How to: Add Trace Statements to Application Code
The methods used most often for tracing are the methods for writing output to listeners: Write, WriteIf, WriteLine, WriteLineIf, Assert, and Fail. These methods can be divided into two categories: Write, WriteLine, and Fail all emit output unconditionally, whereas WriteIf, WriteLineIf, and Assert test a Boolean condition, and write or do not write based on the value of the condition. WriteIf and WriteLineIf emit output of the condition is true, and Assert emits output if the condition is false.
When designing your tracing and debugging strategy, you should think about how you want the output to look. Multiple Write statements filled with unrelated information will create a log that is difficult to read. On the other hand, using WriteLine to put related statements on separate lines may make it difficult to distinguish what information belongs together. In general, use multiple Write statements when you want to combine information from multiple sources to create a single informative message, and the WriteLine statement when you want to create a single, complete message.
To write a complete line
To write a partial line
To verify that certain conditions exist either before or after you execute a method
Call the Assert method.