Merge bitcoin/bitcoin#22846: policy: unit test Segwit dust thresholds

97cea1a93a policy: unit test Segwit dust thresholds (Antoine Poinsot)

Pull request description:

  This is the unit testing part of #22779, hence without the threshold modification.

ACKs for top commit:
  MarcoFalke:
    cr ACK 97cea1a93a
  benthecarman:
    crACK 97cea1a93a

Tree-SHA512: 96fb194709ae44364455eb920ed3ecff2e11e5327e0a72b9eeec9f9445894302099a0c4ffb1e0c8d4d523c0bfe06c57f1ebb0c03cf3389a73f518e3b174c45aa

src/test/transaction_tests.cpp

@@ -955,6 +955,33 @@ BOOST_AUTO_TEST_CASE(test_IsStandard)
     BOOST_CHECK(!IsStandardTx(CTransaction(t), reason));
     BOOST_CHECK_EQUAL(reason, "bare-multisig");
     fIsBareMultisigStd = DEFAULT_PERMIT_BAREMULTISIG;
+
+    // Check P2WPKH outputs dust threshold
+    t.vout[0].scriptPubKey = CScript() << OP_0 << ParseHex("ffffffffffffffffffffffffffffffffffffffff");
+    t.vout[0].nValue = 294;
+    BOOST_CHECK(IsStandardTx(CTransaction(t), reason));
+    t.vout[0].nValue = 293;
+    BOOST_CHECK(!IsStandardTx(CTransaction(t), reason));
+    BOOST_CHECK_EQUAL(reason, "dust");
+
+    // Check P2WSH outputs dust threshold
+    t.vout[0].scriptPubKey = CScript() << OP_0 << ParseHex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");
+    t.vout[0].nValue = 330;
+    BOOST_CHECK(IsStandardTx(CTransaction(t), reason));
+    t.vout[0].nValue = 329;
+    BOOST_CHECK(!IsStandardTx(CTransaction(t), reason));
+    BOOST_CHECK_EQUAL(reason, "dust");
+
+    // Check future Witness Program versions dust threshold
+    for (int op = OP_2; op <= OP_16; op += 1) {
+        t.vout[0].scriptPubKey = CScript() << (opcodetype)op << ParseHex("ffff");
+        t.vout[0].nValue = 240;
+        BOOST_CHECK(IsStandardTx(CTransaction(t), reason));
+
+        t.vout[0].nValue = 239;
+        BOOST_CHECK(!IsStandardTx(CTransaction(t), reason));
+        BOOST_CHECK_EQUAL(reason, "dust");
+    }
 }
 
 BOOST_AUTO_TEST_SUITE_END()