Salesforce: Is there any way to set System time in test class

So I have a trigger and a schedule class. The trigger will fire upon update on an object and schedule a job which will execute the scheduled class. There is some logic in the trigger related to non-working hours, weekends and holidays. It will usually schedule the job 1 hour after insert (due to business requirement). but if insert happens over the weekend, afterhours, or holidays. It will schedule the next business day 8am.

Opportunity Management

This is my first post here on the StackExchange and hoping someone can help. I have been tasked with finding a way to prevent users from moving to 70% or greater probability in an opportunity when Opportunity Products with a certain record type exist. We have valid SAP products and what we call Prospect Products (these shouldn’t be allowed in opportunity with 70% or greater probability). We are also thinking of adding a field to the product table for prospect products that are “allowed” so those would obviously need to be excluded from the criteria and can be allowed in the forecast.

Governor Limit question: Large data set. How do I avoid hitting governor limits?

We have a pretty complex trigger suite on our org. We’ve built a lot of custom functionality. I’m starting to worry about governor limits and not really understanding how to manage them. I’ve read through http://wiki.developerforce.com/page/Apex_Code_Best_Practices and I’ve made all my triggers accordingly, using as few SOQL and DML statements as possible, querying the database only when I have to and getting all the records I need at once, etc.