D-Bus testing: add 'setupFiles' function in DBusUtil

The function 'setupFiles' is used to copy reference directory
trees from 'test/test-dbus' to 'xdg_root(./test-dbus)'. It
won't do copy unless own_xdg is enabled. Otherwise, user's
directories might be polluted.

This function is for those unit tests which are
hard(or impossbile) to do comparisons. To solve this
problem, we can create reference files in 'test/test-dbus'
and copy them to 'xdg_root' and compare expected results
with values returned from DBus server.

Currently 4 sub-directories are copied, but
maybe with different names, mappings are:
 test/test-dbus               ./test-dbus
    sync4j                       .sync4j
    data                         data
    config                       config
    cache                        cache

test/test-dbus.py

@@ -30,6 +30,8 @@ import heapq
 import dbus
 from dbus.mainloop.glib import DBusGMainLoop
 import gobject
+import sys
+
 # introduced in python-gobject 2.16, not available
 # on all Linux distros => make it optional
 try:
@@ -244,6 +246,9 @@ class DBusUtil(Timeout):
         kill = subprocess.Popen("sh -c 'killall -9 syncevo-dbus-server dbus-monitor >/dev/null 2>&1'", shell=True)
         kill.communicate()
 
+        """own_xdg is saved in self for we use this flag to check whether
+        copying reference directory tree."""
+        self.own_xdg = own_xdg
         env = copy.deepcopy(os.environ)
         if own_xdg:
             shutil.rmtree(xdg_root, True)
@@ -455,6 +460,40 @@ class DBusUtil(Timeout):
                                 byte_arrays=True, 
                                 utf8_strings=True)
 
+    def setupFiles(self):
+        """ copy reference directory trees from test/test-dbus to own xdg(xdg_root
+        - destination directory) directory. Thus it won't do copy unless 
+        using own_xdg. Don't pollute user's directories """
+        if not self.own_xdg: 
+            return
+
+        # Get the absolute path of the current python file.
+        scriptpath = os.path.abspath(os.path.expanduser(os.path.expandvars(sys.argv[0])))
+
+        # reference directory 'test-dbus' is in the same directory as the current python file
+        sourcedir = os.path.join(os.path.dirname(scriptpath), 'test-dbus')
+
+        # if xdg_root doesn't exist, create it
+        if not os.access(xdg_root, os.F_OK):
+            os.makedirs(xdg_root)
+
+        """ Directories in test/test-dbus are copied to xdg_root, but
+        maybe with different names, mappings are:
+         test/test-dbus               ./test-dbus
+            sync4j                       .sync4j
+            data                         data
+            config                       config
+            cache                        cache   """
+        pairs = { 'sync4j' : '.sync4j', 'config' : 'config', 'cache' : 'cache', 'data' : 'data'}
+        for src, dest in pairs.items():
+            destpath = os.path.join(xdg_root, dest)
+            # make sure the dest directory does not exist, which is required by shutil.copytree
+            shutil.rmtree(destpath, True)
+            sourcepath = os.path.join(sourcedir, src)
+            # if source exists and could be accessed, then copy them
+            if os.access(sourcepath, os.F_OK):
+                shutil.copytree(sourcepath, destpath)
+
 class TestDBusServer(unittest.TestCase, DBusUtil):
     """Tests for the read-only Server API."""