diff --git a/tools/xen/functions b/tools/xen/functions
new file mode 100644
index 0000000..5b4a661
--- /dev/null
+++ b/tools/xen/functions
@@ -0,0 +1,55 @@
+#!/bin/bash
+
+function xapi_plugin_location {
+    for PLUGIN_DIR in "/etc/xapi.d/plugins/" "/usr/lib/xcp/plugins/"
+    do
+        if [ -d $PLUGIN_DIR ]
+        then
+            echo $PLUGIN_DIR
+            return 0
+        fi
+    done
+    return 1
+}
+
+function zip_snapshot_location {
+    echo $1 | sed "s:\.git$::;s:$:/zipball/$2:g"
+}
+
+function create_directory_for_kernels {
+    mkdir -p "/boot/guest"
+}
+
+function extract_remote_zipball {
+    local ZIPBALL_URL=$1
+
+    local LOCAL_ZIPBALL=$(mktemp)
+    local EXTRACTED_FILES=$(mktemp -d)
+
+    (
+        wget -nv $ZIPBALL_URL -O $LOCAL_ZIPBALL --no-check-certificate
+        unzip -q -o $LOCAL_ZIPBALL -d $EXTRACTED_FILES
+        rm -f $LOCAL_ZIPBALL
+    ) >&2
+
+    echo "$EXTRACTED_FILES"
+}
+
+function find_xapi_plugins_dir {
+    find $1 -path '*/xapi.d/plugins' -type d -print
+}
+
+function install_xapi_plugins_from_zipball {
+    local XAPI_PLUGIN_DIR
+    local EXTRACTED_FILES
+    local EXTRACTED_PLUGINS_DIR
+
+    XAPI_PLUGIN_DIR=$(xapi_plugin_location)
+
+    EXTRACTED_FILES=$(extract_remote_zipball $1)
+    EXTRACTED_PLUGINS_DIR=$(find_xapi_plugins_dir $EXTRACTED_FILES)
+
+    cp -pr $EXTRACTED_PLUGINS_DIR/* $XAPI_PLUGIN_DIR
+    rm -rf $EXTRACTED_FILES
+    chmod a+x ${XAPI_PLUGIN_DIR}*
+}
diff --git a/tools/xen/install_os_domU.sh b/tools/xen/install_os_domU.sh
index 0c0e1e2..7c3b839 100755
--- a/tools/xen/install_os_domU.sh
+++ b/tools/xen/install_os_domU.sh
@@ -28,6 +28,9 @@
 # Include onexit commands
 . $THIS_DIR/scripts/on_exit.sh
 
+# xapi functions
+. $THIS_DIR/functions
+
 
 #
 # Get Settings
@@ -43,48 +46,26 @@
   xe "$cmd" --minimal "$@"
 }
 
-
 #
 # Prepare Dom0
 # including installing XenAPI plugins
 #
 
 cd $THIS_DIR
-if [ -f ./master ]
-then
-    rm -rf ./master
-    rm -rf ./nova
-fi
 
-# get nova
-NOVA_ZIPBALL_URL=${NOVA_ZIPBALL_URL:-$(echo $NOVA_REPO | sed "s:\.git$::;s:$:/zipball/$NOVA_BRANCH:g")}
-wget -nv $NOVA_ZIPBALL_URL -O nova-zipball --no-check-certificate
-unzip -q -o nova-zipball  -d ./nova
+# Install plugins
 
-# install xapi plugins
-XAPI_PLUGIN_DIR=/etc/xapi.d/plugins/
-if [ ! -d $XAPI_PLUGIN_DIR ]; then
-    # the following is needed when using xcp-xapi
-    XAPI_PLUGIN_DIR=/usr/lib/xcp/plugins/
-fi
-cp -pr ./nova/*/plugins/xenserver/xenapi/etc/xapi.d/plugins/* $XAPI_PLUGIN_DIR
+## Nova plugins
+NOVA_ZIPBALL_URL=${NOVA_ZIPBALL_URL:-$(zip_snapshot_location $NOVA_REPO $NOVA_BRANCH)}
+install_xapi_plugins_from_zipball $NOVA_ZIPBALL_URL
 
-# Install the netwrap xapi plugin to support agent control of dom0 networking
+## Install the netwrap xapi plugin to support agent control of dom0 networking
 if [[ "$ENABLED_SERVICES" =~ "q-agt" && "$Q_PLUGIN" = "openvswitch" ]]; then
-    if [ -f ./quantum ]; then
-        rm -rf ./quantum
-    fi
-    # get quantum
-    QUANTUM_ZIPBALL_URL=${QUANTUM_ZIPBALL_URL:-$(echo $QUANTUM_REPO | sed "s:\.git$::;s:$:/zipball/$QUANTUM_BRANCH:g")}
-    wget -nv $QUANTUM_ZIPBALL_URL -O quantum-zipball --no-check-certificate
-    unzip -q -o quantum-zipball  -d ./quantum
-    cp -pr ./quantum/*/quantum/plugins/openvswitch/agent/xenapi/etc/xapi.d/plugins/* $XAPI_PLUGIN_DIR
+    QUANTUM_ZIPBALL_URL=${QUANTUM_ZIPBALL_URL:-$(zip_snapshot_location $QUANTUM_REPO $QUANTUM_BRANCH)}
+    install_xapi_plugins_from_zipball $QUANTUM_ZIPBALL_URL
 fi
 
-chmod a+x ${XAPI_PLUGIN_DIR}*
-
-mkdir -p /boot/guest
-
+create_directory_for_kernels
 
 #
 # Configure Networking
diff --git a/tools/xen/mocks b/tools/xen/mocks
new file mode 100644
index 0000000..b006558
--- /dev/null
+++ b/tools/xen/mocks
@@ -0,0 +1,59 @@
+#!/bin/bash
+
+test ! -e "$LIST_OF_ACTIONS" && {
+    echo "Mocking is not set up properly."
+    echo "LIST_OF_ACTIONS should point to an existing file."
+    exit 1
+}
+
+test ! -e "$LIST_OF_DIRECTORIES" && {
+    echo "Mocking is not set up properly."
+    echo "LIST_OF_DIRECTORIES should point to an existing file."
+    exit 1
+}
+
+function mktemp {
+    if test "${1:-}" = "-d";
+    then
+        echo "tempdir"
+    else
+        echo "tempfile"
+    fi
+}
+
+function wget {
+    echo "wget $@" >> $LIST_OF_ACTIONS
+}
+
+function mkdir {
+    if test "${1:-}" = "-p";
+    then
+        echo "$2" >> $LIST_OF_DIRECTORIES
+    fi
+}
+
+function unzip {
+    echo "Random rubbish from unzip"
+    echo "unzip $@" >> $LIST_OF_ACTIONS
+}
+
+function rm {
+    echo "rm $@" >> $LIST_OF_ACTIONS
+}
+
+function [ {
+    if test "${1:-}" = "-d";
+    then
+        echo "[ $@" >> $LIST_OF_ACTIONS
+        for directory in $(cat $LIST_OF_DIRECTORIES)
+        do
+            if test "$directory" = "$2"
+            then
+                return 0
+            fi
+        done
+        return 1
+    fi
+    echo "Mock test does not implement the requested function"
+    exit 1
+}
diff --git a/tools/xen/test_functions.sh b/tools/xen/test_functions.sh
new file mode 100755
index 0000000..6817ec3
--- /dev/null
+++ b/tools/xen/test_functions.sh
@@ -0,0 +1,134 @@
+#!/bin/bash
+
+# Tests for functions.
+#
+# The tests are sourcing the mocks file to mock out various functions. The
+# mocking-out always happens in a sub-shell, thus it does not have impact on
+# the functions defined here.
+
+# To run the tests, please run:
+#
+# ./test_functions.sh run_tests
+#
+# To only print out the discovered test functions, run:
+#
+# ./test_functions.sh
+
+. functions
+
+# Setup
+function before_each_test {
+    LIST_OF_DIRECTORIES=$(mktemp)
+    truncate -s 0 $LIST_OF_DIRECTORIES
+
+    LIST_OF_ACTIONS=$(mktemp)
+    truncate -s 0 $LIST_OF_ACTIONS
+}
+
+# Teardown
+function after_each_test {
+    rm -f $LIST_OF_DIRECTORIES
+    rm -f $LIST_OF_ACTIONS
+}
+
+# Helpers
+function given_directory_exists {
+    echo "$1" >> $LIST_OF_DIRECTORIES
+}
+
+function assert_directory_exists {
+    grep "$1" $LIST_OF_DIRECTORIES
+}
+
+function assert_previous_command_failed {
+    [ "$?" != "0" ] || exit 1
+}
+
+# Tests
+function test_plugin_directory_on_xenserver {
+    given_directory_exists "/etc/xapi.d/plugins/"
+
+    PLUGDIR=$(. mocks && xapi_plugin_location)
+
+    [ "/etc/xapi.d/plugins/" = "$PLUGDIR" ]
+}
+
+function test_plugin_directory_on_xcp {
+    given_directory_exists "/usr/lib/xcp/plugins/"
+
+    PLUGDIR=$(. mocks && xapi_plugin_location)
+
+    [ "/usr/lib/xcp/plugins/" = "$PLUGDIR" ]
+}
+
+function test_no_plugin_directory_found {
+    set +e
+
+    local IGNORE
+    IGNORE=$(. mocks && xapi_plugin_location)
+
+    assert_previous_command_failed
+
+    grep "[ -d /etc/xapi.d/plugins/ ]" $LIST_OF_ACTIONS
+    grep "[ -d /usr/lib/xcp/plugins/ ]" $LIST_OF_ACTIONS
+}
+
+function test_zip_snapshot_location {
+    diff \
+    <(zip_snapshot_location "https://github.com/openstack/nova.git" "master") \
+    <(echo "https://github.com/openstack/nova/zipball/master")
+}
+
+function test_create_directory_for_kernels {
+    (. mocks && create_directory_for_kernels)
+
+    assert_directory_exists "/boot/guest"
+}
+
+function test_extract_remote_zipball {
+    local RESULT=$(. mocks && extract_remote_zipball "someurl")
+
+    diff <(cat $LIST_OF_ACTIONS) - << EOF
+wget -nv someurl -O tempfile --no-check-certificate
+unzip -q -o tempfile -d tempdir
+rm -f tempfile
+EOF
+
+    [ "$RESULT" = "tempdir" ]
+}
+
+function test_find_nova_plugins {
+    local tmpdir=$(mktemp -d)
+
+    mkdir -p "$tmpdir/blah/blah/u/xapi.d/plugins"
+
+    [ "$tmpdir/blah/blah/u/xapi.d/plugins" = $(find_xapi_plugins_dir $tmpdir) ]
+
+    rm -rf $tmpdir
+}
+
+# Test runner
+[ "$1" = "" ] && {
+    grep -e "^function *test_" $0 | cut -d" " -f2
+}
+
+[ "$1" = "run_tests" ] && {
+    for testname in $($0)
+    do
+        echo "$testname"
+        before_each_test
+        (
+            set -eux
+            $testname
+        )
+        if [ "$?" != "0" ]
+        then
+            echo "FAIL"
+            exit 1
+        else
+            echo "PASS"
+        fi
+
+        after_each_test
+    done
+}