Improve test coverage

Author: bjmc

jose/jwt.py

@@ -425,7 +425,7 @@ def _validate_at_hash(claims, access_token, algorithm):
     try:
         expected_hash = calculate_at_hash(access_token,
                                           ALGORITHMS.HASHES[algorithm])
-    except TypeError:
+    except (TypeError, ValueError):
         msg = 'Unable to calculate at_hash to verify against token claims.'
         raise JWTClaimsError(msg)
 

tests/test_jwt.py

@@ -449,6 +449,11 @@ def test_at_hash_missing_claim(self, claims, key):
         with pytest.raises(JWTError):
             jwt.decode(token, key, access_token='<ACCESS_TOKEN>')
 
+    def test_at_hash_unable_to_calculate(self, claims, key):
+        token = jwt.encode(claims, key, access_token='<ACCESS_TOKEN>')
+        with pytest.raises(JWTError):
+            jwt.decode(token, key, access_token='\xe2')
+
     def test_unverified_claims_string(self):
         token = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.aW52YWxpZCBjbGFpbQ.iOJ5SiNfaNO_pa2J4Umtb3b3zmk5C18-mhTCVNsjnck'
         with pytest.raises(JWTError):