If you are not a vendor/manufacturer of the IC in question, testing ViH/ViL is nearly impossible unless its complexity is low as an inverter or other simple logic gate.
If you are a vendor/designer of the IC, the IC must have built-in means for testability of these parameters. It is called DFT, "Design For Test". It is the vendor job to characterize their IC to meet the advertised ViH/ViL specifications.
Essentially the DFT features of a IC make it possible to relay the state of every Input pin either into a specially dedicated common output (just like a simple inverter does), or there are dedicated built-in test registers that are accessible via debug chains as JTAG that latch the outcome of GPIO state. These tools are usually not disclosed to public, so a customer can't use them.
To ensure compliance with their own specifications, a manufacturer will run these tests under different chip temperatures, supply voltages, and over various grades of silicon material, which are called "corners" [of validation space]. This is usually done on a very expensive Automatic Test Equipment (ATE machines that cost millions of US$) using "load boards" specifically designed for each particular IC. A massive statistics is gathered and guardbands are added to ensure that the parameter never fails the stated levels.
As result, there is not much sense for a user to re-validate all this massive work, unless you have some problem with signals not getting through. In this case it is the best to get into contact with the vendor of IC for fastest resolution of the issue.