Error "TOMTreeGenerator.GetElementAbsoluteType: Object reference not set to an instance of an object".How to resolve this Error while performing UnitTesting for Schemas ?

This error occurs because of the schema testing limitation for the Schemas containing any imported schema/schemas.

This can be overcome by creating custom method, (instead of using the ValidateSchema method created by the BizTalk) and writing manual code to test the Input XML against the Schema.

(For eg: using XmlReaderSettings methods or any other possible methods whatever you think will get the logic done.)