According to the documentation here, tests can be placed into a View file but this seems counter-intuitive to how a test is designed to function.
Tests (unfortunately) require an Explore to work as part of the explore_source parameter. Explores include Views to function. Some Views can even be included in multiple Explores
Adding a test to a View, therefore, creates a weird hybrid context where the View has a reference to a specific, parent Explore. Seems very messy - why would this be an option?