They sent my an incomplete chat application source code in C# (Solution of 3 projects: WebService, , WInForms App, Web App)
The app should enable multi users to post chat messages to each others and veiw and export chat history
I could select either Web or Desktop to implement
Desktop code has only buttons with empty event handlers that I should handle
But WebService has almost complete except one method
The trick was to get the app functional with proper threading handling and exception handling along with clean/standard/organized/optimized code with comments
It was easy with some search effort for code pieces I did not touch for long time like writing ADO code
however, I needed more 30 minutes to get it done