erlang - What's the point of meck:validate? -

as newcomer meck, i've been putting test shows various features. cannot, however, understand why developer might call meck:validate. here's example:

-module(meck_demo).  -include_lib("eunit/include/eunit.hrl").  validate_is_of_limited_use_test_() ->     { foreach, fun setup_mock/0, fun cleanup_mock/1,        [fun validate_does_not_fail_if_a_function_is_not_called/0,        fun validate_does_not_fail_if_a_function_is_called_with_wrong_arity/0,        fun validate_does_not_fail_if_an_undefined_function_is_called/0,        fun validate_does_fail_if_a_function_was_called_with_wrong_argument_types/0,        fun validate_does_fail_if_expectation_throws_an_unexpected_exception/0 ]}.  validate_does_not_fail_if_a_function_is_not_called() ->     meck:expect(womble, name, fun() -> "wellington" end),        ?assert(meck:validate(womble)).  validate_does_not_fail_if_a_function_is_called_with_wrong_arity() ->     meck:expect(womble, name, fun() -> "madame cholet" end),     ?asserterror(undef, womble:name(unexpected_arg)),     ?assert(meck:validate(womble)).  validate_does_not_fail_if_an_undefined_function_is_called() ->     ?asserterror(undef, womble:fly()),     ?assert(meck:validate(womble)).  validate_does_fail_if_a_function_was_called_with_wrong_argument_types() ->     meck:expect(womble, jump, fun(height) when height < 1 ->                                  ok                               end),     ?asserterror(function_clause, womble:jump(999)),     ?assertnot(meck:validate(womble)).  validate_does_fail_if_expectation_throws_an_unexpected_exception() ->     meck:expect(womble, jump, fun(height) -> 42 = height end),     ?asserterror({badmatch, 999}, womble:jump(999)),     ?assertnot(meck:validate(womble)).     setup_mock() ->     meck:new(womble, [non_strict]).  cleanup_mock(_setupresult) ->     meck:unload(womble). 

what missing?

-- updated reflect cases adam explains can caught

you managed hit every case not covered validate (added better documentation in 10c5063).

validate can detect:

• when function called wrong argument types (function_clause)
• when exception thrown
• when exception thrown , expected (via meck:exception/2), still results in true being return meck:validate/1

validate cannot detect:

• when didn't call function
• when called function wrong number of arguments
• if called undefined function

the reason cannot detect these cases because of how mock implemented. meck replaces module mock , process maintains mock. meck gets goes through mock module. meck not insert @ caller level (i.e. in module or in test case), cannot know failed call module. of failures in test case above never reaches mock module in first place.