MongoDB adding `test` database while execution

Question

I'm trying to figure out why my MongoDB connection is not connecting me to a particular database.

My connection string is mongodb://localhost:27017/ Meanwhile, I'm trying to execute the script somehow it appends database test.

Here is my code from env.ts:

const PRIMARY_DB_URI = process.env.PRIMARY_DB_URI || 'mongodb://localhost:27017/'

credentials: PRIMARY_DB_URI + '?socketTimeoutMS=360000&connectTimeoutMS=360000'

connection.ts:

export const fortisConnection = mongoose.createConnection(
  database.credentials!
)
fortisConnection.on('connected', () => {
  console.log(mongoose.connections)
})

I need to extract data from mongodb://localhost:27017/ but have such a log.

 name: 'test',
    host: 'localhost',
    port: 27017,
    user: undefined,
    pass: undefined,
    client: MongoClient {
      _events: [Object: null prototype],
      _eventsCount: 1,
      _maxListeners: undefined,
      s: [Object],
      topology: [Server],
      [Symbol(kCapture)]: false
    },

Field name states for database name.

When I'm trying to connect to a particular database like: mongodb://localhost:27017/data

It does not connect to database data and asks to return some users as shown below, it does not return anything.

script:

async function test() {
    try {
        const user = await User.find()
        console.log(1, ' USER: ', user)
    } catch(e) {
        console.log(' error: ', e)
    }
}

Question: why it appends test to the database connection string?