RF: split up image API tester into mixins

Make a generic file-based image API tester, and split dataobj, affine,
dtype, and header shape tests into their own mixins.  Mix these in to
restore the original set of tests.

The refactoring is to allow tests of FileBasedImage and DataobjImage.

Author: matthew-brett

nibabel/tests/test_image_api.py

@@ -47,7 +47,8 @@
 from ..tmpdirs import InTemporaryDirectory
 
 from .test_api_validators import ValidateAPI
-from .test_helpers import bytesio_round_trip, assert_data_similar
+from .test_helpers import (bytesio_round_trip, bytesio_filemap,
+                           assert_data_similar)
 from .test_minc1 import EXAMPLE_IMAGES as MINC1_EXAMPLE_IMAGES
 from .test_minc2 import EXAMPLE_IMAGES as MINC2_EXAMPLE_IMAGES
 from .test_parrec import EXAMPLE_IMAGES as PARREC_EXAMPLE_IMAGES
@@ -100,38 +101,10 @@ def obj_params(self):
         """
         raise NotImplementedError
 
-    def validate_affine(self, imaker, params):
-        # Check affine API
-        img = imaker()
-        assert_almost_equal(img.affine, params['affine'], 6)
-        assert_equal(img.affine.dtype, np.float64)
-        img.affine[0, 0] = 1.5
-        assert_equal(img.affine[0, 0], 1.5)
-        # Read only
-        assert_raises(AttributeError, setattr, img, 'affine', np.eye(4))
-
-    def validate_affine_deprecated(self, imaker, params):
-        # Check deprecated affine API
-        img = imaker()
-        with clear_and_catch_warnings() as w:
-            warnings.simplefilter('always', DeprecationWarning)
-            assert_almost_equal(img.get_affine(), params['affine'], 6)
-            assert_equal(len(w), 1)
-            assert_equal(img.get_affine().dtype, np.float64)
-            aff = img.get_affine()
-            aff[0, 0] = 1.5
-            assert_true(aff is img.get_affine())
-
     def validate_header(self, imaker, params):
         # Check header API
         img = imaker()
         hdr = img.header  # we can fetch it
-        # Change shape in header, check this changes img.header
-        shape = hdr.get_data_shape()
-        new_shape = (shape[0] + 1,) + shape[1:]
-        hdr.set_data_shape(new_shape)
-        assert_true(img.header is hdr)
-        assert_equal(img.header.get_data_shape(), new_shape)
         # Read only
         assert_raises(AttributeError, setattr, img, 'header', hdr)
 
@@ -152,7 +125,6 @@ def validate_shape(self, imaker, params):
         # Same as array shape if passed
         if 'data' in params:
             assert_equal(img.shape, params['data'].shape)
-        assert_equal(img.shape, img.get_data().shape)
         # Read only
         assert_raises(AttributeError, setattr, img, 'shape', np.eye(4))
 
@@ -164,6 +136,51 @@ def validate_shape_deprecated(self, imaker, params):
             assert_equal(img.get_shape(), params['shape'])
             assert_equal(len(w), 1)
 
+    def validate_filenames(self, imaker, params):
+        # Validate the filename, file_map interface
+        if not self.can_save:
+            raise SkipTest
+        img = imaker()
+        img.set_data_dtype(np.float32)  # to avoid rounding in load / save
+        # Make sure the object does not have a file_map
+        img.file_map = None
+        # The bytesio_round_trip helper tests bytesio load / save via file_map
+        rt_img = bytesio_round_trip(img)
+        assert_array_equal(img.shape, rt_img.shape)
+        assert_almost_equal(img.get_data(), rt_img.get_data())
+        # Give the image a file map
+        klass = type(img)
+        rt_img.file_map = bytesio_filemap(klass)
+        # This object can now be saved and loaded from its own file_map
+        rt_img.to_file_map()
+        rt_rt_img = klass.from_file_map(rt_img.file_map)
+        assert_almost_equal(img.get_data(), rt_rt_img.get_data())
+        # get_ / set_ filename
+        fname = 'an_image' + self.standard_extension
+        img.set_filename(fname)
+        assert_equal(img.get_filename(), fname)
+        assert_equal(img.file_map['image'].filename, fname)
+        # to_ / from_ filename
+        fname = 'another_image' + self.standard_extension
+        with InTemporaryDirectory():
+            img.to_filename(fname)
+            rt_img = img.__class__.from_filename(fname)
+            assert_array_equal(img.shape, rt_img.shape)
+            assert_almost_equal(img.get_data(), rt_img.get_data())
+            del rt_img  # to allow windows to delete the directory
+
+    def validate_no_slicing(self, imaker, params):
+        img = imaker()
+        assert_raises(TypeError, img.__getitem__, 'string')
+        assert_raises(TypeError, img.__getitem__, slice(None))
+
+
+class GetSetDtypeMixin(object):
+    """ Adds dtype tests
+
+    Add this one if your image has ``get_data_dtype`` and ``set_data_dtype``.
+    """
+
     def validate_dtype(self, imaker, params):
         # data / storage dtype
         img = imaker()
@@ -182,9 +199,17 @@ def validate_dtype(self, imaker, params):
             rt_img = bytesio_round_trip(img)
             assert_equal(rt_img.get_data_dtype().type, np.float32)
 
-    def validate_data(self, imaker, params):
+
+class DataInterfaceMixin(GetSetDtypeMixin):
+    """ Test dataobj interface for images with array backing
+
+    Use this mixin if your image has a ``dataobj`` property that contains an
+    array or an array-like thing.
+    """
+    def validate_data_interface(self, imaker, params):
         # Check get data returns array, and caches
         img = imaker()
+        assert_equal(img.shape, img.dataobj.shape)
         assert_data_similar(img.dataobj, params)
         if params['is_proxy']:
             assert_false(isinstance(img.dataobj, np.ndarray))
@@ -243,6 +268,8 @@ def validate_data(self, imaker, params):
                 img.uncache()
                 assert_array_equal(get_data_func(), 42)
                 assert_true(img.in_memory)
+        # Data shape is same as image shape
+        assert_equal(img.shape, img.get_data().shape)
         # dataobj is read only
         fake_data = np.zeros(img.shape).astype(img.get_data_dtype())
         assert_raises(AttributeError, setattr, img, 'dataobj', fake_data)
@@ -262,37 +289,60 @@ def validate_data_deprecated(self, imaker, params):
         fake_data = np.zeros(img.shape).astype(img.get_data_dtype())
         assert_raises(AttributeError, setattr, img, '_data', fake_data)
 
-    def validate_filenames(self, imaker, params):
-        # Validate the filename, file_map interface
-        if not self.can_save:
-            raise SkipTest
+
+class HeaderShapeMixin(object):
+    """ Tests that header shape can be set and got
+
+    Add this one of your header supports ``get_data_shape`` and
+    ``set_data_shape``.
+    """
+
+    def validate_header_shape(self, imaker, params):
+        # Change shape in header, check this changes img.header
         img = imaker()
-        img.set_data_dtype(np.float32)  # to avoid rounding in load / save
-        # The bytesio_round_trip helper tests bytesio load / save via file_map
-        rt_img = bytesio_round_trip(img)
-        assert_array_equal(img.shape, rt_img.shape)
-        assert_almost_equal(img.get_data(), rt_img.get_data())
-        # get_ / set_ filename
-        fname = 'an_image' + self.standard_extension
-        img.set_filename(fname)
-        assert_equal(img.get_filename(), fname)
-        assert_equal(img.file_map['image'].filename, fname)
-        # to_ / from_ filename
-        fname = 'another_image' + self.standard_extension
-        with InTemporaryDirectory():
-            img.to_filename(fname)
-            rt_img = img.__class__.from_filename(fname)
-            assert_array_equal(img.shape, rt_img.shape)
-            assert_almost_equal(img.get_data(), rt_img.get_data())
-            del rt_img  # to allow windows to delete the directory
+        hdr = img.header
+        shape = hdr.get_data_shape()
+        new_shape = (shape[0] + 1,) + shape[1:]
+        hdr.set_data_shape(new_shape)
+        assert_true(img.header is hdr)
+        assert_equal(img.header.get_data_shape(), new_shape)
 
-    def validate_no_slicing(self, imaker, params):
+
+class AffineMixin(object):
+    """ Adds test of affine property, method
+
+    Add this one if your image has an ``affine`` property.  If so, it should
+    (for now) also have a ``get_affine`` method returning the same result.
+    """
+
+    def validate_affine(self, imaker, params):
+        # Check affine API
         img = imaker()
-        assert_raises(TypeError, img.__getitem__, 'string')
-        assert_raises(TypeError, img.__getitem__, slice(None))
+        assert_almost_equal(img.affine, params['affine'], 6)
+        assert_equal(img.affine.dtype, np.float64)
+        img.affine[0, 0] = 1.5
+        assert_equal(img.affine[0, 0], 1.5)
+        # Read only
+        assert_raises(AttributeError, setattr, img, 'affine', np.eye(4))
+
+    def validate_affine_deprecated(self, imaker, params):
+        # Check deprecated affine API
+        img = imaker()
+        with clear_and_catch_warnings() as w:
+            warnings.simplefilter('always', DeprecationWarning)
+            assert_almost_equal(img.get_affine(), params['affine'], 6)
+            assert_equal(len(w), 1)
+            assert_equal(img.get_affine().dtype, np.float64)
+            aff = img.get_affine()
+            aff[0, 0] = 1.5
+            assert_true(aff is img.get_affine())
 
 
-class LoadImageAPI(GenericImageAPI):
+class LoadImageAPI(GenericImageAPI,
+                   DataInterfaceMixin,
+                   AffineMixin,
+                   GetSetDtypeMixin,
+                   HeaderShapeMixin):
     # Callable returning an image from a filename
     loader = None
     # Sequence of dictionaries, where dictionaries have keys
@@ -324,9 +374,6 @@ class MakeImageAPI(LoadImageAPI):
     # Example shapes for created images
     example_shapes = ((2,), (2, 3), (2, 3, 4), (2, 3, 4, 5))
 
-    def img_from_arr_aff(self, arr, aff, header=None):
-        return self.image_maker(arr, aff, header)
-
     def obj_params(self):
         # Return any obj_params from superclass
         for func, params in super(MakeImageAPI, self).obj_params():