TEST: path_maybe_image part of image API

Not all tests have image_maker attributes, so add klass attribute to
test path_maybe_image. Checks structure of return values on calls to
example images.

Author: effigies

nibabel/tests/test_image_api.py

@@ -24,6 +24,7 @@
 
 import warnings
 from functools import partial
+from ..externals.six import string_types
 
 import numpy as np
 
@@ -283,11 +284,21 @@ class LoadImageAPI(GenericImageAPI):
     # Sequence of dictionaries, where dictionaries have keys
     # 'fname" in addition to keys for ``params`` (see obj_params docstring)
     example_images = ()
+    # Class of images to be tested
+    klass = None
 
     def obj_params(self):
         for img_params in self.example_images:
             yield lambda : self.loader(img_params['fname']), img_params
 
+    def validate_path_maybe_image(self, imaker, params):
+        for img_params in self.example_images:
+            test, sniff = self.klass.path_maybe_image(img_params['fname'])
+            assert_true(isinstance(test, bool))
+            if sniff is not None:
+                assert isinstance(sniff[0], bytes)
+                assert isinstance(sniff[1], string_types)
+
 
 class MakeImageAPI(LoadImageAPI):
     """ Validation for images we can make with ``func(data, affine, header)``
@@ -346,48 +357,48 @@ def header_maker(self):
 class TestAnalyzeAPI(ImageHeaderAPI):
     """ General image validation API instantiated for Analyze images
     """
-    image_maker = AnalyzeImage
+    klass = image_maker = AnalyzeImage
     has_scaling = False
     can_save = True
     standard_extension = '.img'
 
 
 class TestSpatialImageAPI(TestAnalyzeAPI):
-    image_maker = SpatialImage
+    klass = image_maker = SpatialImage
     can_save = False
 
 
 class TestSpm99AnalyzeAPI(TestAnalyzeAPI):
     # SPM-type analyze need scipy for mat file IO
-    image_maker = Spm99AnalyzeImage
+    klass = image_maker = Spm99AnalyzeImage
     has_scaling = True
     can_save = have_scipy
 
 
 class TestSpm2AnalyzeAPI(TestSpm99AnalyzeAPI):
-    image_maker = Spm2AnalyzeImage
+    klass = image_maker = Spm2AnalyzeImage
 
 
 class TestNifti1PairAPI(TestSpm99AnalyzeAPI):
-    image_maker = Nifti1Pair
+    klass = image_maker = Nifti1Pair
     can_save = True
 
 
 class TestNifti1API(TestNifti1PairAPI):
-    image_maker = Nifti1Image
+    klass = image_maker = Nifti1Image
     standard_extension = '.nii'
 
 
 class TestNifti2PairAPI(TestNifti1PairAPI):
-    image_maker = Nifti2Pair
+    klass = image_maker = Nifti2Pair
 
 
 class TestNifti2API(TestNifti1API):
-    image_maker = Nifti2Image
+    klass = image_maker = Nifti2Image
 
 
 class TestMinc1API(ImageHeaderAPI):
-    image_maker = Minc1Image
+    klass = image_maker = Minc1Image
     loader = minc1.load
     example_images = MINC1_EXAMPLE_IMAGES
 
@@ -397,7 +408,7 @@ def __init__(self):
         if not have_h5py:
             raise SkipTest('Need h5py for these tests')
 
-    image_maker = Minc2Image
+    klass = image_maker = Minc2Image
     loader = minc2.load
     example_images = MINC2_EXAMPLE_IMAGES
 
@@ -406,6 +417,7 @@ class TestPARRECAPI(LoadImageAPI):
     def loader(self, fname):
         return parrec.load(fname)
 
+    klass = parrec.PARRECImage
     example_images = PARREC_EXAMPLE_IMAGES
 
 
@@ -418,7 +430,7 @@ def loader(self, fname):
 
 
 class TestMGHAPI(ImageHeaderAPI):
-    image_maker = MGHImage
+    klass = image_maker = MGHImage
     example_shapes = ((2, 3, 4), (2, 3, 4, 5)) # MGH can only do >= 3D
     has_scaling = True
     can_save = True