@isTest static void testCreateSchedule() {

    // Create Revenue Pipeline record
    Revenue_Pipeline__c revPipe = new Revenue_Pipeline__c();
        revPipe.Weighted_Product_Price__c = 1200;
        revPipe.Product_Start_Date__c = date.newInstance(2016, 08, 1);
        revPipe.Product_End_Date__c = date.newInstance(2017, 07, 1);
        revPipe.Name = 'Test Pipeline';
        revPipe.CurrencyIsoCode = 'USD';
    insert revPipe;

    // Get the Revenue Pipeline record with the schedule
    Revenue_Pipeline_Schedule__c revPipeS = [SELECT Id, Amount__c
                                             FROM Revenue_Pipeline_Schedule__c
                                             WHERE Date__c = :date.newInstance(2016, 10, 1)
                                             LIMIT 1];

    // Schedule record should be 1200/12 or 100
    System.assertEquals(100, revPipeS.Amount__c);
}

@isTest static void testCheckRecord() {

    // Create Revenue Pipeline record
    Revenue_Pipeline__c revPipe = new Revenue_Pipeline__c();
        revPipe.Weighted_Product_Price__c = 1200;
        revPipe.Product_Start_Date__c = date.newInstance(2016, 08, 1);
        revPipe.Product_End_Date__c = date.newInstance(2017, 07, 1);
        revPipe.Name = 'Test Pipeline';
        revPipe.CurrencyIsoCode = 'USD';
    insert revPipe;

    // Edit Revenue Pipeline record to change the Price
    Test.startTest();
    revPipe.Weighted_Product_Price__c = 600;
    update revPipe;
    Test.stopTest();

    // Get the Revenue Pipeline record with the schedule
    Revenue_Pipeline_Schedule__c revPipeS = [SELECT Id, Amount__c
                                             FROM Revenue_Pipeline_Schedule__c
                                             WHERE Date__c = :date.newInstance(2016, 10, 1) AND
                                             Revenue_Pipeline__c = :revPipe.Id
                                             LIMIT 1];
    // Schedule record should be 600/12 or 50
    System.debug('Amount is:: ' + revPipeS.Amount__c);
    //System.assertEquals(50, revPipeS.Amount__c);
}

public static void createRevSchedule(Map<Id, Revenue_Pipeline__c> newMap)
{
    List<Revenue_Pipeline_Schedule__c> newSchedule = new List<Revenue_Pipeline_Schedule__c>();
    for(Revenue_Pipeline__c revPipe : newMap.values()) {
        Integer numOfMonths = revPipe.Product_Start_Date__c.monthsBetween(revPipe.Product_End_Date__c) + 1;
        Integer n = revPipe.Subscription_Type__c == 'Subscription' ? 1 : 0;
        for(Integer i=0; i < numOfMonths; i++) {
                Revenue_Pipeline_Schedule__c revSchedule = new Revenue_Pipeline_Schedule__c();
                revSchedule.Amount__c = revPipe.Weighted_Product_Price__c/numOfMonths;
                revSchedule.Date__c = revPipe.Product_Start_Date__c.addMonths(i + n);
                revSchedule.Name = revPipe.Name + ' - ' + revSchedule.Date__c.year() + '-' + revSchedule.Date__c.month();
                revSchedule.Revenue_Pipeline__c = revPipe.Id;
                revSchedule.CurrencyIsoCode = revPipe.CurrencyIsoCode;
                newSchedule.add(revSchedule);
        }
    }
    if(newSchedule.size() > 0){
        try{
            insert newSchedule;
        } catch (DmlException ex) {
            ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.INFO, ex.getMessage()));
        }
    }
}

// Checks if the fields were changed in the newMap compared to OldMap
public void checkUpdate(Map<Id, Revenue_Pipeline__c> newMap, Map<Id, Revenue_Pipeline__c> oldMap)
{
    Map<Id, Revenue_Pipeline__c> revPipeline = new Map<Id, Revenue_Pipeline__c>();

    // Check if the fields changed
    for(Revenue_Pipeline__c revPipe : newMap.values())
    {
        if(
            revPipe.Product_Start_Date__c       != oldMap.get(revPipe.Id).Product_Start_Date__c ||
            revPipe.Product_End_Date__c         != oldMap.get(revPipe.Id).Product_End_Date__c ||
            revPipe.Product_Price__c            != oldMap.get(revPipe.Id).Product_Price__c ||
            revPipe.Weighted_Product_Price__c   != oldMap.get(revPipe.Id).Weighted_Product_Price__c)
            {
                revPipeline.put(revPipe.Id, revPipe);
            }
    }
    if(revPipeline.size() > 0)
    {
        deleteSchedule(revPipeline);
    }
}

// Delete Revenue_Pipeline_Schedule records
public void deleteSchedule(Map<Id, Revenue_Pipeline__c> revPipeline)
{
    List<Revenue_Pipeline_Schedule__c> scheduleToDelete = [SELECT Id,
                                                                 Revenue_Pipeline__r.Id
                                                         FROM Revenue_Pipeline_Schedule__c
                                                         WHERE Revenue_Pipeline__r.Id In :revPipeline.keyset()];
    try{
        delete scheduleToDelete;
    }
    catch (DmlException ex){
        ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.INFO, ex.getMessage()));
    }
    createRevSchedule(revPipeline);
}