RF: Skip test for python < 2.6 and pydicom < 1.0

Move pydicom import back to top level of module since we need its
version info for skipping the test, plus this removes duplicate
logic for importing 'pydicom' vs 'dicom'. Updated
test_csa_header_read to use the top level import as well.

Author: moloney

nibabel/nicom/tests/test_csareader.py

@@ -1,5 +1,6 @@
 """ Testing Siemens CSA header reader
 """
+import sys
 from os.path import join as pjoin
 from copy import deepcopy
 import gzip
@@ -11,9 +12,12 @@
 
 from nose.tools import (assert_true, assert_false, assert_equal, assert_raises)
 
+from numpy.testing.decorators import skipif
 
 from .test_dicomwrappers import (have_dicom, dicom_test,
                                  IO_DATA_PATH, DATA, DATA_FILE)
+if have_dicom:
+    from .test_dicomwrappers import pydicom
 
 CSA2_B0 = open(pjoin(IO_DATA_PATH, 'csa2_b0.bin'), 'rb').read()
 CSA2_B1000 = open(pjoin(IO_DATA_PATH, 'csa2_b1000.bin'), 'rb').read()
@@ -31,11 +35,7 @@ def test_csa_header_read():
     assert_true(csa.is_mosaic(hdr))
     # Get a shallow copy of the data, lacking the CSA marker
     # Need to do it this way because del appears broken in pydicom 0.9.7
-    try:
-        from dicom.dataset import Dataset
-    except ImportError:
-        from pydicom.dataset import Dataset
-    data2 = Dataset()
+    data2 = pydicom.dataset.Dataset()
     for element in DATA:
         if (element.tag.group, element.tag.elem) != (0x29, 0x10):
             data2.add(element)
@@ -132,16 +132,14 @@ def test_ice_dims():
 
 
 @dicom_test
+@skipif(sys.version_info < (2,7) and pydicom.__version__ < '1.0',
+        'Known issue for python 2.6 and pydicom < 1.0')
 def test_missing_csa_elem():
     # Test that we get None instead of raising an Exception when the file has
     # the PrivateCreator element for the CSA dict but not the element with the
     # actual CSA header (perhaps due to anonymization)
-    try:
-        from dicom.tag import Tag
-    except ImportError:
-        from pydicom.tag import Tag
     dcm = deepcopy(DATA)
-    csa_tag = Tag(0x29, 0x1010)
+    csa_tag = pydicom.dataset.Tag(0x29, 0x1010)
     del dcm[csa_tag]
     hdr = csa.get_csa_header(dcm, 'image')
     assert_equal(hdr, None)