Create new expected_warnings helper and some cleanup

Add new helper function for expected warnings during test

Indentation cleanups and avoid skipping doctests if possible.

skimage/measure/_ccomp.pyx

@@ -416,12 +416,12 @@ def label(input, neighbors=None, background=None, return_num=False,
      [0 1 0]
      [0 0 1]]
     >>> from skimage.measure import label
-    >>> print(label(x, neighbors=4))  # doctest: +SKIP
+    >>> print(label(x, connectivity=1)) 
     [[0 1 1]
      [2 3 1]
      [2 2 4]]
 
-    >>> print(label(x, neighbors=8))  # doctest: +SKIP
+    >>> print(label(x, connectivity=2))
     [[0 1 1]
      [1 0 1]
      [1 1 0]]

skimage/measure/_regionprops.py

@@ -473,13 +473,13 @@ def regionprops(label_image, intensity_image=None, cache=True):
     >>> from skimage import data, util
     >>> from skimage.morphology import label
     >>> img = util.img_as_ubyte(data.coins()) > 110
-    >>> label_img = label(img)  # doctest: +SKIP
-    >>> props = regionprops(label_img)  # doctest: +SKIP
+    >>> label_img = label(img, connectivity=img.ndim)
+    >>> props = regionprops(label_img)
     >>> # centroid of first labeled object
-    >>> props[0].centroid   # doctest: +SKIP 
+    >>> props[0].centroid
     (22.729879860483141, 81.912285234465827)
     >>> # centroid of first labeled object
-    >>> props[0]['centroid']  # doctest: +SKIP 
+    >>> props[0]['centroid']
     (22.729879860483141, 81.912285234465827)
 
     """