How can I unit test the jinja2 template logic?

I've been looking for a way to unit test a jinja2 template. I already did some research, but the only thing I was able to find was related to how to test the variables passed to the template: how to unittest the template variables passed to jinja2 template from webapp2 request handler

In other words, I would like to test if the logic used within the template is generating an expected output.

I thought I could create a "golden" file so I could compare the files being generated with the golden file, however that would require too many "golden" files due to the number of possibilities.

Any other ideas?

Solution

Why not simply render the template to string in your test, and then check if rendered template is correct?

Something simillar to this:

import jinja2

# assume it is an unittest function
context = {  # your variables to pass to template
    'test_var': 'test_value'
}
path = 'path/to/template/dir'
filename = 'template_to_test.tpl'

rendered = jinja2.Environment(
    loader=jinja2.FileSystemLoader(path)
).get_template(filename).render(context)

# `rendered` is now a string with rendered template
# do some asserts on `rendered` string 
# i.e.
assert 'test_value' in rendered

I am not sure how to calculate coverage though.