This is really something where you would use a Filter to target laptops, perhaps by creating a filter based on Chassis Package Type = 9 (laptop) or 10 (notebook), or by creating a filter that only returns computers whose model contains 'Latitude' in the model name, for example. Applicability rules have to do with operating systems and applications, not hardware. If you want to restrict based on hardware, you'll need to use a filter.
Applicability rules and detection rules are tested in very similar manners. Apply them to test systems, I typically use a Managed Software Delivery that checks for compliance every 15 minutes, and then tweak settings to try to break the logic of the software resource within the MSD. For example, uninstall pre-requisites, corrupt the primary program, target a 64-bit system even though your MSD contains a software resource that is applicable to 32-bit OS's only, and so forth.
For example, I once created a detection rule that .NET 2.0 needed to have a version containing the substring 2. in the registry, but determined in testing that a registry value of, say, 3.042.67 would have validated as having .NET 2.0. I changed the detection rule to include a version greater than or equal to 2.0 and less than or equal to 3.0.