eunit-a-lightweight-unit-demo-code

fib.erl

    -module(fib).
    -export([fib/1]).
    -include_lib("eunit/include/eunit.hrl").

    fib(0) -> 1;
    fib(1) -> 1;
    fib(N) when N > 1 -> fib(N-1) + fib(N-2).

    fib_test_() ->
        [?_assert(fib(0) =:= 1),
         ?_assert(fib(1) =:= 1),
         ?_assert(fib(2) =:= 2),
         ?_assert(fib(3) =:= 3),
         ?_assert(fib(4) =:= 5),
         ?_assert(fib(5) =:= 8),
         ?_assertException(error, function_clause, fib(-1)),
         ?_assert(fib(31) =:= 2178309)
        ].