ZergyPoo

public virtual class DemoMapper {

    @TestVisible
    private static DemoMapper instance;

    protected DemoMapper() {}

    public static DemoMapper getInstance() {
        if (instance != null) {
            return instance;

ZergyPoo

public class OrderBy {

        @TestVisible
        private String orderDirection;

        private String fieldName;

        public OrderBy(String orderDirection, String fieldName) {
            this.orderDirection = orderDirection;
            this.fieldName = fieldName;