Test
Trivial Description
Currently, there are some tests testing function descriptions:
$ grep -ir "describe function" sql/core/src/test/resources/sql-tests/inputs
sql/core/src/test/resources/sql-tests/inputs/json-functions.sql:describe function to_json;
sql/core/src/test/resources/sql-tests/inputs/json-functions.sql:describe function extended to_json;
sql/core/src/test/resources/sql-tests/inputs/json-functions.sql:describe function from_json;
sql/core/src/test/resources/sql-tests/inputs/json-functions.sql:describe function extended from_json;
Looks there are not quite good points about testing them since we're not going to test documentation itself.
For DESCRIBE FCUNTION functionaility itself, they are already being tested here and there.
See the test failures in https://github.com/apache/spark/pull/18749 (where I added examples to function descriptions)
We better remove those tests so that people don't add such tests in the SQL tests.
