Add xforms version

[MartijnR]

closes #393

[MartijnR]

@lognaturel, there is one pesky test that outputs odk:xforms-version="" instead of odk:xforms-version="1.0.0". Do you perhaps have an idea to could put me in the right direction to fix this?

[lognaturel]

Taking a look now! Those XForm2json tests are really frustrating. Do you know of anyone using that code to attempt to parse XForms to get JSON?

Also, it looks like this branch as pushed fails several tests. I had to rebase on master to get to the single failure you're describing.

[lognaturel]

At a high-level, I imagine that xform2json.py needs to explicitly save the value of that attribute when it parses an XForm. You probably figured that. Digging deeper...

Edit: ah, except that there's nowhere to save that value in the XLSForm. So no, that's not it. It's the json representation that needs to have that attribute set, maybe?

The XForms version is being treated as a setting and needs to be moved from a model attribute to a setting in the json representation built from XML.

[lognaturel]

lognaturel@f392273 is a fix.

This PR introduces a xforms_version setting. See this form for a sample form that sets the version to 7000. This is a bit strange because it's just passed through with no modification to the output. That is, it's likely to be a lie. On the other hand, depending on the nature of changes to future ODK XForms versions, a user could possibly indicate the intended way of interpreting a form they author? Do we really want to expose this?

[MartijnR]

Thank you so much!

Sorry, I messed up the branch. Indeed, it shouldn't be an XLSForm setting!

[codecov-io]

Codecov Report

Merging #430 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #430      +/-   ##
==========================================
+ Coverage   82.72%   82.73%   +0.01%     
==========================================
  Files          23       23              
  Lines        3386     3389       +3     
  Branches      786      786              
==========================================
+ Hits         2801     2804       +3     
  Misses        439      439              
  Partials      146      146

Impacted Files	Coverage Δ
pyxform/constants.py	100% <100%> (ø)	⬆️
pyxform/survey.py	91.4% <100%> (+0.03%)	⬆️

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[lognaturel]

We took a meandering path to get there but this now looks really great to me! Thanks for bearing with my thinking through the alternatives, @MartijnR. I think we've ended up with a reasonable solution.

[MartijnR]

Thank you! Turned out to be just a simple change, but it got me to explore the exciting world of pyxform. Ready for my next assignment! (No, I'm joking, I need a lengthy rest first!)

[lognaturel]

I need a lengthy rest first!

pyxform makes me feel like that a lot, too. It's definitely a heavy thing maintaining old code bases when the original masterminds aren't around. But everything we do here adds a lot of value to users so that keeps me going.