diff --git a/bin/dib-run-parts b/bin/dib-run-parts
index 575e6fd..78580fb 100755
--- a/bin/dib-run-parts
+++ b/bin/dib-run-parts
@@ -34,8 +34,21 @@ usage() {
     exit 1
 } >&2
 
+
+output_prefix() {
+    printf "%s %s " "${name}" "$(date)" >&2
+}
+
 output () {
-    echo $name $(date) $* >&2
+    output_prefix
+    echo $* >&2
+}
+
+output_printf () {
+    local FORMAT="$1"
+    shift
+    output_prefix
+    printf "${FORMAT}" $@ >&2
 }
 
 if [ $# -lt 1 ] ; then
@@ -91,22 +104,22 @@ for target in $targets ; do
     output "$target completed"
 done
 
-echo "----------------------- PROFILING -----------------------"
-echo ""
-echo "Target: $(basename $target_dir)"
-echo ""
-printf "%-40s %9s\n" Script Seconds
-printf "%-40s %9s\n" --------------------------------------- ----------
-echo ""
+output "----------------------- PROFILING -----------------------"
+output ""
+output "Target: $(basename $target_dir)"
+output ""
+output_printf "%-40s %9s\n" Script Seconds
+output_printf "%-40s %9s\n" --------------------------------------- ----------
+output ""
 pushd $PROFILE_DIR > /dev/null
 for target in $(find . -name 'start_*' -printf '%f\n' | env LC_ALL=C sort -n) ; do
     stop_file=stop_${target##start_}
     start_seconds=$(cat $target)
     stop_seconds=$(cat $stop_file)
     duration=$(echo - | awk "{ print $stop_seconds - $start_seconds }")
-    LC_NUMERIC=C LC_ALL=C printf "%-40s %10.3f\n" ${target##start_} $duration
+    LC_NUMERIC=C LC_ALL=C output_printf "%-40s %10.3f\n" ${target##start_} $duration
 done
 popd > /dev/null
 rm -rf $PROFILE_DIR
-echo ""
-echo "--------------------- END PROFILING ---------------------"
+output ""
+output "--------------------- END PROFILING ---------------------"
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
new file mode 100755
index 0000000..24f9146
--- /dev/null
+++ b/tests/run_tests.sh
@@ -0,0 +1,16 @@
+#!/bin/bash
+#
+# Runs all test cases in this directory
+#
+
+set -ue
+set -o pipefail
+
+TESTS_BASE_DIR=$(cd $(dirname "$0") && pwd)
+
+for tc in ${TESTS_BASE_DIR}/tc??.sh; do
+    echo "--- Running ${tc} ---"
+    ${tc}
+done
+
+echo "--- TESTS COMPLETE ---"
diff --git a/tests/tc01.sh b/tests/tc01.sh
new file mode 100755
index 0000000..19948d4
--- /dev/null
+++ b/tests/tc01.sh
@@ -0,0 +1,39 @@
+#!/bin/bash
+#
+# Runs dib-run-parts on an empty directory.
+#
+
+set -ue
+set -o pipefail
+set -x
+
+TESTS_BASE_DIR=$(cd $(dirname "$0") && pwd)
+
+DRP_BIN=${TESTS_BASE_DIR}/../bin/dib-run-parts
+
+TEST_EXEC_DIR=${TESTS_BASE_DIR}/tc01/td
+
+mkdir -p ${TEST_EXEC_DIR}
+rval=0
+
+RES=$(${DRP_BIN} --list ${TEST_EXEC_DIR})
+if test $? -ne 0; then
+    echo "*** FAILED: --list of empty dir failed"
+    rval=1
+fi
+if test -n "${RES}"; then
+    echo "*** FAILED: --list of empty dir not empty"
+    rval=1
+fi
+
+RES=$(${DRP_BIN} ${TEST_EXEC_DIR} 2>/dev/null)
+if test $? -ne 0; then
+    echo "*** FAILED: dib-run-parts on empty dir failed"
+    rval=1
+fi
+if test -n "${RES}"; then
+    echo "*** FAILED: dib-run-parts on empty dir not empty"
+    rval=1
+fi
+
+exit ${rval}
diff --git a/tests/tc02.sh b/tests/tc02.sh
new file mode 100755
index 0000000..f33f355
--- /dev/null
+++ b/tests/tc02.sh
@@ -0,0 +1,46 @@
+#!/bin/bash
+#
+# Runs dib-run-parts on directory containing some scripts.
+#
+
+set -ue
+set -o pipefail
+set -x
+
+TESTS_BASE_DIR=$(cd $(dirname "$0") && pwd)
+
+DRP_BIN=${TESTS_BASE_DIR}/../bin/dib-run-parts
+
+TEST_EXEC_DIR=${TESTS_BASE_DIR}/tc02/td
+
+rval=0
+
+RES=$(${DRP_BIN} --list ${TEST_EXEC_DIR})
+if test $? -ne 0; then
+    echo "*** FAILED: --list failed"
+    rval=1
+fi
+
+EXPECTED="${TESTS_BASE_DIR}/tc02/td/call_me_1
+${TESTS_BASE_DIR}/tc02/td/call_me_2"
+
+if test "${EXPECTED}" != "${RES}"; then
+    echo "*** FAILED: --list returns incorrect result"
+    rval=1
+fi
+
+RES=$(${DRP_BIN} ${TEST_EXEC_DIR} 2>/dev/null)
+if test $? -ne 0; then
+    echo "*** FAILED: dib-run-parts on empty dir failed"
+    rval=1
+fi
+
+EXPECTED="call_me_1 called
+call_me_2 called"
+
+if test "${EXPECTED}" != "${RES}"; then
+    echo "*** FAILED: dib-run-parts returns incorrect result"
+    rval=1
+fi
+
+exit ${rval}
diff --git a/tests/tc02/td/call_me_1 b/tests/tc02/td/call_me_1
new file mode 100755
index 0000000..4e3b6a0
--- /dev/null
+++ b/tests/tc02/td/call_me_1
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+echo "call_me_1 called"
diff --git a/tests/tc02/td/call_me_2 b/tests/tc02/td/call_me_2
new file mode 100755
index 0000000..d96423d
--- /dev/null
+++ b/tests/tc02/td/call_me_2
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+echo "call_me_2 called"
diff --git a/tests/tc03.sh b/tests/tc03.sh
new file mode 100755
index 0000000..605f88c
--- /dev/null
+++ b/tests/tc03.sh
@@ -0,0 +1,33 @@
+#!/bin/bash
+#
+# Runs dib-run-parts on directory containing some scripts
+# and using the environment directory.
+#
+
+set -ue
+set -o pipefail
+set -x
+
+TESTS_BASE_DIR=$(dirname $0)
+
+DRP_BIN=${TESTS_BASE_DIR}/../bin/dib-run-parts
+
+TEST_EXEC_DIR=${TESTS_BASE_DIR}/tc03/td
+
+rval=0
+
+RES=$(${DRP_BIN} ${TEST_EXEC_DIR} 2>/dev/null)
+if test $? -ne 0; then
+    echo "*** FAILED: dib-run-parts failed"
+    rval=1
+fi
+
+EXPECTED="call_me_1 called [Some thing]
+call_me_2 called [Other thing]"
+
+if test "${EXPECTED}" != "${RES}"; then
+    echo "*** FAILED: dib-run-parts returns incorrect result"
+    rval=1
+fi
+
+exit ${rval}
diff --git a/tests/tc03/environment.d/set_var.bash b/tests/tc03/environment.d/set_var.bash
new file mode 100644
index 0000000..d9dc4ac
--- /dev/null
+++ b/tests/tc03/environment.d/set_var.bash
@@ -0,0 +1,5 @@
+#!/bin/bash
+
+export CM1="Some thing"
+export CM2="Other thing"
+
diff --git a/tests/tc03/td/call_me_1 b/tests/tc03/td/call_me_1
new file mode 100755
index 0000000..11a4850
--- /dev/null
+++ b/tests/tc03/td/call_me_1
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+echo "call_me_1 called [${CM1}]"
diff --git a/tests/tc03/td/call_me_2 b/tests/tc03/td/call_me_2
new file mode 100755
index 0000000..db5dec8
--- /dev/null
+++ b/tests/tc03/td/call_me_2
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+echo "call_me_2 called [${CM2}]"
diff --git a/tox.ini b/tox.ini
index 7d57b47..e8538f7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,3 +5,7 @@ skipsdist = True
 [testenv:venv]
 commands = {posargs}
 
+[testenv:func]
+changedir={toxinidir}/tests
+envdir = {toxworkdir}/venv
+commands = ./run_tests.sh {posargs}