+# usage: corrupt_midx_and_verify <pos> <data> <objdir> <string>
+corrupt_midx_and_verify() {
+ POS=$1 &&
+ DATA="${2:-\0}" &&
+ OBJDIR=$3 &&
+ GREPSTR="$4" &&
+ FILE=$OBJDIR/pack/multi-pack-index &&
+ chmod a+w $FILE &&
+ test_when_finished mv midx-backup $FILE &&
+ cp $FILE midx-backup &&
+ printf "$DATA" | dd of="$FILE" bs=1 seek="$POS" conv=notrunc &&
+ test_must_fail git multi-pack-index verify --object-dir=$OBJDIR 2>test_err &&
+ grep -v "^+" test_err >err &&
+ test_i18ngrep "$GREPSTR" err
+}
+
+test_expect_success 'verify bad signature' '
+ corrupt_midx_and_verify 0 "\00" $objdir \
+ "multi-pack-index signature"
+'
+
+MIDX_BYTE_VERSION=4
+MIDX_BYTE_OID_VERSION=5
+MIDX_BYTE_CHUNK_COUNT=6
+
+test_expect_success 'verify bad version' '
+ corrupt_midx_and_verify $MIDX_BYTE_VERSION "\00" $objdir \
+ "multi-pack-index version"
+'
+
+test_expect_success 'verify bad OID version' '
+ corrupt_midx_and_verify $MIDX_BYTE_OID_VERSION "\02" $objdir \
+ "hash version"
+'
+
+test_expect_success 'verify truncated chunk count' '
+ corrupt_midx_and_verify $MIDX_BYTE_CHUNK_COUNT "\01" $objdir \
+ "missing required"
+'
+
+test_expect_success 'verify extended chunk count' '
+ corrupt_midx_and_verify $MIDX_BYTE_CHUNK_COUNT "\07" $objdir \
+ "terminating multi-pack-index chunk id appears earlier than expected"
+'
+