Corner Cases and Product Safety Nets
Techniques for product managers to handle non-standard use cases
"That's just a corner case!"
What is a good response when you hear this in a requirements review? Product managers often hear this about abnormal situations outside of regular product operations.
This article provides constructive ways to handle corner cases while minimizing the risk to the product if a customer hits a corner case.
Understanding Corner Cases
Don't debate a corner case with your product team until you have a chance to evaluate the risk to customers.
Likewise, don't neglect corner cases. That little worry you feel about a corner case could be a valid and overlooked issue in your product.
Often a corner case is a double failure that no one anticipated.
The key items to evaluate on a corner case are:
The frequency of occurrence
How likely are the conditions leading to the corner case happening?
The impact of the occurrence
Is there a business, brand, or service impact?
The likelihood of hitting the corner case with an impact
What is the risk of something bad happening?
The top corner cases for product managers to handle:
A security breach
A performance issue
A poor user experience
As a product manager, your efforts to prevent issues in security, performance, and user experience are likely to be met with "This is a corner case". Meaning: that the issue is not worth handling.
Let's dig into getting the right attention on the top corner cases for product managers to handle.
Strategies to Prevent Product Security Issues
A security breach is going to make its way to product managers. It is best to head off security concerns with prevention and baseline product security.
If you don't already know your product security baseline, then find it. If there is no security baseline, then put priority on basic product security:
Regular vulnerability testing of the product
Static code scanning
Incident handling process
Documentation on security
Cross-functional security team
Additionally, your organization's security training is a great starting point.
However, don't let a corner case hold you back from evaluating the risk and customer impact of a security breach. Use your security baseline to estimate the risk of a security corner case.
A product security failure can impact your product and your organization. Listen to your inner voice and protect against security breaches.
Ensuring Scalability and Performance
Customer satisfaction can plummet before product managers hear about a performance issue or a concern about product capacity. These types of product issues can hurt the trust that customers put in your product.
To evaluate a performance or scale corner case, check what kind of load testing and stress testing is done on your product. Understand to what scale your product is tested and the type of performance testing that is executed.
Then evaluate the risk of the performance/scale corner case. Depending on the risk, it might be enough to add scale limits to your product documentation instead of building to a scale that is unlikely to be needed.
Another safety net to consider is monitoring your customers' deployment scale to be sure the customers are staying within the limits of your performance and scale testing.
User Experience Cases
Avoid confusion in your users when they are using your product. A poor user experience that confuses customers generates extra support calls.
When evaluating a corner case that affects the user experience, you can use feature flags and customer documentation to offset corner case impacts on a new feature.
For existing features with a corner case, the risk of confusion is higher. Customers are used to a certain experience. You need to be thorough in corner case evaluation when a high-usage feature is changed.
You can also monitor for customer experience issues with your support team for early detection of customers becoming frustrated with the user experience.
Techniques to Handle a Corner Case
When you find a corner case that affects security, product performance, or user experience, then do the risk assessment.
Document your findings and confirm with your product team. Then take these steps depending on the risk:
If the risk of the corner case is minor, then no further action is needed.
If the risk of the corner case is major, then take protective steps to prevent damage from the corner case.
If the risk of the corner case is critical and there is no protection in the product, then calculate the business risk and escalate in your organization.
Your role in handling the corner case is to ensure that affected teams understand the risk.
Conclusion - Prevent Future Product Issues
Debating corner cases with your product team is pointless. Product delivery teams that overly focus on corner cases can't deliver game-changing products.
Product managers are in the best position to evaluate the risk of a corner case and take proactive steps to prevent critical product issues.
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Great write up. Corner cases are pretty interesting, when I was at Apple we had the reverse come true where we built some hardware features to address corner cases, resulting in a negative experience for the majority of users.
Very informative. Thanks!