[PATCH bc/hash-independent-tests-part-4] t: decrease nesting in test_oid_to_path

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Aug 8, 2019, 06:56 UTC
Message-ID: <20190808065614.GA209195@google.com>
In-Reply-To: <20190628225928.622372-2-sandals@crustytoothpaste.net>

t1410.3 ("corrupt and checks") fails when run using dash versions before 0.5.8, with a cryptic message:

	mv: cannot stat '.git/objects//e84adb2704cbd49549e52169b4043871e13432': No such file or directory

The function generating that path:

	test_oid_to_path () {
		echo "${1%${1#??}}/${1#??}"
	}

which is supposed to produce a result like

	12/3456789....

But a dash bug[*] causes it to instead expand to

	/3456789...

The stream of symbols that makes up this function is hard for humans to follow, too. The complexity mostly comes from the repeated use of the expression ${1#??} for the basename of the loose object. Use a variable instead --- nowadays, the dialect of shell used by Git permits local variables, so this is cheap.

An alternative way to work around [*] is to remove the double-quotes around test_oid_to_path's return value. That makes the expression easier for dash to read, but harder for humans. Let's prefer the rephrasing that's helpful for humans, too.

Noticed by building on Ubuntu trusty, which uses dash 0.5.7.

[*] Fixed by v0.5.8~13 ("[EXPAND] Propagate EXP_QPAT in subevalvar, 2013-08-23).

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
 t/test-lib-functions.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 7860491660..de58e8b502 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -1337,7 +1337,8 @@ test_oid () {
 # Insert a slash into an object ID so it can be used to reference a location
 # under ".git/objects".  For example, "deadbeef..." becomes "de/adbeef..".
 test_oid_to_path () {
-	echo "${1%${1#??}}/${1#??}"
+	local basename=${1#??}
+	echo "${1%$basename}/$basename"
 }
 
 # Choose a port number based on the test script's number and store it in

-- 
2.23.0.rc1.153.gdeed80330f