test: format disk image through loopback device

It seems that the change on the image file sometimes not propagated on
the loopback device immediately.

diff --git a/test/units/testsuite-58.sh b/test/units/testsuite-58.sh
index 1ebc699a1b044d1faaf4d8a0295285f38975024b..cc755a4f86dbb7ebc9d0827f8bb96a826b3577b4 100755 (executable)
--- a/test/units/testsuite-58.sh
+++ b/test/units/testsuite-58.sh
@@ -174,7 +174,7 @@ rm -r /tmp/testsuite-58.3-defs/
 mkdir -p /tmp/testsuite-58-issue-21817-defs/
 truncate -s 100m /var/tmp/testsuite-58-issue-21817.img
 LOOP=$(losetup -P --show -f /var/tmp/testsuite-58-issue-21817.img)
-printf 'size=50M,type=%s\n,\n' "${root_guid}" | sfdisk -X gpt /var/tmp/testsuite-58-issue-21817.img
+printf 'size=50M,type=%s\n,\n' "${root_guid}" | sfdisk -X gpt "$LOOP"
 cat >/tmp/testsuite-58-issue-21817-defs/test.conf <<EOF
 [Partition]
 Type=root