Merge #19674: refactor: test: use throwaway _ variable for unused loop counters

dac7a111bdd3b0233d94cf68dae7a8bfc6ac9c64 refactor: test: use _ variable for unused loop counters (Sebastian Falbesoner)

Pull request description:

  This tiny PR substitutes Python loops in the form of `for x in range(N): ...` by `for _ in range(N): ...` where applicable. The idea is indicating to the reader that a block (or statement, in list comprehensions) is just repeated N times, and that the loop counter is not used in the body, hence using the throwaway variable. This is already done quite often in the current tests (see e.g. `$ git grep "for _ in range("`). Another alternative would be using `itertools.repeat` (according to Python core developer Raymond Hettinger it's [even faster](https://twitter.com/raymondh/status/1144527183341375488)), but that doesn't seem to be widespread in use and I'm not sure about a readability increase.

  The only drawback I see is that whenever one wants to debug loop iterations, one would need to introduce a loop variable again. Reviewing this is basically a no-brainer, since tests would fail immediately if a a substitution has taken place on a loop where the variable is used.

  Instances to replace were found by `$ git grep "for.*in range("` and manually checked.

ACKs for top commit:
  darosior:
    ACK dac7a111bdd3b0233d94cf68dae7a8bfc6ac9c64
  instagibbs:
    manual inspection ACK https://github.com/bitcoin/bitcoin/pull/19674/commits/dac7a111bdd3b0233d94cf68dae7a8bfc6ac9c64
  practicalswift:
    ACK dac7a111bdd3b0233d94cf68dae7a8bfc6ac9c64 -- the updated code is easier to reason about since the throwaway nature of a variable is expressed explicitly (using the Pythonic `_` idiom) instead of implicitly. Explicit is better than implicit was we all know by now :)

Tree-SHA512: 5f43ded9ce14e5e00b3876ec445b90acda1842f813149ae7bafa93f3ac3d510bb778e2c701187fd2c73585e6b87797bb2d2987139bd1a9ba7d58775a59392406

1 files changed, 2 insertions, 2 deletions

diff --git a/test/functional/wallet_descriptor.py b/test/functional/wallet_descriptor.py
index 289ccf43ec..9c63e8f7d3 100755
--- a/test/functional/wallet_descriptor.py
+++ b/test/functional/wallet_descriptor.py
@@ -107,7 +107,7 @@ class WalletDescriptorTest(BitcoinTestFramework):
         assert_equal(info2['desc'], info3['desc'])
 
         self.log.info("Test that getnewaddress still works after keypool is exhausted in an encrypted wallet")
-        for i in range(0, 500):
+        for _ in range(500):
             send_wrpc.getnewaddress()
 
         self.log.info("Test that unlock is needed when deriving only hardened keys in an encrypted wallet")
@@ -120,7 +120,7 @@ class WalletDescriptorTest(BitcoinTestFramework):
         }])
         send_wrpc.walletlock()
         # Exhaust keypool of 100
-        for i in range(0, 100):
+        for _ in range(100):
             send_wrpc.getnewaddress(address_type='bech32')
         # This should now error
         assert_raises_rpc_error(-12, "Keypool ran out, please call keypoolrefill first", send_wrpc.getnewaddress, '', 'bech32')