if(ApexPages.currentPage().getParameters().get('ScheduleFlag') == 'True'){
            schId = ApexPages.currentPage().getParameters().get('schId');
            schReport = [Select Id,Report_Name__c,Selected_Fields__c,Labels__c  from Schedule_Report__c where Id = :schId];
            allFields = schReport.Selected_Fields__c;
            allLabels = New List<string>();
            for(string lab :schReport.Labels__c.split(',')){
              allLabels.add(lab.trim());
            }
            ScheduleFlag = true;
            directSchedule = true;
            WeeklyFlag = true;
            userList = new list<SelectOption>();
            for(user usr : [SELECT Id,IsActive,Name,Email FROM User where IsActive = true]){
                userList.add(new SelectOption(usr.Email,usr.Name));
            }

            //Next4();
        }
    }

Test.setCurrentPage(Page.myVFPage);
ApexPages.currentPage().getParameters().put('ScheduleFlag','True');

MyController con = new MyController();
con.myMethodThatUsesParameter();

Test.setCurrentPage(Page.TestPage);
ApexPages.currentPage().getParameters().put('ScheduleFlag', 'True');