diff --git a/test/simulator/utils.py b/test/simulator/utils.py
index 3df996f..dce3f7c 100644
--- a/test/simulator/utils.py
+++ b/test/simulator/utils.py
@@ -31,9 +31,14 @@ def parse_varint(tx):
     # First of all, the offset of the hex transaction if moved to the proper position (i.e where the varint should be
     #  located) and the length and format of the data to be analyzed is checked.
     data = tx.hex[tx.offset :]
-    assert len(data) > 0
-    size = int(data[:2], 16)
-    assert size <= 255
+    if len(data) > 0:
+        size = int(data[:2], 16)
+
+    else:
+        raise ValueError("No data to be parsed")
+
+    if size > 255:
+        raise ValueError("Wrong value (varint size > 255)")
 
     # Then, the integer is encoded as a varint using the proper prefix, if needed.
     if size <= 252:  # No prefix
diff --git a/test/unit/test_block_processor.py b/test/unit/test_block_processor.py
index ab16736..69c03fe 100644
--- a/test/unit/test_block_processor.py
+++ b/test/unit/test_block_processor.py
@@ -2,6 +2,7 @@ import pytest
 
 from pisa import c_logger
 from pisa.block_processor import BlockProcessor
+from pisa.utils.auth_proxy import JSONRPCException
 from test.unit.conftest import get_random_value_hex
 
 c_logger.disabled = True
@@ -36,3 +37,33 @@ def test_get_random_block():
 def test_get_block_count():
     block_count = BlockProcessor.get_block_count()
     assert isinstance(block_count, int) and block_count >= 0
+
+
+def test_decode_raw_transaction():
+    # We cannot exhaustively test this (we rely on bitcoind for this) but we can try to decode a correct transaction
+    hex_tx = (
+        "0100000001c997a5e56e104102fa209c6a852dd90660a20b2d9c352423edce25857fcd3704000000004847304402"
+        "204e45e16932b8af514961a1d3a1a25fdf3f4f7732e9d624c6c61548ab5fb8cd410220181522ec8eca07de4860a4"
+        "acdd12909d831cc56cbbac4622082221a8768d1d0901ffffffff0200ca9a3b00000000434104ae1a62fe09c5f51b"
+        "13905f07f06b99a2f7159b2225f374cd378d71302fa28414e7aab37397f554a7df5f142c21c1b7303b8a0626f1ba"
+        "ded5c72a704f7e6cd84cac00286bee0000000043410411db93e1dcdb8a016b49840f8c53bc1eb68a382e97b1482e"
+        "cad7b148a6909a5cb2e0eaddfb84ccf9744464f82e160bfa9b8b64f9d4c03f999b8643f656b412a3ac00000000"
+    )
+
+    try:
+        BlockProcessor.decode_raw_transaction(hex_tx)
+        assert True
+    except JSONRPCException:
+        assert False
+
+
+def test_decode_raw_transaction_invalid():
+    # Same but with an invalid one
+
+    hex_tx = "A" * 16
+
+    try:
+        BlockProcessor.decode_raw_transaction(hex_tx)
+        assert False
+    except JSONRPCException:
+        assert True