update regression tests to check DXT

* mpi-io-test case now also checks that the DXT parser can handle
  a log file with no DXT data
* a new mpi-io-test was added to run with DXT tracing enabled
  to ensure DXT and it's parser are both functioning properly

darshan-test/regression/test-cases/mpi-io-test-dxt.sh

+#!/bin/bash
+
+PROG=mpi-io-test
+
+# set log file path; remove previous log if present
+export DARSHAN_LOGFILE=$DARSHAN_TMP/${PROG}-dxt.darshan
+rm -f ${DARSHAN_LOGFILE}
+
+# compile
+$DARSHAN_CC $DARSHAN_TESTDIR/test-cases/src/${PROG}.c -o $DARSHAN_TMP/${PROG}
+if [ $? -ne 0 ]; then
+    echo "Error: failed to compile ${PROG}" 1>&2
+    exit 1
+fi
+
+# enable dxt tracing
+export DXT_ENABLE_IO_TRACE=
+
+# execute
+$DARSHAN_RUNJOB $DARSHAN_TMP/${PROG} -f $DARSHAN_TMP/${PROG}.tmp.dat
+if [ $? -ne 0 ]; then
+    echo "Error: failed to execute ${PROG}" 1>&2
+    exit 1
+fi
+
+# parse log
+$DARSHAN_PATH/bin/darshan-dxt-parser $DARSHAN_LOGFILE > $DARSHAN_TMP/${PROG}.darshan.txt
+if [ $? -ne 0 ]; then
+    echo "Error: failed to parse ${DARSHAN_LOGFILE}" 1>&2
+    exit 1
+fi
+
+# TODO: check results
+
+# also, ensure that darshan-parser doesn't complain if given a log file that
+# has DXT data present
+$DARSHAN_PATH/bin/darshan-parser $DARSHAN_LOGFILE > /dev/null
+if [ $? -ne 0 ]; then
+    echo "Error: darshan-parser failed to handle ${DARSHAN_LOGFILE}" 1>&2
+    exit 1
+fi
+
+unset DXT_ENABLE_IO_TRACE
+
+exit 0

darshan-test/regression/test-cases/mpi-io-test.sh

@@ -40,4 +40,12 @@ if [ ! "$MPI_OPENS" -gt 0 ]; then
     exit 1
 fi
 
+# also, ensure that darshan-dxt-parser doesn't complain if given a log file that
+# does not have DXT data present
+$DARSHAN_PATH/bin/darshan-dxt-parser $DARSHAN_LOGFILE > /dev/null
+if [ $? -ne 0 ]; then
+    echo "Error: darshan-dxt-parser failed to handle ${DARSHAN_LOGFILE}" 1>&2
+    exit 1
+fi
+
 exit 0