TextMessageWriter
TextMessageWriter writes constraint descriptions and messages
            in displayable form as a text stream. It tailors the display
            of individual message components to form the standard message
            format of NUnit assertion failure messages.
            
                
Prefix used for the actual value line of a message
            
Prefix used for the actual difference between actual and expected values if compared with a tolerance
            
Prefix used for the expected value line of a message
            
Length of a message prefix
            
public TextMessageWriter()
Construct a TextMessageWriter
            
Construct a TextMessageWriter, specifying a user message
            and optional formatting arguments.