Assert in Pig 0.12.0 doesn't work. Pig 0.12.1/0.13.0 fixed this issue.
This patch is listed as having been included in CDH 5.0. However, in CDH 5.2 (haven't tested others), Assert does not work. I have verified that 0.12.1 Apache Pig is fixed and assert works. This is a CDH problem.
To reproduce, simply use assert in a Pig shell. It doesn't get past grunt:
ASSERT my_relation by foo IS NOT NULL, 'Foo is null';
Thank you for the bug report Russell. I can confirm that the ASSERT from grunt shell doesn't seem to be working for me either. Could you open a bug report on DISTRO JIRA?