# createReplayClient (/docs/api/core-testing/functions/createReplayClient)



```ts
function createReplayClient(lines): SystemOneClient;
```

Answers the line whose `request` is deep-equal to the incoming one. Key order is free.

## Parameters [#parameters]

| Parameter | Type                                                                       |
| --------- | -------------------------------------------------------------------------- |
| `lines`   | readonly [`ReplayLine`](/docs/api/core-testing/type-aliases/ReplayLine)\[] |

## Returns [#returns]

[`SystemOneClient`](/docs/api/core/interfaces/SystemOneClient)