JUnit && Mockito

Question

I have this method that I want to test

     private Connection con;
     private Statement set;
     private ResultSet rs;

     public void actualizarJugador(String nombre) {
            try {
                set = con.createStatement();
                set.executeUpdate("UPDATE Jugadores SET votos=votos+1 WHERE nombre " + " LIKE '%" + nombre + "%'");
                rs.close();
                set.close();
            } catch (Exception e) {
                // No modifica la tabla
                System.out.println("No modifica la tabla");
                System.out.println("El error es: " + e.getMessage());
            }
        }

How can I do it? How can I test a method that does not return anything?

Thanks

Answer 1

the method has a side effect, it changes the calue of votos under a certain condition. To test that, you need to query your database and check that the value was actually updated. You can also check that values not fulfilling the where-condition are not updated. To do that you should query the database before and after you call your method, and compare the values with each other.

Answer 2

I have this example code

import java.sql.*;

public class ModeloDatos {

    private Connection con;
    private Statement set;
    private ResultSet rs;

    public void abrirConexion() {

        try {
            Class.forName("com.mysql.cj.jdbc.Driver");

            // Con variables de entorno
            String dbHost = System.getenv().get("DATABASE_HOST");
            String dbPort = System.getenv().get("DATABASE_PORT");
            String dbName = System.getenv().get("DATABASE_NAME");
            String dbUser = System.getenv().get("DATABASE_USER");
            String dbPass = System.getenv().get("DATABASE_PASS");

            String url = dbHost + ":" + dbPort + "/" + dbName;
            con = DriverManager.getConnection(url, dbUser, dbPass);

        } catch (Exception e) {
            // No se ha conectado
            System.out.println("No se ha podido conectar");
            System.out.println("El error es: " + e.getMessage());
        }
    }

    public boolean existeJugador(String nombre) {
        boolean existe = false;
        String cad;
        try {
            set = con.createStatement();
            rs = set.executeQuery("SELECT * FROM Jugadores");
            while (rs.next()) {
                cad = rs.getString("Nombre");
                cad = cad.trim();
                if (cad.compareTo(nombre.trim()) == 0) {
                    existe = true;
                }
            }
            rs.close();
            set.close();
        } catch (Exception e) {
            // No lee de la tabla
            System.out.println("No lee de la tabla");
            System.out.println("El error es: " + e.getMessage());
        }
        return (existe);
    }

    public void actualizarJugador(String nombre) {
        try {
            set = con.createStatement();
            set.executeUpdate("UPDATE Jugadores SET votos=votos+1 WHERE nombre " + " LIKE '%" + nombre + "%'");
            rs.close();
            set.close();
        } catch (Exception e) {
            // No modifica la tabla
            System.out.println("No modifica la tabla");
            System.out.println("El error es: " + e.getMessage());
        }
    }

    public void insertarJugador(String nombre) {
        try {
            set = con.createStatement();
            set.executeUpdate("INSERT INTO Jugadores " + " (nombre,votos) VALUES ('" + nombre + "',1)");
            rs.close();
            set.close();
        } catch (Exception e) {
            // No inserta en la tabla
            System.out.println("No inserta en la tabla");
            System.out.println("El error es: " + e.getMessage());
        }
    }

    public void ponerVotosCero() {
        try {
            set = con.createStatement();
            set.executeUpdate("UPDATE Jugadores SET votos=0 where votos>0");
            rs.close();
            set.close();
        } catch (Exception e) {
            // No modifica la tabla
            System.out.println("Poner votos a cero. No modifica la tabla");
            System.out.println("El error es: " + e.getMessage());
        }
    }


    public void cerrarConexion() {
        try {
            con.close();
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }

}

With this test, it should be something similar

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;

public class ModeloDatosTest {
    @Test
    public void testExisteJugador() {
        System.out.println("Prueba de existeJugador");
        String nombre = "";
        ModeloDatos instance = new ModeloDatos();
        boolean expResult = false;
        boolean result = instance.existeJugador(nombre);
        assertEquals(expResult, result);
        //fail("Fallo forzado.");
    }
}