Instrument usage of bug with iteration of String with offset or 0 limit

[dylanahsmith]

Problem

Looks like 01dea94 introduced a bugs from trying to preserve ruby 1.8.7 behaviour. One that I think seems worth trying to fix is the special case of the limit and offset not applying to a String, which seems like enough of an edge case that it may not be used in practice.

The other regression from that commit demonstrates how little usage there was of String iteration at the time, since in ruby 1.8.7 liquid/ruby would iterate over lines of a String (i.e. String#each would split on the default separator $/).

Solution

Use Liquid::Usage.instrument to see if any code iterates of a String with a positive offset or 0 limit. That way we can decide whether we can fix this buggy behaviour or need to preserve it for backwards compatibility.

[dylanahsmith]

The instrumentation shows there are a couple hundred uses of per-hour, so it looks like existing code already depends on this bug.

Unfortunately, it is hard to dig into the usage (with Liquid::Usage.instrument) to get a concrete example and see if the scope of the bug can be reduced (E.g. Is it the from / to parameter that needs to trigger the bug? Is the bug needed for both the for and tablerow tags? How many themes actually depend on this bug?). Perhaps we should have a different Liquid::Usage method that takes more arguments to we can more easily extract the concrete usage.