public void ToLookupNullKey()
{
Country china, india, unknown;
Data<Country> data = Data
(
china = new Country { Name = "China", Continent = "Asia" },
india = new Country { Name = "India", Continent = "Asia" },
unknown = new Country { Name = "Unknown", Continent = null }
);
ILookup<string, Country> continentLookup = data.ToLookup(x => x.Continent);
using (IEnumerator<IGrouping<string, Country>> enumerator = continentLookup.GetEnumerator())
{
Assert.That(enumerator.MoveNext(), Is.True);
Assert.That(enumerator.Current.Key, Is.EqualTo("Asia"));
enumerator.Current.AssertSame(china, india);
Assert.That(enumerator.MoveNext(), Is.True);
Assert.That(enumerator.Current.Key, Is.EqualTo(null));
enumerator.Current.AssertSame(unknown);
Assert.That(enumerator.MoveNext(), Is.False);
}
}
public void ThenByDescendingNullKey()
{
Country england, france, china, india, unknown;
Data<Country> data = Data
(
england = new Country() { Name = "England", Continent = "Europe" },
france = new Country() { Name = "France", Continent = "Europe" },
china = new Country() { Name = "China", Continent = "Asia" },
india = new Country() { Name = "India", Continent = "Asia" },
unknown = new Country() { Name = "Unknown", Continent = null }
);
IOrderedEnumerable<Country> orderedData = data.OrderBy(x => true).ThenByDescending(x => x.Continent);
orderedData.AssertSame(england, france, china, india, unknown);
}
public void ToLookupNullElementInSource()
{
Country china, india, @null;
Data<Country> data = Data
(
china = new Country { Name = "China", Continent = "Asia" },
india = new Country { Name = "India", Continent = "Asia" },
@null = null
);
ILookup<Country, Country> lookup = data.ToLookup(x => x);
using (IEnumerator<IGrouping<Country, Country>> enumerator = lookup.GetEnumerator())
{
Assert.That(enumerator.MoveNext(), Is.True);
Assert.That(enumerator.Current.Key, Is.SameAs(china));
enumerator.Current.AssertSame(china);
Assert.That(enumerator.MoveNext(), Is.True);
Assert.That(enumerator.Current.Key, Is.SameAs(india));
enumerator.Current.AssertSame(india);
Assert.That(enumerator.MoveNext(), Is.True);
Assert.That(enumerator.Current.Key, Is.SameAs(@null));
enumerator.Current.AssertSame(@null);
Assert.That(enumerator.MoveNext(), Is.False);
}
}
public void ThenByWithComparerNullKey()
{
Country england, france, china, india, unknown;
Data<Country> data = Data
(
england = new Country() { Name = "England", Continent = "Europe" },
france = new Country() { Name = "France", Continent = "Europe" },
china = new Country() { Name = "China", Continent = "Asia" },
india = new Country() { Name = "India", Continent = "Asia" },
unknown = new Country() { Name = "Unknown", Continent = null }
);
IOrderedEnumerable<Country> orderedData = data.OrderBy(x => true).ThenBy(x => x.Continent, Comparer<string>.Default);
orderedData.AssertSame(unknown, china, india, england, france);
}