One of the most common situation, how will you start Testing without any functional requirement specification or any related documents? No wonder there are sometimes these kind of situations, ex. Resource attrition, no-documentation-with-agile-projects, etc. The only hope in these situations is ‘Exploratory Testing’. Since there are no documents to refer, refer the application directly ? Explore it, Test it. Gradually the flows make sense and we actually start testing it. Other option is to sit with Business analysts and developers to get application understanding – listening to experts instead of reading a document.