Merge bitcoin/bitcoin#25811: doc: test: suggest multi-line imports in functional test style guide

4edc6893825fd8c45c53c81c73a6a7801e1b458c doc: test: suggest multi-line imports in functional test style guide (Sebastian Falbesoner)

Pull request description:

  As long as I remember contributing to functional tests (~2-3 years), it was always kind of an unwritten rule that multi-line imports are preferred over single-line imports in order to reduce the possibility of potential merge conflicts -- at least if more than one symbol from a module is imported. This PR adds this rule to the style guide and adapts the example test accordingly. (Inspired by https://github.com/bitcoin/bitcoin/pull/25792#discussion_r941180819).

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Tree-SHA512: c7b6ff62f601f4e57cc8334d291662987d6737ebca8d81c063280409f4412302172f1404ec16afc9a13007bcdba55bdab66b9b80363287e287888929cb386584

test/functional/README.md

@@ -28,7 +28,9 @@ don't have test cases for.
   could lead to bugs and issues in the test code.
 - Use [type hints](https://docs.python.org/3/library/typing.html) in your code to improve code readability
   and to detect possible bugs earlier.
-- Avoid wildcard imports
+- Avoid wildcard imports.
+- If more than one name from a module is needed, use lexicographically sorted multi-line imports
+  in order to reduce the possibility of potential merge conflicts.
 - Use a module-level docstring to describe what the test is testing, and how it
   is testing it.
 - When subclassing the BitcoinTestFramework, place overrides for the

test/functional/example_test.py

@@ -14,8 +14,15 @@ is testing and *how* it's being tested
 from collections import defaultdict
 
 # Avoid wildcard * imports
-from test_framework.blocktools import (create_block, create_coinbase)
-from test_framework.messages import CInv, MSG_BLOCK
+# Use lexicographically sorted multi-line imports
+from test_framework.blocktools import (
+    create_block,
+    create_coinbase,
+)
+from test_framework.messages import (
+    CInv,
+    MSG_BLOCK,
+)
 from test_framework.p2p import (
     P2PInterface,
     msg_block,