tests: use "env" to run commands with temporary env-var settings

Ordinarily, we would say "VAR=VAL command" to execute a tested
command with environment variable(s) set only for that command.
This however does not work if 'command' is a shell function (most
notably 'test_must_fail'); the result of the assignment is retained
and affects later commands.

To avoid this, we used to assign and export environment variables
and run such a test in a subshell, like so:

        (
                VAR=VAL && export VAR &&
                test_must_fail git command to be tested
        )

But with "env" utility, we should be able to say:

        test_must_fail env VAR=VAL git command to be tested

which is much shorter and easier to read.

Signed-off-by: David Tran <unsignedzero@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 6 deletions

diff --git a/t/t6006-rev-list-format.sh b/t/t6006-rev-list-format.sh
index 98744038e..9d9d9de08 100755
--- a/t/t6006-rev-list-format.sh
+++ b/t/t6006-rev-list-format.sh
@@ -190,12 +190,9 @@ test_expect_success '%C(auto) respects --no-color' '
 '
 
 test_expect_success TTY '%C(auto) respects --color=auto (stdout is tty)' '
-	(
-		TERM=vt100 && export TERM &&
-		test_terminal \
-			git log --format=$AUTO_COLOR -1 --color=auto >actual &&
-		has_color actual
-	)
+	test_terminal env TERM=vt100 \
+		git log --format=$AUTO_COLOR -1 --color=auto >actual &&
+	has_color actual
 '
 
 test_expect_success '%C(auto) respects --color=auto (stdout not tty)' '