anchor.diff:  		?_assertNot(is_valid_spec(""))
   	].
   
  -% smoke_test() ->
  -%     ok = application:start(alphadiamond).
  +smoke_test() ->
  +    ok = application:start(alphadiamond).
   
   -endif.
positive.code: row_for(Letter) ->
  	re:replace(?ROW_TEMPLATE, everything_but(Letter), " ", [global, {return,list}]).
  
  is_valid_spec(Spec) when not size(Spec) =:= 1 -> false;
  % is_valid_spec([H|T]) when length(H) > 1 -> false;
  is_valid_spec(Spec) -> 
  	TrimmedSpec = string:strip(Spec),
  	CleanSpec = re:replace(TrimmedSpec, "[^A-Za-z]", "", [global, {return,list}]),
  	CleanSpec =:= TrimmedSpec.
  
  -ifdef(TEST).
  
  
negative.code: 		?_assertEqual("ABCBA", row_instructions_for("C"))
  	].
  
  valid_spec_test_() ->
  	[
  		?_assert(is_valid_spec("A")),
  		?_assert(is_valid_spec("c")),
  		?_assert(is_valid_spec("  E   ")),
  		?_assertNot(is_valid_spec("AA")),
  		?_assertNot(is_valid_spec(" ")),
  