testing dynamodb functionality with jest - jestjs

Question

I have a file in my typescript/node project that contains a function to retrieve an item from a dynamodb table as follows:
import { DynamoDBClient, GetItemCommand } from "#aws-sdk/client-dynamodb";
import { companyInterface } from './companyInterface';
import { marshall, unmarshall } from '#aws-sdk/util-dynamodb'
const client = new DynamoDBClient({ region: `${process.env.AWS_REGION}` });
export const retrieveItem = async (id: string): Promise<companyInterface> => {
const cmd = new GetItemCommand({
ConsistentRead: true,
Key: marshall({
id,
}),
TableName: 'testTable',
});
const retrievedItem = await client.send(cmd);
return unmarshall(retrievedItem.Item) as companyInterface;
};
I wish to write a unit test (the project uses jest) that can test whether this retrieveItem function will return items in a specific form (the companyInterface). The documentation at https://jestjs.io/docs/dynamodb says I have to include the following code to connect to a test local database:
const {DocumentClient} = require('aws-sdk/clients/dynamodb');
const isTest = process.env.JEST_WORKER_ID;
const config = {
convertEmptyValues: true,
...(isTest && {
endpoint: 'localhost:8000',
sslEnabled: false,
region: 'local-env',
}),
};
const ddb = new DocumentClient(config);
However, this documentation doesn't seem to lead to information on how to use my custom functions (specifically the retrieveItem), since they are passing the config object to a new DocumentClient. Does anyone know how to specifically test my function with jest, such that I can test whether my function returns items with a specific form/having certain properties?