You will often work with a partner(s) on lab assignments in CS class. Sometimes your partner will be assigned by your professor. Other times you may choose your own partner.
Partnered work is very important in CS. It teaches you how to effectively work collaboratively with other people; something that mirrors what you will have to do in your post-Swarthmore life.
The expectation is that you and your partner are working together side by side in the lab for most, if not all, of the time you work on a lab assignments. You and your partner should work on all aspects of the project together: initial design, incremental testing and debugging, and final stress testing and code review. There may be short periods of time where you each go off and implement some small part independently. However, you should frequently come back together, talk through your changes, push and pull each others code from your shared repo and try out your merged code together. Taking time to design a plan for your solution together and to doing incremental implementation and testing together may seem like it is a waste of time, but in the long run it will save you a lot of time by making it less likely that you have design or logic errors in your solution, and by having a partner to help track down bugs and to help come up with solutions to problems.
Partnerships where partners work mostly independently rarely work out well and rarely result in complete, correct and robust solutions. Partnerships where partners work side-by-side for all or most of the time tend to work out very well.
You and your partner are both equally responsible for initiating scheduling times when you can meet to work together, and for making time available in your schedule for working together.
You are also both responsible for making sure that you each put in your fair share of work on the project; this means both of you make the effort to work with your partner rather than just doing all the work on your own and not including your partner, and that you both initiate meetings with your partner and that you show up to meetings ready to do your part.
People have different strengths. View your partnered work as both an opportunity to learn something from your partner and an opportunity to help your partner learn something that you do well. We all have something to offer and we all have something to learn.