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# Control Mining and Time

## Overview

Mining Actions make block production deterministic. Pause automatic mining to inspect pending
transactions, mine an exact number of blocks, or advance time to test expiries and time locks.

## Recipes

These recipes assume you have [set up an Anvil Client](/docs/guides/testing/anvil).

### Mine on Demand

Disable automining, broadcast an operation, then use [`block.mine`](/docs/actions/test/block/mine)
to include it in a new block.

:::code-group
```ts twoslash [example.ts]
import { Value } from 'viem/utils'
import { client } from './viem.config'

await client.block.setAutomine({ enabled: false }) // [!code focus]

try {
  const hash = await client.transaction.send({ // [!code focus]
    to: '0x70997970c51812dc3a010c7d01b50e0d17dc79c8', // [!code focus]
    value: Value.fromEther('1'), // [!code focus]
  }) // [!code focus]
  await client.block.mine({ blocks: 1 }) // [!code focus]
} finally {
  await client.block.setAutomine({ enabled: true }) // [!code focus]
}
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/test.config.ts:setup]
```
:::

### Advance Time

Use [`block.increaseTime`](/docs/actions/test/block/increaseTime) to move the node clock forward,
then mine a block to make the new time observable onchain.

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

await client.block.increaseTime({ seconds: 60 * 60 }) // [!code focus]
await client.block.mine({ blocks: 1 }) // [!code focus]
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/test.config.ts:setup]
```
:::

### Set the Next Block Timestamp

Use [`block.setNextTimestamp`](/docs/actions/test/block/setNextTimestamp) when a test needs one exact
Unix timestamp.

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

await client.block.setNextTimestamp({ timestamp: 2_000_000_000n }) // [!code focus]
await client.block.mine({ blocks: 1 }) // [!code focus]
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/test.config.ts:setup]
```
:::

### Mine at an Interval

Use [`block.setIntervalMining`](/docs/actions/test/block/setIntervalMining) to produce blocks at a
fixed interval while testing polling or subscription behavior.

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

await client.block.setAutomine({ enabled: false }) // [!code focus]
await client.block.setIntervalMining({ interval: 2 }) // [!code focus]

// After the interval-mining assertion:
await client.block.setIntervalMining({ interval: 0 }) // [!code focus]
await client.block.setAutomine({ enabled: true }) // [!code focus]
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/test.config.ts:setup]
```
:::

### Customize the Next Block

Use [`block.setCoinbase`](/docs/actions/test/block/setCoinbase),
[`block.setGasLimit`](/docs/actions/test/block/setGasLimit), and
[`block.setNextBaseFeePerGas`](/docs/actions/test/block/setNextBaseFeePerGas) to exercise contracts
whose behavior depends on block fields.

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

const id = await client.state.snapshot()

try {
  await client.block.setCoinbase({ // [!code focus]
    address: '0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266', // [!code focus]
  }) // [!code focus]
  await client.block.setGasLimit({ gasLimit: 30_000_000n }) // [!code focus]
  await client.block.setNextBaseFeePerGas({ // [!code focus]
    baseFeePerGas: 1_000_000_000n, // [!code focus]
  }) // [!code focus]
  await client.block.mine({ blocks: 1 }) // [!code focus]
} finally {
  await client.state.revert({ id })
}
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/test.config.ts:setup]
```
:::

## Best Practices

### Restore Mining Settings

Re-enable automining and clear interval settings after each test. Leaked node settings make later
tests order-dependent.

### Assert Onchain Time

Read the resulting block timestamp instead of comparing only with the host clock. The node controls
the timestamp contracts observe.

## See More

<Cards>
  <Card icon="lucide:list-ordered" title="Inspect the Transaction Pool" description="Observe transactions while automatic mining is paused." to="/docs/guides/testing/txpool" />

  <Card icon="lucide:undo-2" title="Snapshot and Restore" description="Reset mining and state changes between tests." to="/docs/guides/testing/snapshots" />
</Cards>