One view  says that First John is a series of tests of salvation. Robert Law popularized  this  view, saying First John was about tests of eternal life. Another, John MacArthur, says that there are eleven tests  of salvation in First John. He wrote a book called "Saved Without a Doubt" that walks you through these.  Another however, says First John's focus is tests of fellowship. Dwight Pentecost was probably one of the  first  to  popularize this  view.  There's also an interesting third view, which  says First John was  written  as tests of experiencing eternal life. 

So which is it? How are these understood, how are they applied, what is the result of application?