add a few case to get 100% coverage

shamirss.py

@@ -22,6 +22,10 @@
 # SUCH DAMAGE.
 #
 
+#
+# ls shamirss.py | entr sh -c ' date; python -m coverage run -m unittest shamirss && coverage report -m'
+#
+
 import functools
 import operator
 import secrets
@@ -220,7 +224,7 @@ class TestShamirSS(unittest.TestCase):
 
 			invcache = (None, ) + tuple(int(GF2p8(x) ** -1) for x in range(1, 256))
 
-		if GF2p8._invcache != invcache:
+		if GF2p8._invcache != invcache: # pragma: no cover
 			print('inv cache:', repr(invcache))
 			self.assertEqual(GF2p8._invcache, invcache)
 
@@ -240,7 +244,13 @@ class TestShamirSS(unittest.TestCase):
 			for j in range(10):
 				self.assertEqual(powers[j], a ** j)
 
+	def test_gf2p8_errors(self):
+		self.assertRaises(ValueError, GF2p8, 1000)
+
 	def test_gf2p8(self):
+		self.assertEqual(int(GF2p8(5)), 5)
+		self.assertEqual(repr(GF2p8(5)), 'GF2p8(5)')
+
 		for i in range(10):
 			a = GF2p8(random.randint(0, 255))
 			b = GF2p8(random.randint(0, 255))