Refactoring and improve coverage

Author: Andrew Yang

Diff for: src/diffpy/utils/parsers/__init__.py

@@ -17,10 +17,11 @@
 """
 
 from .loaddata import loadData
-from .loadmetafile import serialize_data, deserialize_data, apply_schema_to_file, serial_oneline
+from .serialization import serialize_data, deserialize_data
 from .resample import resample
 
 # silence the pyflakes syntax checker
 assert loadData or resample or True
+assert serialize_data or deserialize_data or True
 
 # End of file

Diff for: src/diffpy/utils/parsers/custom_exceptions.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python
+##############################################################################
+#
+# diffpy.utils      by DANSE Diffraction group
+#                   Simon J. L. Billinge
+#                   (c) 2010 The Trustees of Columbia University
+#                   in the City of New York.  All rights reserved.
+#
+# File coded by:
+#
+# See AUTHORS.txt for a list of people who contributed.
+# See LICENSE_DANSE.txt for license information.
+#
+##############################################################################
+
+class UnsupportedTypeError(Exception):
+    """For file types not supported by our parsers.
+
+    supported_types     -- List of supported types.
+    file                -- file triggering the error.
+    message             -- for writing a custom message.
+    """
+
+    def __init__(self, file, supported_types=None, message=None):
+        if message is None:
+            self.message = f"The file {file} is not supported."
+            if supported_types is not None:
+                self.message += " Supported file types include: "
+            for t in supported_types:
+                self.message += t + ", "
+            self.message = self.message[:-2] + "."
+        super().__init__(self.message)
+
+
+class ImproperSizeError(Exception):
+    """When the size of an object does not match expectations.
+
+    bad_object          -- Object with improper size.
+    message             -- for writing a custom message.
+    """
+
+    def __init__(self, bad_object, message=None):
+        if message is None:
+            self.message = f"The size of {bad_object} is different than expected."
+        super().__init__(self.message)