public void ContainsKey_OnlyReturnsTrue_IfValueCanBeLoaded()
{
var dictionary = new LazySelectionDictionary <int, string>(x => x.ToMaybe().Where(y => y != 1).Select(y => y.ToString()));
Assert.IsFalse(dictionary.ContainsKey(1));
Assert.IsTrue(dictionary.ContainsKey(42));
}
public void TryGetValue_InvokesSelectionFunc()
{
var dictionary = new LazySelectionDictionary <int, string>(x => x.ToMaybe().Where(y => y % 2 == 0).Select(y => x.ToString()));
string value = null;
Assert.IsFalse(dictionary.TryGetValue(1, out value));
Assert.IsTrue(dictionary.TryGetValue(2, out value));
Assert.AreEqual("2", value);
}
public void GetValue_EvaluatesOnce()
{
int executed = 0;
var dictionary = new LazySelectionDictionary <int, string>(x => { executed++; return(x.ToString().ToMaybe()); });
string value = dictionary[1];
value = dictionary[1];
Assert.AreEqual("1", value);
Assert.AreEqual(1, executed);
}