On Tue, 17 Jan 2012 18:26:41 +0400, Dmitry Kurochkin <dmitry.kurochkin@gmail.com> wrote:
> Sorry, I still do not understand why we can not implement
> test_emacs_expect_t() like:
> 
>   result=${test_emacs $@}
>   test_expect_equal $result t
> 
> Can you please explain?

In the failure case test_expect_equal does:

  test_failure_ "$test_subtest_name" "$(diff -u $testname.expected $testname.output)"

that diff output is not useful here, because the test harness doesn't
have any expected output other than `t' with which to diff the actual
output.

The emacs-address-cleaning test shows how we will provide expected
vs. actual output directly from within emacs, making it easier for the
developer to figure out what went wrong.