How to Mock r2dbcEntityTemplate.getDatabaseClient().sql method in DaoImpl for Unit Test

Question

I want to Mock the r2dbcEntityTemplate and Unit Test the DaoImpl class.

I have the DaoImpl class with definition:

public class StudentDaoImpl implements StudentDao{

private final R2dbcEntityTemplate r2dbcEntityTemplate;

@Override
  public Mono<Student> upsert(Student student) {

    return r2dbcEntityTemplate
        .getDatabaseClient()
        .sql(DaoUtil.UPSERT_QUERY)
        .bind("student_id", student.getStudentId())
        .bind("name", student.getName())
        .bind("roll", student.getRoll())
        .map(DaoUtil.STUDENT_MAPPING_FUNCTION)
        .one();
  }

}

Dao Class:

public interface StudentDao {
  Mono<Student> upsert(Student student);
}

and DaoUtil class:

public class DaoUtil{
public static final String UPSERT_QUERY = "INSERT INTO \n "
          + "student \n"
          + "  (student_id, \n "
          + "  name, \n"
          + "  roll) \n"
          + "  VALUES \n"
          + "  (:student_id, \n"
          + "  :name, \n"
          + "  :roll) \n"
          + "   ON CONFLICT \n"
          + "   (student_id, \n"
          + "   name) \n"
          + "   DO UPDATE SET \n"
          + "   roll = \n"
          + "   excluded.roll"
          + "   RETURNING *;";

public static final Function<Row, Student>
      STUDENT_MAPPING_FUNCTION =
          row ->
             Student.builder()
                  .id(row.get("id", Long.class))
                  .studentId(row.get("student_id", String.class))
                  .name(row.get("name", String.class))
                  .roll(row.get("roll", String.class))
                  .build();


}

I am not finding correct Constructors to mock the r2dbcEntityTemplate

Please guide me to a suitable example for this usecause.

Thanks in advance.