Custom Blocks

You can force-produce blocks using the produceBlocks helper to achieve an arbitrary block height. This is especially useful when you want to do some testing regarding transaction maturity.

import { DateTime } from 'fuels';
import { launchTestNode } from 'fuels/test-utils';

using launched = await launchTestNode();
const { provider } = launched;
const block = await provider.getBlock('latest');
if (!block) {
  throw new Error('No latest block');
}
const { time: timeLastBlockProduced } = block;

const producedBlockHeight = await provider.produceBlocks(3);

const producedBlock = await provider.getBlock(producedBlockHeight.toNumber());

const oldest = DateTime.fromTai64(timeLastBlockProduced);
const newest = DateTime.fromTai64(producedBlock!.time);
// newest >= oldest
console.assert(producedBlock, 'No latest block');
console.assert(newest >= oldest, 'Newest block is not greater or equal to oldest block');

See code in context

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Blocks With Custom Timestamps

You can also produce blocks with a custom block time using the produceBlocks helper by specifying the second optional parameter.

using launchedWithCustomTimestamp = await launchTestNode();
const { provider: providerWithCustomTimestamp } = launchedWithCustomTimestamp;

const latestBlock = await providerWithCustomTimestamp.getBlock('latest');
if (!latestBlock) {
  throw new Error('No latest block');
}
const latestBlockTimestamp = DateTime.fromTai64(latestBlock.time).toUnixMilliseconds();
const newBlockHeight = await providerWithCustomTimestamp.produceBlocks(
  3,
  latestBlockTimestamp + 1000
);

console.assert(
  newBlockHeight.toHex() === latestBlock.height.add(3).toHex(),
  'New block height is not equal to latest block height + 3'
);

See code in context

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Full Example

For a full example, see the following file: <<< @/../../docs-snippets2/src/testing/tweaking-the-blockchain.ts#full