how can we test HIVE functions without referencing a table

Question

I wanted to understand the UDF WeekOfYear and how it starts the first week. I had to artifically hit a table and run the query . I wanted to not hit the table and compute the values. Secondly can I look at the UDF source code?

SELECT weekofyear
('12-31-2013')
from a;

Answer 1

You do not need table to test UDF since Hive 0.13.0.

See this Jira: HIVE-178 SELECT without FROM should assume a one-row table with no columns

Test:

hive> SELECT weekofyear('2013-12-31');

Result:

1

The source code (master branch) is here: UDFWeekOfYear.java

Answer 2

If you are Java developer, you can write Junit Test cases and test the UDFs..

you can search the source code of all hive built in functions in grepcode.

http://grepcode.com/file/repo1.maven.org/maven2/org.apache.hive/hive-exec/1.0.0/org/apache/hadoop/hive/ql/udf/UDFWeekOfYear.java