test: improve coverage with Copilot suggestions

Signed-off-by: adityashirsatrao007 <adityashirsatrao007@gmail.com>

Author: adityashirsatrao007

tests/unit/crypto_utils_test.py

@@ -20,6 +20,9 @@ def test_keccak256():
     # "hello" -> 1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8
     assert keccak256(b"hello").hex() == "1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8"
 
+    # "Transfer" -> 461a29a8a7db848c0827103038dd4776114eb182e0717208d0a793574936353d
+    assert keccak256(b"Transfer").hex() == "f099cd8bde557814842a3121e8ddfd433a539b8c9f14bf31ebf108d12e6196e9"
+
 
 def test_compress_point_unchecked():
     """Test point compression logic."""
@@ -59,6 +62,16 @@ def test_decompress_point():
     assert x2 == nums.x
     assert y2 == nums.y
 
+    # Test invalid length
+    with pytest.raises(ValueError, match="Not recognized"):
+        decompress_point(b'\x04' * 10)
+
+    # Test invalid prefix
+    with pytest.raises(ValueError, match="Not recognized"):
+        # 0x05 is invalid prefix for 33-byte point
+        invalid_point = b'\x05' + nums.x.to_bytes(32, 'big')
+        decompress_point(invalid_point)
+
 
 def test_compress_with_cryptography():
     """Test compression using cryptography library."""