Index: spongenet/trunk/mini_andi_expand_config.py
===================================================================
--- spongenet/trunk/mini_andi_expand_config.py (revision 344)
+++ spongenet/trunk/mini_andi_expand_config.py (revision 373)
@@ -5,11 +5,11 @@
 import os
 
-zipdir = "/seacoos/data/nccoos/level0/largo/mini_andi/zip"
-xmldir = "/seacoos/data/nccoos/level0/largo/mini_andi/xml"
-zipdir_pattern = "[0-9][0-9][0-9][0-9]_[0-9][0-9]"
-zipfile_pattern = "[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]T" \
+ZIPDIR = "/seacoos/data/nccoos/level0/largo/mini_andi/zip"
+XMLDIR = "/seacoos/data/nccoos/level0/largo/mini_andi/xml"
+ZIPDIR_PATTERN = "[0-9][0-9][0-9][0-9]_[0-9][0-9]"
+ZIPFILE_PATTERN = "[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]T" \
                   "[0-9][0-9][0-9][0-9][0-9][0-9]-" \
                   "[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]T" \
                   "[0-9][0-9][0-9][0-9][0-9][0-9].zip"
-xmlfile_pattern = "[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]T" \
+XMLFILE_PATTERN = "[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]T" \
                   "[0-9][0-9][0-9][0-9][0-9][0-9].xml"
Index: spongenet/trunk/spongenet/expand.py
===================================================================
--- spongenet/trunk/spongenet/expand.py (revision 351)
+++ spongenet/trunk/spongenet/expand.py (revision 373)
@@ -290,6 +290,6 @@
 
     # Write a combined XML sponge data file.
-    path = xml_subdir + os.extsep + "xml"
-    with open(path, "w") as handle:
+    xml_path = xml_subdir + os.extsep + "xml"
+    with open(xml_path, "w") as handle:
         handle.write(header)
         handle.write("<root>\n")
@@ -372,15 +372,27 @@
             xml_subdir = os.path.splitext(os.path.basename(zip_file))[0]
             xml_subdir = os.path.join(xml_month, xml_subdir)
-            if not os.path.exists(xml_subdir):
-                os.mkdir(xml_subdir, 0755)
-                # Extract all the XML files in the zip file
-                # and combine into a single XML document.
-                archive = zipfile.ZipFile(zip_file, "r")
-                archive.extractall(xml_subdir)
-                combine(xml_subdir, xmlfile_pattern)
-            elif not os.path.isdir(xml_subdir):
-                raise IOError("XML file subdirectory name " + \
+            xml_path = xml_subdir + os.extsep + "xml"
+            if not os.path.exists(xml_path):
+                if not os.path.exists(xml_subdir):
+                    os.mkdir(xml_subdir, 0755)
+                    # Extract all the XML files in the zip file
+                    # and combine into a single XML document.
+                    archive = zipfile.ZipFile(zip_file, "r")
+                    archive.extractall(xml_subdir)
+                    combine(xml_subdir, xmlfile_pattern)
+                elif not os.path.isdir(xml_subdir):
+                    raise IOError("XML file subdirectory name " + \
+                                  xml_subdir + \
+                                  " exists and is not a directory.")
+            elif not os.path.isfile(xml_path):
+                raise IOError("XML file name " + \
+                              xml_path + \
+                              " exists and is not a file.")
+            elif os.path.exists(xml_subdir):
+                raise IOError("XML file name " + \
+                              xml_path + \
+                              "and XML file subdirectory name " + \
                               xml_subdir + \
-                              " exists and is not a directory.")
+                              " both exist.")
 
     return
@@ -391,7 +403,18 @@
     Run module as script.
 
-    Test silent import.
-
-    >>> from expand import _main
+    Supply incomplete config file.
+
+    >>> save_stdout = sys.stdout
+    >>> temp_stdout = StringIO()
+    >>> sys.stdout = temp_stdout
+    >>> _config_path = os.path.join(
+    ...                    os.path.dirname(
+    ...                        os.path.abspath(__file__)),
+    ...                    TEST_PATH, "incomplete_config.py")
+    >>> sys.argv = ["", _config_path]
+    >>> _main()
+    >>> sys.stdout = save_stdout
+    >>> USAGE == temp_stdout.getvalue()[:-1]
+    True
     """
 
@@ -401,4 +424,6 @@
         if all(_config):
             expand(*_config)
+        else:
+            print USAGE
     return
 
Index: spongenet/trunk/spongenet/tests/expand/incomplete_config.py
===================================================================
---  (revision )
+++ spongenet/trunk/spongenet/tests/expand/incomplete_config.py (revision 373)
@@ -1,0 +1,19 @@
+#!/usr/bin/env python
+
+"""Incomplete test configuration for the expand module."""
+
+import os
+
+EXPAND_TEST_PATH = os.path.join("tests", "expand")
+
+zipdir = os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                      EXPAND_TEST_PATH, "zip")
+xmldir = os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                      EXPAND_TEST_PATH, "xml")
+zipdir_pattern = "[0-9][0-9][0-9][0-9]_[0-9][0-9]"
+zipfile_pattern = "[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]T" \
+                  "[0-9][0-9][0-9][0-9][0-9][0-9]-" \
+                  "[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]T" \
+                  "[0-9][0-9][0-9][0-9][0-9][0-9].zip"
+xmlfile_pattern = "[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]T" \
+                  "[0-9][0-9][0-9][0-9][0-9][0-9].xml"