Node.js express-Unit Testing of a function-the function reads a csv file and store its data in MySQL database

Node.js express-Unit Testing of a function-the function reads a csv file and store its data in MySQL database
My function that is to be tested. I want to test uploadAuthors function using Jest
```
const uploadAuthors = async (req, res) => {
  try {
    if (req.file == undefined) {
      return res.status(400).send("Please upload a CSV file!");
    }
    let authors = [];
    let path = __basedir + "/resources/static/assets/uploads/" + req.file.filename;
    fs.createReadStream(path)
      .pipe(csv.parse({ headers: true }))
      .on("error", (error) => {
        throw error.message;
      })
      .on("data", (row) => {
        authors.push(row);
      })
      .on("end", () => {
        Authors.bulkCreate(authors)
          .then(() => {
            res.status(200).send({
              message:
                "Uploaded the file successfully: " + req.file.originalname,
            });
          })
          .catch((error) => {
            res.status(500).send({
              message: "Fail to import data into database!",
              error: error.message,
            });
          });
      });
  } catch (error) {
    console.log(error);
    res.status(500).send({
      message: "Could not upload the file: " + req.file.originalname,
    });
  }
};```

Here's the csv file data
email,firstname,lastname
null-walter@echocat.org,Paul,Walter

And here's my Unit Test file's code:
```
const { uploadAuthors } = require('../controllers/csv')
global.__basedir = __dirname + "/Raft-Labs-Test/..";




beforeEach(() => {
    //code to connect to database
});

test('Uploading data to authors table', async () => {
    let resultData = {"message": "Uploaded the file successfully: test.csv"}
    let req = {file: test.csv}
    let res = {}

    let data = await uploadAuthors(req,res)
    expect(data).toEqual(resultData) 
})```

I want to write test using jest for the above function but just cannot do it without having a req.file (In the test's code test.csv file inside req object is just a variable and not the actual file) which is fine to have using Postman but i don't know how to do it without Postman and through Jest.