How many columns can generic tests be defined on?

Generic tests in dbt can be defined on as many columns as needed. This flexibility allows users to apply the same testing logic across multiple columns, enhancing the efficiency of data validation processes. For instance, if you have a test that checks for uniqueness or null values, you can apply this to a variety of columns in a model without needing to write separate tests for each column. This capability supports better scalability and maintainability of your testing strategy within the dbt framework, as you can ensure the integrity of multiple data points simultaneously with a single generic test definition.

The other choices highlight more restrictive conditions that do not accurately reflect the capabilities of generic tests in dbt.