Tests

Beside filters, there are also so-called “tests” available. Tests can be usedto test a variable against a common expression. To test a variable orexpression, you add is plus the name of the test after the variable. Forexample, to find out if a variable is defined, you can do name is defined,which will then return true or false depending on whether name is definedin the current template context.

Tests can accept arguments, too. If the test only takes one argument, you canleave out the parentheses. For example, the following twoexpressions do the same thing:

{% if loop.index is divisibleby 3 %}
{% if loop.index is divisibleby(3) %}

The List of Builtin Tests below describes all the builtin tests.