How to test the library methods with JEST? Like firestore()

[ildaneta]

I'm going crazy trying to test methods like collections, but I can't test it, could someone help me please?

export const checkExistingPhoneNumberUsersCollectionFS = async (
    phoneNumber: string,
): Promise<IUserData[] | []> => {

    const snapshot = await firestore()
      .collection('users')
      .where('phone_number', '==', phoneNumber)
      .get();

    if (instant.empty) {
      return [];
    } other {
      const data = snapshot.docs.map(doc => {
        const {
          uid,
          phone number,
          device_uuid,
          Device Information,
          is_notifications_accepted,
        } = doc.data() as FirebaseFirestoreTypes.DocumentData;

        turn back {
          uid,
          device_uuid,
          phone number,
          Device Information,
          is_notifications_accepted,
        };
      });

      return data;
    }
};

This is the method that checks within the user collection if the number passed exists.