[PATCH v3 part 3/3] test: implement and document NOTMUCH_TEST_QUIET variable usage

[Austin Clements]

v3 LGTM.

Quoth Tomi Ollila on Dec 05 at  2:46 pm:
> When NOTMUCH_TEST_QUIET environment variable is set to non-null value
> messages when new test script starts and when test PASSes are disabled.
> This eases picking the cases when tests FAIL (as those are still printed).
> ---
> 
> Diffdiff of part 3 to previous.
> 
> | diff --git a/test/test-lib.sh b/test/test-lib.sh
> | index 9d4a807..d8e0d91 100644
> | --- a/test/test-lib.sh
> | +++ b/test/test-lib.sh
> | @@ -733,9 +733,7 @@ test_failure_ () {
> |  		return
> |  	fi
> |  	test_failure=$(($test_failure + 1))
> | -	if test -n "$NOTMUCH_TEST_QUIET"; then
> | -		print_test_description
> | -	fi
> | +	print_test_description
> |  	test_failure_message_ "FAIL" "$test_subtest_name" "$@"
> |  	test "$immediate" = "" || { GIT_EXIT_OK=t; exit 1; }
> |  	return 1
> 
> 
>  test/README      | 8 ++++++++
>  test/basic       | 4 ++--
>  test/test-lib.sh | 9 ++++++++-
>  3 files changed, 18 insertions(+), 3 deletions(-)