Shopify
Fix large for-loop collection
When a large Range is given in a for-loop (e.g. 1..100000000000000), it may crash the Ruby process or at least eats a lot of memory and takes a significant amount of time to render the template.
I added the following testcase to template_test.rb:
t = Template.parse("{% for a in (1..100000000000000) %} {% for a in (1..10) %} foo {% endfor %} {% endfor %}")
t.resource_limits.render_score_limit = 50
assert_equal "Liquid error: Memory limits exceeded", t.render
assert t.resource_limits.reached?
The render_score_limit does not help here because it's more of a Ruby performance problem in for.rb, where the collection = collection.to_a if collection.is_a?(Range) happens.
A fix may be to check if the given Range is larger than the given render_score_limit. I'm actually not sure if there may be a better fix (e.g. checking the resource limits somewhere else) but at least it works for the given test case.
BTW: You can checkout this branch to show the behavior for a large given collection without the fix:
https://github.com/stayhero/liquid/tree/large_forloop_failing_test?files=1
