Merge #17502: test: add unit test for non-standard bare multisig txs

1bb5d51 test: add unit test for non-standard bare multisig txs (Sebastian Falbesoner)

Pull request description:

  Approaches another missing unit test of issue #17394: Checks that the function `IsStandardTx()` returns rejection reason `"bare-multisig"` if any one of the outputs' scriptPubKey has bare multisignature format (i.e. `M <PubKey1> <PubKey2> ... <PubKeyN> N OP_CHECKSIG`, not P2SH!) and the policy flag `fIsBareMultisigStd` is set to false.

ACKs for top commit:
  instagibbs:
    utACK bitcoin/bitcoin@1bb5d51

Tree-SHA512: d7c95e35da16520d6dcd2b4278e2426fedd13f68d1f23c90e85e929774e123fbfcfbccc26df6ad1c0dd61780896fa4b4b3d4e8280c647bb06df2bfcf2ba572fb

Author: MarcoFalke

src/test/transaction_tests.cpp

@@ -820,6 +820,17 @@ BOOST_AUTO_TEST_CASE(test_IsStandard)
     reason.clear();
     BOOST_CHECK(!IsStandardTx(CTransaction(t), reason));
     BOOST_CHECK_EQUAL(reason, "scriptsig-size");
+
+    // Check bare multisig (standard if policy flag fIsBareMultisigStd is set)
+    fIsBareMultisigStd = true;
+    t.vout[0].scriptPubKey = GetScriptForMultisig(1, {key.GetPubKey()}); // simple 1-of-1
+    t.vin[0].scriptSig = CScript() << std::vector<unsigned char>(65, 0);
+    BOOST_CHECK(IsStandardTx(CTransaction(t), reason));
+
+    fIsBareMultisigStd = false;
+    reason.clear();
+    BOOST_CHECK(!IsStandardTx(CTransaction(t), reason));
+    BOOST_CHECK_EQUAL(reason, "bare-multisig");
 }
 
 BOOST_AUTO_TEST_SUITE_END()