Merge pull request #1 from effigies/enh/dicom_empty_string

TEST: Add de-identified, compressed DICOM with empty string in SliceThickness field

Author: mattcieslak

nibabel/nicom/tests/data/slicethickness_empty_string.dcm

@@ -35,6 +35,7 @@
 DATA_FILE_SLC_NORM = pjoin(IO_DATA_PATH, 'csa_slice_norm.dcm')
 DATA_FILE_DEC_RSCL = pjoin(IO_DATA_PATH, 'decimal_rescale.dcm')
 DATA_FILE_4D = pjoin(IO_DATA_PATH, '4d_multiframe_test.dcm')
+DATA_FILE_EMPTY_ST = pjoin(IO_DATA_PATH, 'slicethickness_empty_string.dcm')
 
 # This affine from our converted image was shown to match our image spatially
 # with an image from SPM DICOM conversion. We checked the matching with SPM
@@ -616,6 +617,11 @@ def test_data_real(self):
         assert_equal(sha1(dat_str).hexdigest(),
                      '149323269b0af92baa7508e19ca315240f77fa8c')
 
+    @dicom_test
+    def test_slicethickness_fallback(self):
+        dw = didw.wrapper_from_file(DATA_FILE_EMPTY_ST)
+        assert_equal(dw.voxel_sizes[2], 1.0)
+
     @dicom_test
     def test_data_fake(self):
         # Test algorithm for get_data