test(fast-inbox): seed the inbox before the checkpoint's L1 block in propose harnesses (A-1384)

Both propose harnesses warped to the checkpoint's timestamp and only then sent their
L1-to-L2 messages, so the checkpoint referenced a bucket still accumulating in the
same L1 block. Propose rejects that reference: the snapshot could still be overwritten
in place. Sending the messages first puts them in an earlier L1 block, which is what
the sequencer does anyway, since it never selects a bucket younger than the inbox lag.

Author: spalladino

l1-contracts/test/base/RollupBase.sol

@@ -165,10 +165,12 @@ contract RollupBase is DecoderBase {
 
     checkpointFees[full.checkpoint.checkpointNumber] = _manaUsed * minFee;
 
-    // We jump to the time of the block. (unless it is in the past)
-    vm.warp(max(block.timestamp, Timestamp.unwrap(full.checkpoint.header.timestamp)));
-
+    // Seed the Inbox before jumping to the checkpoint's L1 block: propose rejects a bucket that is still
+    // accumulating, and a bucket keeps accumulating for the whole L1 block that opened it.
     _populateInbox(full.populate.sender, full.populate.recipient, full.populate.l1ToL2Content);
+
+    // We jump to the time of the block, always past the L1 block the messages above landed in.
+    vm.warp(max(block.timestamp + 1, Timestamp.unwrap(full.checkpoint.header.timestamp)));
     // Legacy frontier root for the header's inHash field. Unchecked at propose post-flip, but kept because the
     // fixtures were generated with it as part of the header hash.
     full.checkpoint.header.inHash = rollup.getInbox().getRoot(full.checkpoint.checkpointNumber);

l1-contracts/test/validator-selection/ValidatorSelection.t.sol

@@ -531,11 +531,13 @@ contract ValidatorSelectionTest is ValidatorSelectionTestBase {
     DecoderBase.Full memory full = load(_name);
     ProposedHeader memory header = full.checkpoint.header;
 
-    // We jump to the time of the block. (unless it is in the past)
-    vm.warp(max(block.timestamp, Timestamp.unwrap(full.checkpoint.header.timestamp)));
-
+    // Seed the Inbox before jumping to the checkpoint's L1 block: propose rejects a bucket that is still
+    // accumulating, and a bucket keeps accumulating for the whole L1 block that opened it.
     _populateInbox(full.populate.sender, full.populate.recipient, full.populate.l1ToL2Content);
 
+    // We jump to the time of the block, always past the L1 block the messages above landed in.
+    vm.warp(max(block.timestamp + 1, Timestamp.unwrap(full.checkpoint.header.timestamp)));
+
     rollup.setupEpoch();
 
     ree.proposer = rollup.getCurrentProposer();