test: dedup file hashing using sha256sum_file helper

Rather than doing the open/read/hash-steps manually in the affected
functional tests, we can just use the `sha256sum_file` helper from the
utils module instead.

Note that for the tool_wallet.py test, the used hash is changed from
sha1 to sha256, but as the only purpose is to detect file content
changes, this doesn't matter. Also, the optimization using `memoryview`
is overkill here, as the opened file has only a size of 24KiB and
determining the hash doesn't take longer than a few hundred
micro-seconds on my machine.

Author: theStack

test/functional/rpc_dumptxoutset.py

@@ -4,13 +4,15 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test the generation of UTXO snapshots using `dumptxoutset`.
 """
+from pathlib import Path
 
 from test_framework.blocktools import COINBASE_MATURITY
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import assert_equal, assert_raises_rpc_error
-
-import hashlib
-from pathlib import Path
+from test_framework.util import (
+    assert_equal,
+    assert_raises_rpc_error,
+    sha256sum_file,
+)
 
 
 class DumptxoutsetTest(BitcoinTestFramework):
@@ -39,11 +41,10 @@ def run_test(self):
             out['base_hash'],
             '09abf0e7b510f61ca6cf33bab104e9ee99b3528b371d27a2d4b39abb800fba7e')
 
-        with open(str(expected_path), 'rb') as f:
-            digest = hashlib.sha256(f.read()).hexdigest()
-            # UTXO snapshot hash should be deterministic based on mocked time.
-            assert_equal(
-                digest, 'b1bacb602eacf5fbc9a7c2ef6eeb0d229c04e98bdf0c2ea5929012cd0eae3830')
+        # UTXO snapshot hash should be deterministic based on mocked time.
+        assert_equal(
+            sha256sum_file(str(expected_path)).hex(),
+            'b1bacb602eacf5fbc9a7c2ef6eeb0d229c04e98bdf0c2ea5929012cd0eae3830')
 
         assert_equal(
             out['txoutset_hash'], '1f7e3befd45dc13ae198dfbb22869a9c5c4196f8e9ef9735831af1288033f890')

test/functional/tool_wallet.py

@@ -4,7 +4,6 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test bitcoin-wallet."""
 
-import hashlib
 import os
 import stat
 import subprocess
@@ -13,9 +12,10 @@
 from collections import OrderedDict
 
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import assert_equal
-
-BUFFER_SIZE = 16 * 1024
+from test_framework.util import (
+    assert_equal,
+    sha256sum_file,
+)
 
 
 class ToolWalletTest(BitcoinTestFramework):
@@ -54,12 +54,7 @@ def assert_tool_output(self, output, *args):
         assert_equal(p.poll(), 0)
 
     def wallet_shasum(self):
-        h = hashlib.sha1()
-        mv = memoryview(bytearray(BUFFER_SIZE))
-        with open(self.wallet_path, 'rb', buffering=0) as f:
-            for n in iter(lambda: f.readinto(mv), 0):
-                h.update(mv[:n])
-        return h.hexdigest()
+        return sha256sum_file(self.wallet_path).hex()
 
     def wallet_timestamp(self):
         return os.path.getmtime(self.wallet_path)