Tuesday, February 04, 2014

Using API docs as a test aid

I wrote about my custom documentation using Lua embedded in my C source. With the complete description of the function - its arguments [and their type], return type etc, can we do more with it?
I wanted some test stubs for the Lua APIs (that I am defining from my C back-end) and all I had to do, was re-define the mydoc function which will consume the same data, but instead of generating documentation, generate some Lua code to test the APIs.
i.e, if I have a function that takes a number and returns a string (on success) and nil on failure, I generate:
function Stub.test (n)
  assert(type(n) == 'number', 'n should be a number)
  if g_nil_path then return nil end
  return 'rand-str'

With this, I can see and get a feel of the Lua APIs that my C functions are exposing, also I can invoke the user scripts just to check the argument types for correctness, and I can exercise the success path as well as the failure path by setting the global g_nil_path. And of course for more randomness, I use 
 when I return a number and
string.rep(string.char(math.random(65,90)), math.random(1,10)) 
when returning strings.

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