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

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dac7a111bd 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 dac7a111bd
  instagibbs:
    manual inspection ACK dac7a111bd
  practicalswift:
    ACK dac7a111bd -- 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
This commit is contained in:
fanquake
2020-08-11 08:50:34 +08:00
parent 85fa648c85 dac7a111bd
commit cb1ee1551c
35 changed files with 83 additions and 83 deletions
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16
test/functional/p2p_segwit.py
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@ -947,7 +947,7 @@ class SegWitTest(BitcoinTestFramework):
parent_tx = CTransaction()
parent_tx.vin.append(CTxIn(prevout, b""))
child_value = int(value / NUM_OUTPUTS)
for i in range(NUM_OUTPUTS):
for _ in range(NUM_OUTPUTS):
parent_tx.vout.append(CTxOut(child_value, script_pubkey))
parent_tx.vout[0].nValue -= 50000
assert parent_tx.vout[0].nValue > 0
@ -957,7 +957,7 @@ class SegWitTest(BitcoinTestFramework):
for i in range(NUM_OUTPUTS):
child_tx.vin.append(CTxIn(COutPoint(parent_tx.sha256, i), b""))
child_tx.vout = [CTxOut(value - 100000, CScript([OP_TRUE]))]
for i in range(NUM_OUTPUTS):
for _ in range(NUM_OUTPUTS):
child_tx.wit.vtxinwit.append(CTxInWitness())
child_tx.wit.vtxinwit[-1].scriptWitness.stack = [b'a' * 195] * (2 * NUM_DROPS) + [witness_program]
child_tx.rehash()
@ -1204,7 +1204,7 @@ class SegWitTest(BitcoinTestFramework):
tx = CTransaction()
tx.vin.append(CTxIn(COutPoint(self.utxo[0].sha256, self.utxo[0].n), b""))
value = self.utxo[0].nValue
for i in range(10):
for _ in range(10):
tx.vout.append(CTxOut(int(value / 10), script_pubkey))
tx.vout[0].nValue -= 1000
assert tx.vout[0].nValue >= 0
@ -1382,7 +1382,7 @@ class SegWitTest(BitcoinTestFramework):
tx = CTransaction()
tx.vin.append(CTxIn(COutPoint(self.utxo[0].sha256, self.utxo[0].n), b""))
split_value = (self.utxo[0].nValue - 4000) // NUM_SEGWIT_VERSIONS
for i in range(NUM_SEGWIT_VERSIONS):
for _ in range(NUM_SEGWIT_VERSIONS):
tx.vout.append(CTxOut(split_value, CScript([OP_TRUE])))
tx.rehash()
block = self.build_next_block()
@ -1664,7 +1664,7 @@ class SegWitTest(BitcoinTestFramework):
tx = CTransaction()
tx.vin.append(CTxIn(COutPoint(prev_utxo.sha256, prev_utxo.n), b""))
split_value = prev_utxo.nValue // NUM_SIGHASH_TESTS
for i in range(NUM_SIGHASH_TESTS):
for _ in range(NUM_SIGHASH_TESTS):
tx.vout.append(CTxOut(split_value, script_pubkey))
tx.wit.vtxinwit.append(CTxInWitness())
sign_p2pk_witness_input(witness_program, tx, 0, SIGHASH_ALL, prev_utxo.nValue, key)
@ -1694,7 +1694,7 @@ class SegWitTest(BitcoinTestFramework):
tx.wit.vtxinwit.append(CTxInWitness())
total_value += temp_utxos[i].nValue
split_value = total_value // num_outputs
for i in range(num_outputs):
for _ in range(num_outputs):
tx.vout.append(CTxOut(split_value, script_pubkey))
for i in range(num_inputs):
# Now try to sign each input, using a random hashtype.
@ -1992,7 +1992,7 @@ class SegWitTest(BitcoinTestFramework):
split_value = self.utxo[0].nValue // outputs
tx = CTransaction()
tx.vin.append(CTxIn(COutPoint(self.utxo[0].sha256, self.utxo[0].n), b""))
for i in range(outputs):
for _ in range(outputs):
tx.vout.append(CTxOut(split_value, script_pubkey))
tx.vout[-2].scriptPubKey = script_pubkey_toomany
tx.vout[-1].scriptPubKey = script_pubkey_justright
@ -2078,7 +2078,7 @@ class SegWitTest(BitcoinTestFramework):
if (len(tx.wit.vtxinwit) != len(tx.vin)):
# vtxinwit must have the same length as vin
tx.wit.vtxinwit = tx.wit.vtxinwit[:len(tx.vin)]
for i in range(len(tx.wit.vtxinwit), len(tx.vin)):
for _ in range(len(tx.wit.vtxinwit), len(tx.vin)):
tx.wit.vtxinwit.append(CTxInWitness())
r += tx.wit.serialize()
r += struct.pack("<I", tx.nLockTime)