test: remove confusing MAX_BLOCK_BASE_SIZE

The constant `MAX_BLOCK_BASE_SIZE` has been removed from the
core implementation years ago due to being confusing and
superfluous, as it is implied by the block weight limit (see
PRs #10618 and #10608). Since there is also no point in
still keeping it in the functional test framework, we switch
to weight-based accounting on the relevant test code parts
and use `MAX_BLOCK_WEIGHT` instead for the block limit
checks.

test/functional/p2p_segwit.py

@@ -21,7 +21,7 @@ from test_framework.messages import (
     CTxInWitness,
     CTxOut,
     CTxWitness,
-    MAX_BLOCK_BASE_SIZE,
+    MAX_BLOCK_WEIGHT,
     MSG_BLOCK,
     MSG_TX,
     MSG_WITNESS_FLAG,
@@ -110,16 +110,6 @@ def sign_p2pk_witness_input(script, tx_to, in_idx, hashtype, value, key):
     tx_to.wit.vtxinwit[in_idx].scriptWitness.stack = [signature, script]
     tx_to.rehash()
 
-def get_virtual_size(witness_block):
-    """Calculate the virtual size of a witness block.
-
-    Virtual size is base + witness/4."""
-    base_size = len(witness_block.serialize(with_witness=False))
-    total_size = len(witness_block.serialize())
-    # the "+3" is so we round up
-    vsize = int((3 * base_size + total_size + 3) / 4)
-    return vsize
-
 def test_transaction_acceptance(node, p2p, tx, with_witness, accepted, reason=None):
     """Send a transaction to the node and check that it's accepted to the mempool
 
@@ -902,7 +892,7 @@ class SegWitTest(BitcoinTestFramework):
         block.solve()
 
         block.vtx[0].wit.vtxinwit[0].scriptWitness.stack.append(b'a' * 5000000)
-        assert get_virtual_size(block) > MAX_BLOCK_BASE_SIZE
+        assert block.get_weight() > MAX_BLOCK_WEIGHT
 
         # We can't send over the p2p network, because this is too big to relay
         # TODO: repeat this test with a block that can be relayed
@@ -911,7 +901,7 @@ class SegWitTest(BitcoinTestFramework):
         assert self.nodes[0].getbestblockhash() != block.hash
 
         block.vtx[0].wit.vtxinwit[0].scriptWitness.stack.pop()
-        assert get_virtual_size(block) < MAX_BLOCK_BASE_SIZE
+        assert block.get_weight() < MAX_BLOCK_WEIGHT
         assert_equal(None, self.nodes[0].submitblock(block.serialize().hex()))
 
         assert self.nodes[0].getbestblockhash() == block.hash
@@ -974,11 +964,10 @@ class SegWitTest(BitcoinTestFramework):
         child_tx.rehash()
         self.update_witness_block_with_transactions(block, [parent_tx, child_tx])
 
-        vsize = get_virtual_size(block)
-        additional_bytes = (MAX_BLOCK_BASE_SIZE - vsize) * 4
+        additional_bytes = MAX_BLOCK_WEIGHT - block.get_weight()
         i = 0
         while additional_bytes > 0:
-            # Add some more bytes to each input until we hit MAX_BLOCK_BASE_SIZE+1
+            # Add some more bytes to each input until we hit MAX_BLOCK_WEIGHT+1
             extra_bytes = min(additional_bytes + 1, 55)
             block.vtx[-1].wit.vtxinwit[int(i / (2 * NUM_DROPS))].scriptWitness.stack[i % (2 * NUM_DROPS)] = b'a' * (195 + extra_bytes)
             additional_bytes -= extra_bytes
@@ -987,8 +976,7 @@ class SegWitTest(BitcoinTestFramework):
         block.vtx[0].vout.pop()  # Remove old commitment
         add_witness_commitment(block)
         block.solve()
-        vsize = get_virtual_size(block)
-        assert_equal(vsize, MAX_BLOCK_BASE_SIZE + 1)
+        assert_equal(block.get_weight(), MAX_BLOCK_WEIGHT + 1)
         # Make sure that our test case would exceed the old max-network-message
         # limit
         assert len(block.serialize()) > 2 * 1024 * 1024
@@ -1001,7 +989,7 @@ class SegWitTest(BitcoinTestFramework):
         block.vtx[0].vout.pop()
         add_witness_commitment(block)
         block.solve()
-        assert get_virtual_size(block) == MAX_BLOCK_BASE_SIZE
+        assert block.get_weight() == MAX_BLOCK_WEIGHT
 
         test_witness_block(self.nodes[0], self.test_node, block, accepted=True)
 
@@ -1727,7 +1715,7 @@ class SegWitTest(BitcoinTestFramework):
             block.vtx.append(tx)
 
             # Test the block periodically, if we're close to maxblocksize
-            if (get_virtual_size(block) > MAX_BLOCK_BASE_SIZE - 1000):
+            if block.get_weight() > MAX_BLOCK_WEIGHT - 4000:
                 self.update_witness_block_with_transactions(block, [])
                 test_witness_block(self.nodes[0], self.test_node, block, accepted=True)
                 block = self.build_next_block()