Added test for "--sync"

tests/Modifiers_-_--sync.sh

@@ -0,0 +1,45 @@
+#!/bin/sh
+#
+# Transfer a large chunk of data with "--sync" and check data correctness
+# afterwards, both with and without rate limits.  Note that this doesn't
+# check that fdatasync() is actually being called, it just checks that data
+# is not being corrupted.
+
+# Dummy assignments for "shellcheck".
+testSubject="${testSubject:-false}"; workFile1="${workFile1:-.tmp1}"; workFile2="${workFile2:-.tmp2}"
+
+# generate some data
+dd if=/dev/urandom of="${workFile1}" bs=1024 count=2560 2>/dev/null
+
+inputChecksum=$(cksum "${workFile1}" | awk '{print $1}')
+
+# read through pv and test afterwards
+"${testSubject}" -q "${workFile1}" > "${workFile2}"
+outputChecksum=$(cksum "${workFile2}" | awk '{print $1}')
+
+if ! test "${inputChecksum}" = "${outputChecksum}"; then
+	echo "checksum mismatched even without \"--sync\""
+	exit 1
+fi
+
+# Same again but with "--sync"
+
+"${testSubject}" -Y -q "${workFile1}" > "${workFile2}"
+outputChecksum=$(cksum "${workFile2}" | awk '{print $1}')
+if ! test "${inputChecksum}" = "${outputChecksum}"; then
+	echo "checksum mismatched with \"--sync\""
+	exit 1
+fi
+
+# Now with "--sync" and "--rate-limit"
+
+"${testSubject}" -Y -L 800K -q "${workFile1}" > "${workFile2}"
+outputChecksum=$(cksum "${workFile2}" | awk '{print $1}')
+if ! test "${inputChecksum}" = "${outputChecksum}"; then
+	echo "checksum mismatched with \"--sync\" + \"--rate-limit\""
+	exit 1
+fi
+
+exit 0
+
+# EOF