feat: Handle multiple blocks per slot in timetable

Also includes a refactor of the sequencer, checkpoint proposal job, and
timetable unit tests, as well as a README with how block building works
now within a slot.

Author: spalladino

yarn-project/archiver/src/test/mock_l2_block_source.ts

@@ -10,6 +10,7 @@ import type { AztecAddress } from '@aztec/stdlib/aztec-address';
 import {
   L2Block,
   L2BlockHash,
+  L2BlockNew,
   type L2BlockSource,
   type L2Tips,
   PublishedL2Block,
@@ -105,6 +106,16 @@ export class MockL2BlockSource implements L2BlockSource, ContractDataSource {
     return Promise.resolve(this.l2Blocks[number - 1]);
   }
 
+  /**
+   * Gets an L2 block (new format).
+   * @param number - The block number to return.
+   * @returns The requested L2 block.
+   */
+  public getL2BlockNew(number: BlockNumber): Promise<L2BlockNew | undefined> {
+    const block = this.l2Blocks[number - 1];
+    return Promise.resolve(block?.toL2Block());
+  }
+
   /**
    * Gets up to `limit` amount of L2 blocks starting from `from`.
    * @param from - Number of the first block to return (inclusive).

yarn-project/end-to-end/src/e2e_block_building.test.ts

@@ -101,9 +101,11 @@ describe('e2e_block_building', () => {
       // This will leave the sequencer with just a few seconds to build the block, so it shouldn't
       // be able to squeeze in more than a few txs in each. This is sensitive to the time it takes
       // to pick up and validate the txs, so we may need to bump it to work on CI.
-      jest
-        .spyOn(sequencer.sequencer.timetable, 'getProposerExecTimeEnd')
-        .mockImplementation((secondsIntoSlot: number) => secondsIntoSlot + 1);
+      jest.spyOn(sequencer.sequencer.timetable, 'canStartNextBlock').mockImplementation((secondsIntoSlot: number) => ({
+        canStart: true,
+        deadline: secondsIntoSlot + 1, // Give only 1 second for building
+        isLastBlock: true,
+      }));
 
       // Flood the mempool with TX_COUNT simultaneous txs
       const methods = times(TX_COUNT, i => contract.methods.increment_public_value(ownerAddress, i));