[PATCH v2 5/8] test_terminal: give priority to test-terminal.perl usage

[Tay Ray Chuan <rctay89@gmail.com>]

From: Jonathan Nieder <jrnieder@gmail.com>

Tay Ray Chuan wrote:

> [snip]
> 2. For terminal tests that capture output/stderr, the TTY prerequisite
> warning does not quite work for things like
>
>   test_terminal foo >out 2>err
>
> because the warning gets "swallowed" up by the redirection that's
> supposed only to be done by the subcommand.

Good catch.  Such cases (like Jeff's patch) are not well supported
currently. :(

The outcome depends on whether stdout was already a terminal (in which
case test_terminal is a noop) or not (in which case test_terminal
introduces a pseudo-tty in the middle of the pipeline).

	$ test_terminal.perl sh -c 'test -t 1 && echo >&2 YES' >out
	YES
	$ sh -c 'test -t 1 && echo >&2 YES' >out
	$

How about this?

 - use the test_terminal script even when running with "-v"
   if IO::Pty is available, to allow commands like

	test_terminal foo >out 2>err

 - add a separate TTYREDIR prerequisite which is only set
   when the test_terminal script is usable

 - write the "need to declare TTY prerequisite" message to fd 4,
   where it will be printed when running tests with -v, rather
   than being swallowed up by an unrelated redireciton.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
---

  Picked up from a private discussion. I left the discussion in the
  patch message to give some background, and it also gives a nice
  summary of the changes.

 t/lib-terminal.sh |   24 +++++++++++++-----------
 1 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/t/lib-terminal.sh b/t/lib-terminal.sh
index 5e7ee9a..71d147f 100644
--- a/t/lib-terminal.sh
+++ b/t/lib-terminal.sh
@@ -1,36 +1,38 @@
 #!/bin/sh
 
 test_expect_success 'set up terminal for tests' '
-	if test -t 1 && test -t 2
-	then
-		>have_tty
-	elif
+	if
 		test_have_prereq PERL &&
 		"$PERL_PATH" "$TEST_DIRECTORY"/test-terminal.perl \
 			sh -c "test -t 1 && test -t 2"
 	then
 		>test_terminal_works
+	elif test -t 1 && test -t 2
+	then
+		>have_tty
 	fi
 '
 
-if test -e have_tty
-then
-	test_terminal_() { "$@"; }
-	test_set_prereq TTY
-elif test -e test_terminal_works
+if test -e test_terminal_works
 then
 	test_terminal_() {
 		"$PERL_PATH" "$TEST_DIRECTORY"/test-terminal.perl "$@"
 	}
 	test_set_prereq TTY
+	test_set_prereq TTYREDIR
+elif test -e have_tty
+then
+	test_terminal_() { "$@"; }
+	test_set_prereq TTY
+
 else
 	say "# no usable terminal, so skipping some tests"
 fi
 
 test_terminal () {
-	if ! test_declared_prereq TTY
+	if ! test_declared_prereq TTY && ! test_declared_prereq TTYREDIR
 	then
-		echo >&2 'test_terminal: need to declare TTY prerequisite'
+		echo >&4 'test_terminal: need to declare TTY prerequisite'
 		return 127
 	fi
 	test_terminal_ "$@"
-- 
1.7.2.2.513.ge1ef3