diff --git a/test/units/testsuite-58.sh b/test/units/testsuite-58.sh
index 8dadcc0a95..bf6c77ef98 100755
--- a/test/units/testsuite-58.sh
+++ b/test/units/testsuite-58.sh
@@ -8,76 +8,86 @@ if ! command -v systemd-repart &>/dev/null; then
     exit 0
 fi
 
+# shellcheck source=test/units/assert.sh
+. "$(dirname "$0")"/assert.sh
+
 export SYSTEMD_LOG_LEVEL=debug
 export PAGER=cat
 
+seed=750b6cd5c4ae4012a15e7be3c29e6a47
+
 machine="$(uname -m)"
 if [ "${machine}" = "x86_64" ]; then
-    root_guid=4f68bce3-e8cd-4db1-96e7-fbcaf984b709
+    root_guid=4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709
     root_uuid=60F33797-1D71-4DCB-AA6F-20564F036CD0
-    usr_guid=8484680c-9521-48c6-9c11-b0720656f69e
+    usr_guid=8484680C-9521-48C6-9C11-B0720656F69E
     usr_uuid=7E3369DD-D653-4513-ADF5-B993A9F20C16
     architecture="x86-64"
 elif [ "${machine}" = "i386" ] || [ "${machine}" = "i686" ] || [ "${machine}" = "x86" ]; then
-    root_guid=44479540-f297-41b2-9af7-d131d5f0458a
-    root_uuid=02b4253f-29a4-404e-8972-1669d3b03c87
-    usr_guid=75250d76-8cc6-458e-bd66-bd47cc81a812
-    usr_uuid=7b42ffb0-b0e1-4395-b20b-c78f4a571648
+    root_guid=44479540-F297-41B2-9AF7-D131D5F0458A
+    root_uuid=02B4253F-29A4-404E-8972-1669D3B03C87
+    usr_guid=75250D76-8CC6-458E-BD66-BD47CC81A812
+    usr_uuid=7B42FFB0-B0E1-4395-B20B-C78F4A571648
     architecture="x86"
 elif [ "${machine}" = "aarch64" ] || [ "${machine}" = "aarch64_be" ] || [ "${machine}" = "armv8b" ] || [ "${machine}" = "armv8l" ]; then
-    root_guid=b921b045-1df0-41c3-af44-4c6f280d3fae
-    root_uuid=055d0227-53a6-4033-85c3-9a5973eff483
-    usr_guid=b0e01050-ee5f-4390-949a-9101b17104e9
-    usr_uuid=fce3c75e-d6a4-44c0-87f0-4c105183fb1f
+    root_guid=B921B045-1DF0-41C3-AF44-4C6F280D3FAE
+    root_uuid=055D0227-53A6-4033-85C3-9A5973EFF483
+    usr_guid=B0E01050-EE5F-4390-949A-9101B17104E9
+    usr_uuid=FCE3C75E-D6A4-44C0-87F0-4C105183FB1F
     architecture="arm64"
 elif [ "${machine}" = "arm" ]; then
-    root_guid=69dad710-2ce4-4e3c-b16c-21a1d49abed3
-    root_uuid=567da89e-8de2-4499-8d10-18f212dff034
-    usr_guid=7d0359a3-02b3-4f0a-865c-654403e70625
-    usr_uuid=71e93dc2-5073-42cb-8a84-a354e64d8966
+    root_guid=69DAD710-2CE4-4E3C-B16C-21A1D49ABED3
+    root_uuid=567DA89E-8DE2-4499-8D10-18F212DFF034
+    usr_guid=7D0359A3-02B3-4F0A-865C-654403E70625
+    usr_uuid=71E93DC2-5073-42CB-8A84-A354E64D8966
     architecture="arm"
 elif [ "${machine}" = "loongarch64" ]; then
-    root_guid=77055800-792c-4f94-b39a-98c91b762bb6
-    root_uuid=d8efc2d2-0133-41e4-bdcb-3b9f4cfddde8
-    usr_guid=e611c702-575c-4cbe-9a46-434fa0bf7e3f
-    usr_uuid=031ffa75-00bb-49b6-a70d-911d2d82a5b7
+    root_guid=77055800-792C-4F94-B39A-98C91B762BB6
+    root_uuid=D8EFC2D2-0133-41E4-BDCB-3B9F4CFDDDE8
+    usr_guid=E611C702-575C-4CBE-9A46-434FA0BF7E3F
+    usr_uuid=031FFA75-00BB-49B6-A70D-911D2D82A5B7
     architecture="loongarch64"
 elif [ "${machine}" = "ia64" ]; then
-    root_guid=993d8d3d-f80e-4225-855a-9daf8ed7ea97
-    root_uuid=dcf33449-0896-4ea9-bc24-7d58aeef522d
-    usr_guid=4301d2a6-4e3b-4b2a-bb94-9e0b2c4225ea
-    usr_uuid=bc2bcce7-80d6-449a-85cc-637424ce5241
+    root_guid=993D8D3D-F80E-4225-855A-9DAF8ED7EA97
+    root_uuid=DCF33449-0896-4EA9-BC24-7D58AEEF522D
+    usr_guid=4301D2A6-4E3B-4B2A-BB94-9E0B2C4225EA
+    usr_uuid=BC2BCCE7-80D6-449A-85CC-637424CE5241
     architecture="ia64"
 elif [ "${machine}" = "s390x" ]; then
-    root_guid=5eead9a9-fe09-4a1e-a1d7-520d00531306
-    root_uuid=7ebe0c85-e27e-48ec-b164-f4807606232e
-    usr_guid=8a4f5770-50aa-4ed3-874a-99b710db6fea
-    usr_uuid=51171d30-35cf-4a49-b8b5-9478b9b796a5
+    root_guid=5EEAD9A9-FE09-4A1E-A1D7-520D00531306
+    root_uuid=7EBE0C85-E27E-48EC-B164-F4807606232E
+    usr_guid=8A4F5770-50AA-4ED3-874A-99B710DB6FEA
+    usr_uuid=51171D30-35CF-4A49-B8B5-9478B9B796A5
     architecture="s390x"
 elif [ "${machine}" = "ppc64le" ]; then
-    root_guid=c31c45e6-3f39-412e-80fb-4809c4980599
-    root_uuid=061e67a1-092f-482f-8150-b525d50d6654
-    usr_guid=15bb03af-77e7-4d4a-b12b-c0d084f7491c
-    usr_uuid=c0d0823b-8040-4c7c-a629-026248e297fb
+    root_guid=C31C45E6-3F39-412E-80FB-4809C4980599
+    root_uuid=061E67A1-092F-482F-8150-B525D50D6654
+    usr_guid=15BB03AF-77E7-4D4A-B12B-C0D084F7491C
+    usr_uuid=C0D0823B-8040-4C7C-A629-026248E297FB
     architecture="ppc64-le"
 else
     echo "Unexpected uname -m: ${machine} in testsuite-58.sh, please fix me"
     exit 1
 fi
 
-rm -f /var/tmp/testsuite-58.img /var/tmp/testsuite-58.2.img /tmp/testsuite-58.dump
-mkdir -p /tmp/testsuite-58-defs/
+test_copy_blocks() {
+    local defs imgs output
 
-# First part: create a disk image and verify its in order
+    defs="$(mktemp --directory "/tmp/test-repart.XXXXXXXXXX")"
+    imgs="$(mktemp --directory "/var/tmp/test-repart.XXXXXXXXXX")"
+    # shellcheck disable=SC2064
+    trap "rm -rf '$defs' '$imgs'" RETURN
 
-cat >/tmp/testsuite-58-defs/esp.conf <<EOF
+    # First, create a disk image and verify its in order
+
+    cat >"$defs/esp.conf" <<EOF
 [Partition]
 Type=esp
 SizeMinBytes=10M
 Format=vfat
 EOF
 
-cat >/tmp/testsuite-58-defs/usr.conf <<EOF
+    cat >"$defs/usr.conf" <<EOF
 [Partition]
 Type=usr-${architecture}
 SizeMinBytes=10M
@@ -85,7 +95,7 @@ Format=ext4
 ReadOnly=yes
 EOF
 
-cat >/tmp/testsuite-58-defs/root.conf <<EOF
+    cat >"$defs/root.conf" <<EOF
 [Partition]
 Type=root-${architecture}
 SizeMinBytes=10M
@@ -93,148 +103,185 @@ Format=ext4
 MakeDirectories=/usr /efi
 EOF
 
-systemd-repart --definitions=/tmp/testsuite-58-defs/ \
-               --empty=create \
-               --size=auto \
-               --seed=750b6cd5c4ae4012a15e7be3c29e6a47 \
-               /var/tmp/testsuite-58.img
+    systemd-repart --definitions="$defs" \
+                   --empty=create \
+                   --size=auto \
+                   --seed="$seed" \
+                   "$imgs/zzz"
 
-sfdisk --dump /var/tmp/testsuite-58.img | tee /tmp/testsuite-58.dump
+    output=$(sfdisk --dump "$imgs/zzz")
 
-grep -qixF "/var/tmp/testsuite-58.img1 : start=        2048, size=       20480, type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, uuid=39107B09-615D-48FB-BA37-C663885FCE67, name=\"esp\"" /tmp/testsuite-58.dump
-grep -qixF "/var/tmp/testsuite-58.img2 : start=       22528, size=       20480, type=${root_guid}, uuid=${root_uuid}, name=\"root-${architecture}\", attrs=\"GUID:59\"" /tmp/testsuite-58.dump
-grep -qixF "/var/tmp/testsuite-58.img3 : start=       43008, size=       20480, type=${usr_guid}, uuid=${usr_uuid}, name=\"usr-${architecture}\", attrs=\"GUID:60\"" /tmp/testsuite-58.dump
+    assert_in "$imgs/zzz1 : start=        2048, size=       20480, type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, uuid=39107B09-615D-48FB-BA37-C663885FCE67, name=\"esp\"" "$output"
+    assert_in "$imgs/zzz2 : start=       22528, size=       20480, type=${root_guid}, uuid=${root_uuid}, name=\"root-${architecture}\", attrs=\"GUID:59\"" "$output"
+    assert_in "$imgs/zzz3 : start=       43008, size=       20480, type=${usr_guid}, uuid=${usr_uuid}, name=\"usr-${architecture}\", attrs=\"GUID:60\"" "$output"
 
-# Second part, duplicate it with CopyBlocks=auto
+    # Then, create another image with CopyBlocks=auto
 
-cat >/tmp/testsuite-58-defs/esp.conf <<EOF
+    cat >"$defs/esp.conf" <<EOF
 [Partition]
 Type=esp
 CopyBlocks=auto
 EOF
 
-cat >/tmp/testsuite-58-defs/usr.conf <<EOF
+    cat >"$defs/usr.conf" <<EOF
 [Partition]
 Type=usr-${architecture}
 ReadOnly=yes
 CopyBlocks=auto
 EOF
 
-cat >/tmp/testsuite-58-defs/root.conf <<EOF
+    cat >"$defs/root.conf" <<EOF
 [Partition]
 Type=root-${architecture}
 CopyBlocks=auto
 EOF
 
-systemd-repart --definitions=/tmp/testsuite-58-defs/ \
-               --empty=create \
-               --size=auto \
-               --seed=750b6cd5c4ae4012a15e7be3c29e6a47 \
-               --image=/var/tmp/testsuite-58.img \
-               /var/tmp/testsuite-58.2.img
+    systemd-repart --definitions="$defs" \
+                   --empty=create \
+                   --size=auto \
+                   --seed="$seed" \
+                   --image="$imgs/zzz" \
+                   "$imgs/yyy"
 
-cmp /var/tmp/testsuite-58.img /var/tmp/testsuite-58.2.img
+    cmp "$imgs/zzz" "$imgs/yyy"
+}
 
-rm /var/tmp/testsuite-58.img /var/tmp/testsuite-58.2.img /tmp/testsuite-58.dump
-rm -r /tmp/testsuite-58-defs/
+test_unaligned_partition() {
+    local defs imgs output
 
-# Third part: operate on an an image with unaligned partition, to see if that works.
+    defs="$(mktemp --directory "/tmp/test-repart.XXXXXXXXXX")"
+    imgs="$(mktemp --directory "/var/tmp/test-repart.XXXXXXXXXX")"
+    # shellcheck disable=SC2064
+    trap "rm -rf '$defs' '$imgs'" RETURN
 
-rm -f /var/tmp/testsuite-58.3.img /tmp/testsuite-58-3.dump
-mkdir -p /tmp/testsuite-58.3-defs/
+    # Operate on an image with unaligned partition.
 
-cat >/tmp/testsuite-58.3-defs/root.conf <<EOF
+    cat >"$defs/root.conf" <<EOF
 [Partition]
 Type=root-${architecture}
 EOF
 
-truncate -s 10g /var/tmp/testsuite-58.3.img
-sfdisk /var/tmp/testsuite-58.3.img <<EOF
+    truncate -s 10g "$imgs/unaligned"
+    sfdisk "$imgs/unaligned" <<EOF
 label: gpt
 
 start=2048, size=69044
 start=71092, size=3591848
 EOF
 
-systemd-repart --definitions=/tmp/testsuite-58.3-defs/ \
-               --seed=750b6cd5c4ae4012a15e7be3c29e6a47 \
-               --dry-run=no \
-               /var/tmp/testsuite-58.3.img
+    systemd-repart --definitions="$defs" \
+                   --seed="$seed" \
+                   --dry-run=no \
+                   "$imgs/unaligned"
 
-sfdisk --dump /var/tmp/testsuite-58.3.img | tee /tmp/testsuite-58.3.dump
+    output=$(sfdisk --dump "$imgs/unaligned")
 
-grep -qF '/var/tmp/testsuite-58.3.img1 : start=        2048, size=       69044,' /tmp/testsuite-58.3.dump
-grep -qF '/var/tmp/testsuite-58.3.img2 : start=       71092, size=     3591848,' /tmp/testsuite-58.3.dump
-grep -qixF "/var/tmp/testsuite-58.3.img3 : start=     3662944, size=    17308536, type=${root_guid}, uuid=${root_uuid}, name=\"root-${architecture}\", attrs=\"GUID:59\"" /tmp/testsuite-58.3.dump
+    assert_in "$imgs/unaligned1 : start=        2048, size=       69044," "$output"
+    assert_in "$imgs/unaligned2 : start=       71092, size=     3591848," "$output"
+    assert_in "$imgs/unaligned3 : start=     3662944, size=    17308536, type=${root_guid}, uuid=${root_uuid}, name=\"root-${architecture}\", attrs=\"GUID:59\"" "$output"
+}
 
-rm /var/tmp/testsuite-58.3.img /tmp/testsuite-58.3.dump
-rm -r /tmp/testsuite-58.3-defs/
+test_issue_21817() {
+    local defs imgs output
 
-# testcase for #21817
-mkdir -p /tmp/testsuite-58-issue-21817-defs/
-truncate -s 100m /var/tmp/testsuite-58-issue-21817.img
-sfdisk /var/tmp/testsuite-58-issue-21817.img <<EOF
+    # testcase for #21817
+
+    defs="$(mktemp --directory "/tmp/test-repart.XXXXXXXXXX")"
+    imgs="$(mktemp --directory "/var/tmp/test-repart.XXXXXXXXXX")"
+    # shellcheck disable=SC2064
+    trap "rm -rf '$defs' '$imgs'" RETURN
+
+    cat >"$defs/test.conf" <<EOF
+[Partition]
+Type=root
+EOF
+
+    truncate -s 100m "$imgs/21817.img"
+    sfdisk "$imgs/21817.img" <<EOF
 label: gpt
 
 size=50M, type=${root_guid}
 ,
 EOF
-cat >/tmp/testsuite-58-issue-21817-defs/test.conf <<EOF
-[Partition]
-Type=root
-EOF
-systemd-repart --pretty=yes --definitions /tmp/testsuite-58-issue-21817-defs/ --dry-run=no /var/tmp/testsuite-58-issue-21817.img
-sfdisk --dump /var/tmp/testsuite-58-issue-21817.img | tee /tmp/testsuite-58-issue-21817.dump
 
-grep -qiF "/var/tmp/testsuite-58-issue-21817.img1 : start=        2048, size=      102400, type=${root_guid}," /tmp/testsuite-58-issue-21817.dump
-# Accept both unpadded (pre-v2.38 util-linux) and padded (v2.38+ util-linux) sizes
-grep -qE "/var/tmp/testsuite-58-issue-21817.img2 : start=      104448, size=      (100319| 98304)," /tmp/testsuite-58-issue-21817.dump
+    systemd-repart --pretty=yes \
+                   --definitions "$imgs" \
+                   --seed="$seed" \
+                   --dry-run=no \
+                   "$imgs/21817.img"
 
-rm /var/tmp/testsuite-58-issue-21817.img /tmp/testsuite-58-issue-21817.dump
-rm -r /tmp/testsuite-58-issue-21817-defs/
+    output=$(sfdisk --dump "$imgs/21817.img")
 
-testsector()
-{
-    echo "Running sector test with sector size $1..."
+    assert_in "$imgs/21817.img1 : start=        2048, size=      102400, type=${root_guid}," "$output"
+    # Accept both unpadded (pre-v2.38 util-linux) and padded (v2.38+ util-linux) sizes
+    assert_in "$imgs/21817.img2 : start=      104448, size=      (100319| 98304)," "$output"
+}
 
-    mkdir -p /tmp/testsuite-58-sector
-    cat > /tmp/testsuite-58-sector/a.conf <<EOF
+test_sector() {
+    local defs imgs output loop
+    local start size ratio
+    local sector="${1?}"
+
+    defs="$(mktemp --directory "/tmp/test-repart.XXXXXXXXXX")"
+    imgs="$(mktemp --directory "/var/tmp/test-repart.XXXXXXXXXX")"
+    # shellcheck disable=SC2064
+    trap "rm -rf '$defs' '$imgs'" RETURN
+
+    cat > "$defs/a.conf" <<EOF
 [Partition]
 Type=root
 SizeMaxBytes=15M
 SizeMinBytes=15M
 EOF
-    cat > /tmp/testsuite-58-sector/b.conf <<EOF
+    cat > "$defs/b.conf" <<EOF
 [Partition]
 Type=linux-generic
 Weight=250
 EOF
 
-    cat > /tmp/testsuite-58-sector/c.conf <<EOF
+    cat > "$defs/c.conf" <<EOF
 [Partition]
 Type=linux-generic
 Weight=750
 EOF
 
-    truncate -s 100m "/tmp/testsuite-58-sector-$1.img"
-    LOOP=$(losetup -b "$1" -P --show -f "/tmp/testsuite-58-sector-$1.img" )
-    udevadm wait --timeout 60 --settle "${LOOP:?}"
-    systemd-repart --pretty=yes --definitions=/tmp/testsuite-58-sector/ --seed=750b6cd5c4ae4012a15e7be3c29e6a47 --empty=require --dry-run=no "$LOOP"
-    rm -rf /tmp/testsuite-58-sector
-    sfdisk --verify "$LOOP"
-    sfdisk --dump "$LOOP"
-    losetup -d "$LOOP"
+    truncate -s 100m "$imgs/$sector.img"
+    loop=$(losetup -b "$sector" -P --show -f "$imgs/$sector.img" )
+    udevadm wait --timeout 60 --settle "${loop:?}"
+    systemd-repart --pretty=yes \
+                   --definitions="$defs" \
+                   --seed="$seed" \
+                   --empty=require \
+                   --dry-run=no \
+                   "$loop"
 
-    rm "/tmp/testsuite-58-sector-$1.img"
+    sfdisk --verify "$loop"
+    output=$(sfdisk --dump "$loop")
+    losetup -d "$loop"
+
+    ratio=$(( sector / 512 ))
+    start=$(( 2048 / ratio ))
+    size=$(( 30720 / ratio ))
+    assert_in "${loop}p1 : start= *${start}, size= *${size}, type=${root_guid}, uuid=${root_uuid}, name=\"root-${architecture}\", attrs=\"GUID:59\"" "$output"
+    start=$(( start + size ))
+    size=$(( 42992 / ratio ))
+    assert_in "${loop}p2 : start= *${start}, size= *${size}, type=0FC63DAF-8483-4772-8E79-3D69D8477DE4, uuid=DF71F5E3-080A-4D16-824B-18591B881380, name=\"linux-generic\"" "$output"
+    start=$(( start + size ))
+    size=$(( 129000 / ratio ))
+    assert_in "${loop}p3 : start= *${start}, size= *${size}, type=0FC63DAF-8483-4772-8E79-3D69D8477DE4, uuid=DB081670-07AE-48CA-9F5E-813D5E40B976, name=\"linux-generic-2\"" "$output"
 }
 
+test_copy_blocks
+test_unaligned_partition
+test_issue_21817
+
 # Valid block sizes on the Linux block layer are >= 512 and <= PAGE_SIZE, and
 # must be powers of 2. Which leaves exactly four different ones to test on
 # typical hardware
-testsector 512
-testsector 1024
-testsector 2048
-testsector 4096
+test_sector 512
+test_sector 1024
+test_sector 2048
+test_sector 4096
 
 echo OK >/testok