Classe Login com acesso ao Banco de Dados

LoginDAO.java

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;

public class LoginDAO implements ILoginDAO {

	static Connection conexao;
	
	public LoginDAO(Connection conexaoBD) {
		this.conexao = conexaoBD;
	}

	public boolean consultar(String paramUsuario, String paramSenha) throws SQLException {
		try {
			PreparedStatement pstmt = conexao.prepareStatement("select * from Login where usuario ='"+paramUsuario+"' and senha ='"+paramSenha+"'");
			
			ResultSet rs = pstmt.executeQuery();
			
			String nome = null;
			String senha = null;
			
			while(rs.next()) {
				nome = rs.getString("usuario");
				senha = rs.getString("senha");
			}
			
			if(nome != null && senha != null) {
				return true;
			}
			else {
				return false;
			}
		} catch(SQLException e) {
            System.out.println("Erro = "+e.getMessage());
            return false;
		}
	}

	 //Posso passar uma query que não retorna nada (insert, update, delete)
    public static boolean executa(String sql){
       
        Statement stmt = null;
       
        try{
            stmt = conexao.createStatement();
            stmt.executeUpdate(sql);        }
        catch(Exception e){
            System.out.println("Erro = "+e.getMessage());
            return false;
        }
        return true;
    }
	
	
	@Override
	public ResultSet listar() throws SQLException {
		try {
			PreparedStatement pstmt = conexao.prepareStatement("select * from Login");
			
			ResultSet rs = pstmt.executeQuery();
			
			return rs;
		} catch(SQLException e) {
            System.out.println("Erro = "+e.getMessage());
            return null;
		}
	}
}

LoginDAOTest.java

import static org.junit.Assert.*;

import java.sql.Connection;

import org.junit.Test;

import junit.framework.TestCase;


public class LoginDAOTest extends TestCase {

	@Test
	public void testDeveriaRetornarTrueSeLoginSenhaValidos() throws Exception {
		Connection conexaoBD;
		
		IConexao conexao = new ConexaoMySQL("admin", "admin");
		conexaoBD = conexao.getConexao();

		LoginDAO login = new LoginDAO(conexaoBD);
		
		assertTrue(login.executa("insert into Login(usuario, senha) values ('teste','123atest')"));
		assertTrue(login.consultar("teste","123atest"));
		assertTrue(login.executa("delete from Login where usuario = 'teste'"));
	}
	
	
	@Test
	public void testDeveriaInserirUsuario() throws Exception {
		Connection conexaoBD;
		
		IConexao conexao = new ConexaoMySQL("admin", "admin");
		conexaoBD = conexao.getConexao();
	
		LoginDAO login = new LoginDAO(conexaoBD);
		
		assertTrue(login.executa("insert into Login(usuario, senha) values ('aaaa','bbbb')"));
		assertTrue(login.consultar("aaaa", "bbbb"));
		assertTrue(login.executa("delete from Login where usuario = 'aaaa'"));
	}
	
	@Test
	public void testDeveriaExcluirUsuario() throws Exception {
		Connection conexaoBD;
		
		IConexao conexao = new ConexaoMySQL("admin", "admin");
		conexaoBD = conexao.getConexao();
	
		LoginDAO login = new LoginDAO(conexaoBD);
		
		assertTrue(login.executa("delete from Login where usuario = 'teste'"));
	}
}