always reads raw_timestamps on defragment, add test for data round trip

nptdms/test/test_example_files.py

@@ -38,7 +38,17 @@ def test_defragment_raw_timestamps():
     """Test defragmenting a file with raw timestamps"""
     test_file_path = DATA_DIR + '/raw_timestamps.tdms'
     output_file = BytesIO()
-    TdmsWriter.defragment(test_file_path, output_file, raw_timestamps=True)
+
+    # verify we can defragment a file with raw timestamps
+    TdmsWriter.defragment(test_file_path, output_file)
+
+    # verify that both files' channel data are the same
+    input_tdms = tdms.TdmsFile(test_file_path)
+    output_file.seek(0)
+    output_tdms = tdms.TdmsFile(output_file)
+    for group in input_tdms.groups():
+        for channel in group.channels():
+            np.testing.assert_equal(channel.data, output_tdms[group.name][channel.name].data)
 
 
 def test_big_endian_format():

nptdms/writer.py

@@ -22,7 +22,7 @@ class TdmsWriter(object):
     """
 
     @classmethod
-    def defragment(cls, source, destination, version=4712, index_file=False, raw_timestamps=False):
+    def defragment(cls, source, destination, version=4712, index_file=False):
         """ Defragemnts an existing TdmsFile by loading and moving each Object to a separate channel
         to stream read one consecutive part of the file for faster access.
 
@@ -39,7 +39,7 @@ def defragment(cls, source, destination, version=4712, index_file=False, raw_tim
             If ``destination`` is a readable object ``index_file`` can either be a redable object or ``False``
             to store a ``.tdms_index`` file inside of the submitted object or not.
         """
-        file = TdmsFile(source, raw_timestamps)
+        file = TdmsFile(source, raw_timestamps=True)
         with cls(destination, version=version, index_file=index_file) as new_file:
             new_file.write_segment([RootObject(file.properties)])
             for group in file.groups():