We need have tests covering DataContractSerializer serializing the following types.
Refer https://github.com/dotnet/corefx/blob/master/src/System.Runtime.Serialization.Xml/tests/DataContractSerializer.cs on how to add the DCS tests using the common helper method.
#21982

• System.Collections.Generic.LongEnumEqualityComparer`1[[System.Runtime.Serialization.Formatters.Tests.UInt64Enum]]
• System.Collections.Generic.EnumEqualityComparer`1[[System.Runtime.Serialization.Formatters.Tests.UInt32Enum]]
• System.Collections.Generic.SByteEnumEqualityComparer`1[[System.Runtime.Serialization.Formatters.Tests.SByteEnum]]
• System.Collections.Generic.ShortEnumEqualityComparer`1[[System.Runtime.Serialization.Formatters.Tests.Int16Enum]]
• System.Collections.Generic.SortedList`2[[System.Int32],[System.Runtime.Serialization.Formatters.Tests.Point]]
• System.Collections.ObjectModel.ObservableCollection`1[[System.Int32]] // The implementations between core and netfx are completely different. I don't think serialization works here without a custom serialization routine
• System.Collections.ObjectModel.ReadOnlyDictionary`2[[System.Int32],[System.String]]
• System.Collections.ObjectModel.ReadOnlyObservableCollection`1[[System.Int32]]
• System.Collections.Specialized.ListDictionary
• System.Collections.Specialized.StringCollection