nunjucks shortcodes with no parameter passes empty string to function

[btrem]

Operating system

Ubuntu 20

Eleventy

3.0.0

Describe the bug

If you add a shortcode with no parameter to a nunjucks template, it appears that the engine adds an empty string as a parameter. In other words, {% test %}is equivalent to {% test "" %}. This is not the behavior of liquid templates, where -- it appears -- {% test %}is equivalent to {% test undefined %}.

This might be related to #372. Hard to tell, because there's not much info in the issue, but I looked at the commit that resolved it (5cd19f6), and it looks like the engine adds an empty string (cf. line 80+), apparently to resolve a nunjucks bug.

Reproduction steps

1. Create a shortcode in an eleventy config file.
2. Call that shortcode from a nunjucks template with no parameter.
3. console.log the typeof the parameter.

Expected behavior

In javascript, calling a function with no parameter passes undefined. So I think liquid's behavior is correct, and nunjucks' is not. However, maybe the nunjucks bug #372 prevents consistent behavior.

Demo

https://github.com/btrem/11ty_3788

[zachleat]

Yeah, I can confirm this was added to fix #372, which was a workaround for mozilla/nunjucks#158

I think you’re right that we can fix both #372 and have a predictable undefined but it’ll be a breaking change.

[zachleat]

I pushed this fix to a 3788 branch and am milestoning this and that PR to v4