Merge bitcoin#28669: test: check assumeutxo file for changed outpoint…

… index + de-duplications

d322368 test: De-dublicate/optimize assumeutxo test for further extensions (Fabian Jahr)
0a576d6 test: check au file with changed outpoint index (Fabian Jahr)

Pull request description:

  Also doing some de-duplications. I kept the second commit separate for now as I am not 100% if this is overdoing it and makes it harder to reason about. But it also makes it easier to add more cases where we change more data.

ACKs for top commit:
  maflcko:
    lgtm ACK d322368
  achow101:
    ACK d322368

Tree-SHA512: be950a34b0ed50cb58459df47cff6513df19d834bf81815572cd26b10dee26e6f80866f0c44023cf246aafbbd256e62d23ce903e8b07fdff2297bc7065799bb8

test/functional/feature_assumeutxo.py

@@ -69,15 +69,19 @@ def test_invalid_snapshot_scenarios(self, valid_snapshot_path):
             valid_snapshot_contents = f.read()
         bad_snapshot_path = valid_snapshot_path + '.mod'
 
+        def expected_error(log_msg="", rpc_details=""):
+            with self.nodes[1].assert_debug_log([log_msg]):
+                assert_raises_rpc_error(-32603, f"Unable to load UTXO snapshot{rpc_details}", self.nodes[1].loadtxoutset, bad_snapshot_path)
+
         self.log.info("  - snapshot file refering to a block that is not in the assumeutxo parameters")
         prev_block_hash = self.nodes[0].getblockhash(SNAPSHOT_BASE_HEIGHT - 1)
         bogus_block_hash = "0" * 64  # Represents any unknown block hash
         for bad_block_hash in [bogus_block_hash, prev_block_hash]:
             with open(bad_snapshot_path, 'wb') as f:
                 # block hash of the snapshot base is stored right at the start (first 32 bytes)
                 f.write(bytes.fromhex(bad_block_hash)[::-1] + valid_snapshot_contents[32:])
-            error_details = f"assumeutxo block hash in snapshot metadata not recognized ({bad_block_hash})"
-            assert_raises_rpc_error(-32603, f"Unable to load UTXO snapshot, {error_details}", self.nodes[1].loadtxoutset, bad_snapshot_path)
+            error_details = f", assumeutxo block hash in snapshot metadata not recognized ({bad_block_hash})"
+            expected_error(rpc_details=error_details)
 
         self.log.info("  - snapshot file with wrong number of coins")
         valid_num_coins = int.from_bytes(valid_snapshot_contents[32:32 + 8], "little")
@@ -86,18 +90,20 @@ def test_invalid_snapshot_scenarios(self, valid_snapshot_path):
                 f.write(valid_snapshot_contents[:32])
                 f.write((valid_num_coins + off).to_bytes(8, "little"))
                 f.write(valid_snapshot_contents[32 + 8:])
-            expected_log = f"bad snapshot - coins left over after deserializing 298 coins" if off == -1 else f"bad snapshot format or truncated snapshot after deserializing 299 coins"
-            with self.nodes[1].assert_debug_log([expected_log]):
-                assert_raises_rpc_error(-32603, "Unable to load UTXO snapshot", self.nodes[1].loadtxoutset, bad_snapshot_path)
-
-        self.log.info("  - snapshot file with wrong outpoint hash")
-        with open(bad_snapshot_path, "wb") as f:
-            f.write(valid_snapshot_contents[:(32 + 8)])
-            f.write(b"\xff" * 32)
-            f.write(valid_snapshot_contents[(32 + 8 + 32):])
-        expected_log = "[snapshot] bad snapshot content hash: expected ef45ccdca5898b6c2145e4581d2b88c56564dd389e4bd75a1aaf6961d3edd3c0, got 29926acf3ac81f908cf4f22515713ca541c08bb0f0ef1b2c3443a007134d69b8"
-        with self.nodes[1].assert_debug_log([expected_log]):
-            assert_raises_rpc_error(-32603, "Unable to load UTXO snapshot", self.nodes[1].loadtxoutset, bad_snapshot_path)
+            expected_error(log_msg=f"bad snapshot - coins left over after deserializing 298 coins" if off == -1 else f"bad snapshot format or truncated snapshot after deserializing 299 coins")
+
+        self.log.info("  - snapshot file with alternated UTXO data")
+        cases = [
+            [b"\xff" * 32, 0, "29926acf3ac81f908cf4f22515713ca541c08bb0f0ef1b2c3443a007134d69b8"], # wrong outpoint hash
+            [(1).to_bytes(4, "little"), 32, "798266c2e1f9a98fe5ce61f5951cbf47130743f3764cf3cbc254be129142cf9d"], # wrong outpoint index
+        ]
+
+        for content, offset, wrong_hash in cases:
+            with open(bad_snapshot_path, "wb") as f:
+                f.write(valid_snapshot_contents[:(32 + 8 + offset)])
+                f.write(content)
+                f.write(valid_snapshot_contents[(32 + 8 + offset + len(content)):])
+            expected_error(log_msg=f"[snapshot] bad snapshot content hash: expected ef45ccdca5898b6c2145e4581d2b88c56564dd389e4bd75a1aaf6961d3edd3c0, got {wrong_hash}")
 
     def run_test(self):
         """