Cosmetic Reliablity Test
cosmetic test such as scratch/abrasion test for screen or product covers are used to ensure the product can withstand normal wears appropriately.
It's with a wear eraser that goes back and forth. This test is subjective to each company so it's hard to define a spec here. An recommendation would be performing a competitive analysis with similar product on the market.
Here's a linear abraser test video from Taber (a company that makes the test equipment)
Chemical Sensitivity Test
This is test for delamination, discoloration, and swelling for product enclosure.
Various chemicals are used with Q-tips
common ones are hand sanitizer, dish detergent, glass cleaner, alcohol, etc.
Summary and Conclusion
Abrasion tests the finished product surface's (either flat or contoured) resistance to scratches and common wear and tear.
Chemical sensitivity tests the surface resistance to common household chemicals.
These tests are essential for product to have a longer lasting premium looks.