Handle more warnings and reset io plugins as needed

Reset plugins prior to running collections test

Handle warnings in morphology pkg

Add __init__ for morpohology tests

Handle warnings for novice pkg

Handle warnings for restoration pkg

Handle warnings for segmentation pkg

Handle warnings for _shared pkg

Handle warnings for transform pkg

Handle warnings for util pkg

Handle warnings in viewer module

skimage/util/tests/__init__.py

@@ -0,0 +1,2 @@
+import warnings
+warnings.simplefilter('error')

skimage/util/tests/test_dtype.py

@@ -3,6 +3,7 @@ from numpy.testing import assert_equal, assert_raises
 from skimage import img_as_int, img_as_float, \
                     img_as_uint, img_as_ubyte
 from skimage.util.dtype import convert
+from skimage._shared.utils import all_warnings
 
 
 dtype_range = {np.uint8: (0, 255),
@@ -28,7 +29,9 @@ def test_range():
                         (img_as_float, np.float64),
                         (img_as_uint, np.uint16),
                         (img_as_ubyte, np.ubyte)]:
-            y = f(x)
+
+            with all_warnings():  # precision loss
+              y = f(x)
 
             omin, omax = dtype_range[dt]
 
@@ -59,7 +62,8 @@ def test_range_extra_dtypes():
     for dtype_in, dt in dtype_pairs:
         imin, imax = dtype_range_extra[dtype_in]
         x = np.linspace(imin, imax, 10).astype(dtype_in)
-        y = convert(x, dt)
+        with all_warnings():  # sign loss
+          y = convert(x, dt)
         omin, omax = dtype_range_extra[dt]
         yield (_verify_range,
                "From %s to %s" % (np.dtype(dtype_in), np.dtype(dt)),