As a business development professional, it would be concerning to find out that one of your customers was testing out a competitor's product. There are a few potential steps that could be taken in this situation. First, you could try to get in touch with the customer and find out why they are testing out the competitor's product. It could be that there is something that the competitor's product offers that yours does not, and if that is the case, you could try to see if there is anything that can be done to address the issue. If the customer is not forthcoming with information or is unwilling to switch back to your product, you could also reach out to the competitor and try to find out what they are doing differently that has caused your customer to defect. By taking these steps, you can hopefully either win back the customer or learn from the situation and make changes so that it does not happen again in the future.