TEST: Add DtypeOverrideMixin to test __init__ and to_filename dtype args

Author: effigies

nibabel/cifti2/tests/test_cifti2.py

@@ -12,7 +12,7 @@
 import pytest
 
 from nibabel.tests.test_dataobj_images import TestDataobjAPI as _TDA
-from nibabel.tests.test_image_api import SerializeMixin
+from nibabel.tests.test_image_api import SerializeMixin, DtypeOverrideMixin
 
 
 def compare_xml_leaf(str1, str2):
@@ -415,7 +415,7 @@ def test_underscoring():
         assert ci.cifti2._underscore(camel) == underscored
 
 
-class TestCifti2ImageAPI(_TDA, SerializeMixin):
+class TestCifti2ImageAPI(_TDA, SerializeMixin, DtypeOverrideMixin):
     """ Basic validation for Cifti2Image instances
     """
     # A callable returning an image from ``image_maker(data, header)``
@@ -426,6 +426,8 @@ class TestCifti2ImageAPI(_TDA, SerializeMixin):
     ni_header_maker = Nifti2Header
     example_shapes = ((2,), (2, 3), (2, 3, 4))
     standard_extension = '.nii'
+    storable_dtypes = (np.int8, np.uint8, np.int16, np.uint16, np.int32, np.uint32,
+                       np.int64, np.uint64, np.float32, np.float64)
 
     def make_imaker(self, arr, header=None, ni_header=None):
         for idx, sz in enumerate(arr.shape):

nibabel/tests/test_image_api.py

@@ -55,6 +55,8 @@
 from .test_parrec import EXAMPLE_IMAGES as PARREC_EXAMPLE_IMAGES
 from .test_brikhead import EXAMPLE_IMAGES as AFNI_EXAMPLE_IMAGES
 
+from nibabel.arraywriters import WriterError
+
 
 def maybe_deprecated(meth_name):
     return pytest.deprecated_call() if meth_name == 'get_data' else nullcontext()
@@ -181,7 +183,7 @@ def validate_get_data_deprecated(self, imaker, params):
         assert_array_equal(np.asanyarray(img.dataobj), data)
 
 
-class GetSetDtypeMixin(object):
+class GetSetDtypeMixin:
     """ Adds dtype tests
 
     Add this one if your image has ``get_data_dtype`` and ``set_data_dtype``.
@@ -666,6 +668,46 @@ def prox_imaker():
             yield make_prox_imaker(arr.copy(), aff, hdr), params
 
 
+class DtypeOverrideMixin(GetSetDtypeMixin):
+    """ Test images that can accept ``dtype`` arguments to ``__init__`` and
+    ``to_file_map``
+    """
+
+    def validate_init_dtype_override(self, imaker, params):
+        img = imaker()
+        klass = img.__class__
+        for dtype in self.storable_dtypes:
+            if hasattr(img, 'affine'):
+                new_img = klass(img.dataobj, img.affine, header=img.header, dtype=dtype)
+            else:  # XXX This is for CIFTI-2, these validators might need refactoring
+                new_img = klass(img.dataobj, header=img.header, dtype=dtype)
+            assert new_img.get_data_dtype() == dtype
+
+            if self.has_scaling and self.can_save:
+                with np.errstate(invalid='ignore'):
+                    rt_img = bytesio_round_trip(new_img)
+                assert rt_img.get_data_dtype() == dtype
+
+    def validate_to_file_dtype_override(self, imaker, params):
+        if not self.can_save:
+            raise unittest.SkipTest
+        img = imaker()
+        orig_dtype = img.get_data_dtype()
+        fname = 'image' + self.standard_extension
+        with InTemporaryDirectory():
+            for dtype in self.storable_dtypes:
+                try:
+                    img.to_filename(fname, dtype=dtype)
+                except WriterError:
+                    # It's possible to try to save to a dtype that requires
+                    # scaling, and images without scale factors will fail.
+                    # We're not testing that here.
+                    continue
+                rt_img = img.__class__.from_filename(fname)
+                assert rt_img.get_data_dtype() == dtype
+                assert img.get_data_dtype() == orig_dtype
+
+
 class ImageHeaderAPI(MakeImageAPI):
     """ When ``self.image_maker`` is an image class, make header from class
     """
@@ -674,7 +716,12 @@ def header_maker(self):
         return self.image_maker.header_class()
 
 
-class TestAnalyzeAPI(ImageHeaderAPI):
+class TestSpatialImageAPI(ImageHeaderAPI):
+    klass = image_maker = SpatialImage
+    can_save = False
+
+
+class TestAnalyzeAPI(TestSpatialImageAPI, DtypeOverrideMixin):
     """ General image validation API instantiated for Analyze images
     """
     klass = image_maker = AnalyzeImage
@@ -685,11 +732,6 @@ class TestAnalyzeAPI(ImageHeaderAPI):
     storable_dtypes = (np.uint8, np.int16, np.int32, np.float32, np.float64)
 
 
-class TestSpatialImageAPI(TestAnalyzeAPI):
-    klass = image_maker = SpatialImage
-    can_save = False
-
-
 class TestSpm99AnalyzeAPI(TestAnalyzeAPI):
     # SPM-type analyze need scipy for mat file IO
     klass = image_maker = Spm99AnalyzeImage