RF+TST: test PARREC array proxy API; add slicing

Add `__getitem__` placeholder method for PARRECArrayProxy, to fulfill
required API, and test with API validators.

Author: matthew-brett

nibabel/parrec.py

@@ -561,6 +561,9 @@ def __array__(self):
                                   scalings=self._slice_scaling,
                                   mmap=self._mmap)
 
+    def __getitem__(self, slicer):
+        return np.asanyarray(self)[slicer]
+
 
 class PARRECHeader(Header):
     """PAR/REC header"""

nibabel/tests/test_proxy_api.py

@@ -48,6 +48,7 @@
 from ..optpkg import optional_package
 h5py, have_h5py, _ = optional_package('h5py')
 from .. import ecat
+from .. import parrec
 
 from ..arrayproxy import ArrayProxy, is_proxy
 
@@ -63,6 +64,8 @@
 
 from .test_api_validators import ValidateAPI
 
+from .test_parrec import EG_PAR, EG_REC
+
 def _some_slicers(shape):
     ndim = len(shape)
     slicers = np.eye(ndim).astype(np.int).astype(object)
@@ -368,3 +371,19 @@ def eg_func():
 
     def validate_header_isolated(self, pmaker, params):
         raise SkipTest('ECAT header does not support dtype get')
+
+
+class TestPARRECAPI(_TestProxyAPI):
+
+    def obj_params(self):
+        img = parrec.load(EG_PAR)
+        arr_out = img.get_data()
+        def eg_func():
+            img = parrec.load(EG_PAR)
+            prox = parrec.PARRECArrayProxy(EG_REC, img.header, 'dv')
+            fobj = open(EG_REC, 'rb')
+            return prox, fobj, img.header
+        yield (eg_func,
+               dict(shape = (64, 64, 9, 3),
+                    dtype_out=np.float64,
+                    arr_out=arr_out))