The objectives of the third test, the Solution Test, are to refine your product to an exact match with customer needs. At this stage, the validation of your product is paid pilots as well as validation on the price point and breakthrough questions. This test is simple but challenging. In the Solution Test, you seek to partner with your customers to develop a solution, usually through a pilot program, to take your solution through a final round of iteration to refine it into the solution customers want. On the one hand, the test is simple because it resembles the second test (the Prototype Test), but with an actual product that becomes marketable and salable. On the other hand, the test is challenging because at this point if you have correctly validated the pain and the solution hypotheses, then your customers should be willing to begin paying for the product. It is where the rubber meets the road, and you should begin closing paid pilots or selling your product.
In the traditional product development model, new ventures don’t face this kind of pressure. Instead, the product is still in what is often called “beta” stage, and most of the time engineers are quietly pounding away on the product without showing it to anyone. If the product is being shown to customers at all, it is often to assess problems with the technology or marketing strategy, not with whether the product actually solves the pain. By the end of this phase ("Nailing the Solution") and the next phase ("Nailing the Go-to-Market Strategy," which actually runs parallel with this phase), you should have nailed your product solution and be ready to start selling your product.
(See Nail It Then Scale It, pgs. 130-131)