add test

Signed-off-by: E3E <[email protected]>

securesystemslib/dsse.py

@@ -77,7 +77,7 @@ def to_dict(self) -> dict:
         """Returns the JSON-serializable dictionary representation of self."""
 
         signatures = []
-        for signature in list(self.signatures.values()):
+        for signature in self.signatures.values():
             sig_dict = signature.to_dict()
             sig_dict["sig"] = b64enc(bytes.fromhex(sig_dict["sig"]))
             signatures.append(sig_dict)
@@ -148,7 +148,7 @@ def verify(self, keys: List[Key], threshold: int) -> Dict[str, Key]:
         if len(keys) < threshold:
             raise ValueError("Number of keys can't be less than threshold")
 
-        for signature in list(self.signatures.values()):
+        for signature in self.signatures.values():
             for key in keys:
                 # If Signature keyid doesn't match with Key, skip.
                 if not key.keyid == signature.keyid:

tests/test_dsse.py

@@ -31,14 +31,28 @@ def setUpClass(cls):
         }
         cls.pae = b"DSSEv1 29 http://example.com/HelloWorld 11 hello world"
 
+    def test_envelope_from_dict_with_duplicate_signatures(self):
+        """Test envelope from_dict generates error with duplicate signature keyids"""
+        envelope_dict = copy.deepcopy(self.envelope_dict)
+
+        # add duplicate keyid.
+        envelope_dict["signatures"].append(copy.deepcopy(self.signature_dict))
+
+        # assert that calling from_dict will raise an error.
+        expected_error_message = f"Multiple signatures found for keyid {self.signature_dict['keyid']}"
+        with self.assertRaises(ValueError) as context:
+            Envelope.from_dict(envelope_dict)
+
+        self.assertEqual(str(context.exception), expected_error_message)
+
     def test_envelope_from_to_dict(self):
         """Test envelope to_dict and from_dict methods."""
 
         envelope_dict = copy.deepcopy(self.envelope_dict)
 
         # create envelope object from its dict.
         envelope_obj = Envelope.from_dict(envelope_dict)
-        for signature in list(envelope_obj.signatures.values()):
+        for signature in envelope_obj.signatures.values():
             self.assertIsInstance(signature, Signature)
 
         # Assert envelope dict created by to_dict will be equal.
@@ -105,7 +119,7 @@ def test_sign_and_verify(self):
 
         # Check for signatures of Envelope.
         self.assertEqual(len(self.key_dicts), len(envelope_obj.signatures))
-        for signature in list(envelope_obj.signatures.values()):
+        for signature in envelope_obj.signatures.values():
             self.assertIsInstance(signature, Signature)
 
         # Test for invalid threshold value for keys_list.