test-lib: add in-shell "env" replacement

peff · gitster · commit d2554c720789 · 2016-06-01T08:04:08.000-07:00
The one-shot environment variable syntax:

  FOO=BAR some-program

is unportable when some-program is actually a shell
function, like test_must_fail (on some shells FOO remains
set after the function returns, and on others it does not).

We sometimes get around this by using env, like:

  test_must_fail env FOO=BAR some-program

But that only works because test_must_fail's arguments are
themselves a command which can be run. You can't run:

  env FOO=BAR test_must_fail some-program

because env does not know about our shell functions. So
there is no equivalent for test_commit, for example, and one
must resort to:

  (
    FOO=BAR
    export FOO
    test_commit
  )

which is a bit verbose.  Let's add a version of "env" that
works _inside_ the shell, by creating a subshell, exporting
variables from its argument list, and running the command.

Its use is demonstrated on a currently-unportable case in
t4014.

Signed-off-by: Jeff King &lt;peff@peff.net&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
@@ -1072,7 +1072,7 @@ test_expect_success '--from omits redundant in-body header' '
 '
 
 test_expect_success 'in-body headers trigger content encoding' '
-	GIT_AUTHOR_NAME="éxötìc" test_commit exotic &&
+	test_env GIT_AUTHOR_NAME="éxötìc" test_commit exotic &&
 	test_when_finished "git reset --hard HEAD^" &&
 	git format-patch -1 --stdout --from >patch &&
 	cat >expect <<-\EOF &&
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
@@ -939,3 +939,25 @@ mingw_read_file_strip_cr_ () {
 		eval "$1=\$$1\$line"
 	done
 }
+
+# Like "env FOO=BAR some-program", but run inside a subshell, which means
+# it also works for shell functions (though those functions cannot impact
+# the environment outside of the test_env invocation).
+test_env () {
+	(
+		while test $# -gt 0
+		do
+			case "$1" in
+			*=*)
+				eval "${1%%=*}=\${1#*=}"
+				eval "export ${1%%=*}"
+				shift
+				;;
+			*)
+				"$@"
+				exit
+				;;
+			esac
+		done
+	)
+}

Original file line number	Diff line number	Diff line change
`@@ -1072,7 +1072,7 @@ test_expect_success '--from omits redundant in-body header' '`
`1072`	`1072`	`'`
`1073`	`1073`
`1074`	`1074`	`test_expect_success 'in-body headers trigger content encoding' '`
`1075`		`- GIT_AUTHOR_NAME="éxötìc" test_commit exotic &&`
	`1075`	`+ test_env GIT_AUTHOR_NAME="éxötìc" test_commit exotic &&`
`1076`	`1076`	`test_when_finished "git reset --hard HEAD^" &&`
`1077`	`1077`	`git format-patch -1 --stdout --from >patch &&`
`1078`	`1078`	`cat >expect <<-\EOF &&`