public void TestEmptyDictionary()
{
ImmutableSortedTreeDictionary <int, int> .Builder dictionary = ImmutableSortedTreeDictionary.CreateBuilder <int, int>();
ImmutableSortedTreeDictionary <int, int> .Builder.KeyCollection keys = dictionary.Keys;
ImmutableSortedTreeDictionary <int, int> .Builder.ValueCollection values = dictionary.Values;
Assert.Empty(dictionary);
Assert.Empty(keys);
Assert.Empty(values);
#pragma warning disable xUnit2013 // Do not use equality check to check for collection size.
Assert.Equal(0, dictionary.Count);
Assert.Equal(0, keys.Count);
Assert.Equal(0, values.Count);
#pragma warning restore xUnit2013 // Do not use equality check to check for collection size.
Assert.False(dictionary.ContainsKey(0));
Assert.False(dictionary.ContainsValue(0));
Assert.False(dictionary.TryGetValue(0, out _));
Assert.Equal(0, dictionary.GetValueOrDefault(0));
Assert.Equal(1, dictionary.GetValueOrDefault(0, 1));
Assert.Throws <KeyNotFoundException>(() => dictionary[0]);
#pragma warning disable xUnit2017 // Do not use Contains() to check if a value exists in a collection
Assert.False(keys.Contains(0));
Assert.False(values.Contains(0));
#pragma warning restore xUnit2017 // Do not use Contains() to check if a value exists in a collection
}