue()
{
int expected = 36;
Option <int> optionValue = expected;
Option <int> optionResult = OptionModule.Filter(_isEven, optionValue);
int result = optionResult.Match(value => value, () => 0);
Assert.AreEqual(expected, result);
}
/// <summary>
/// Returns the <paramref name="option"/> if it <see cref="Option{T}.IsSome"/> and the <paramref name="predicate"/> return true when applied it.
/// Otherwise, returns an <see cref="Option{T}.None()"/>.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <param name="predicate">A function that evaluates whether the value contained in the option should remain, or be filtered out.</param>
/// <param name="option">The input option.</param>
/// <returns>
/// Returns <paramref name="option"/> if the option <see cref="Option{T}.IsSome"/> and the <paramref name="predicate"/> function returns true.
/// Otherwise, returns an <see cref="Option{T}.None()"/>.
/// </returns>
public static Option <T> Filter <T>(this Option <T> option, Func <T, bool> predicate)
=> OptionModule.Filter(predicate, option);