Running tests in nil_test.go

We run three tests, where two test cases will pass and one will fail. This way we can see the tick mark and cross mark in action:

$ go test -v ./nil_test.go                                          
=== RUN   TestServer                       
=== RUN   TestServer/Request_correct_URL   
=== RUN   TestServer/Request_incorrect_URL 
=== RUN   TestServer/Fail_for_no_reason    
--- FAIL: TestServer (0.00s)               
  --- PASS: TestServer/Request_correct_URL (0.00s)                                  
        nil_test.go:55: Got 1. == Got 1.  
  --- PASS: TestServer/Request_incorrect_URL (0.00s)                                
        nil_test.go:55: Got None. == Got None. 
  --- FAIL: TestServer/Fail_for_no_reason (0.00s)   
      nil_test.go:59: + != - 
 FAIL
 exit status 1
 FAIL command-line-arguments 0.003s