与下面的收集，什么Linq的语句开始做我需要返回满足测试结果集？
private List<dynamic> _results;
[SetUp]
public void SetUp()
{
_results = new List<dynamic>
{
new {Id = 1, Names = new[] {"n1"}, Tags = new[] {"abc", "def"}},
new {Id = 2, Names = new[] {"n2", "n3"}, Tags = new[] {"ghi"}},
new {Id = 3, Names = new[] {"n1", "n3"}, Tags = new[] {"def", "xyz"}},
new {Id = 4, Names = new[] {"n4"}, Tags = new string[] {}}
};
}
private ILookup<string, string> GetOuterJoinedCollection(IEnumerable<dynamic> results)
{
// ???
}
[Test]
public void Test()
{
ILookup<string, string> list = GetOuterJoinedCollection(_results);
Assert.That(list.Count, Is.EqualTo(4));
Assert.That(list["n1"], Is.EquivalentTo(new [] { "abc", "def", "def", "xyz" }));
Assert.That(list["n2"], Is.EquivalentTo(new [] { "ghi" }));
Assert.That(list["n3"], Is.EquivalentTo(new [] { "ghi", "def", "xyz" }));
Assert.That(list["n4"], Is.EquivalentTo(new string[] { }));
}
注意：这是从以前的问题跟进： 转换成LAMBDA Linq的语句与嵌套的for循环
