mark a test function as no cover, and add a test to cover an error case

casimport/__init__.py

@@ -38,7 +38,7 @@ import urllib.request
 from importlib.abc import MetaPathFinder, Loader
 from importlib.machinery import ModuleSpec
 
-def _printanyexc(f):
+def _printanyexc(f):	# pragma: no cover
 	'''Prints any exception that gets raised by the wrapped function.'''
 
 	@functools.wraps(f)
@@ -582,8 +582,16 @@ class Test(unittest.TestCase):
 		self.assertEqual(data, ipfsdata)
 
 		with self.assertRaises(ValueError):
+			# that a hash url fails
 			ipfs.fetch_data(urllib.parse.urlparse('hash://sha256/asldfkj'))
 
+		# that when the request fails
+		uomock.return_value.__enter__.return_value.status = 400
+
+		# it raises a RuntimeError
+		with self.assertRaises(RuntimeError):
+			ipfs.fetch_data(hashurl)
+
 	def test_overlappingaliases(self):
 		# make sure that an aliases file is consistent and does not
 		# override other urls.  That is that any hashes are