TypeError in assertTemplateUsed when using pathlib.Path as template_name

[Erik Z.]

Right now it is perfectly fine to use pathlib.Path as an template_name. This works fine for production as the template render fine. However when unit testing the assertTemplateUsed function throws a TypeError:

File "<stuff>/.local/lib/python3.12/site-packages/django/test/testcases.py", line 681, in _assert_template_used
        % (template_name, ", ".join(template_names)),
                          ^^^^^^^^^^^^^^^^^^^^^^^^^
    TypeError: sequence item 0: expected str instance, PosixPath found

This happens because the template_name is stored as is.

Happened on 5.0.4

[Natalia Bidart]

Hello Erik! Thank you for your report.

The PR you have submitted is not ideal in that the "production" code is coercing to str in multiple places and this could impact performance.
Following your description, and ideally, we should provide a fix within the Testing framework.

To fully understand this issue, I would need a minimal django project (views and tests) so we can reproduce this, triage it and review the fix accordingly.

[Erik Z.]

Sure, I can understand that.
I prepared a project which should give an understanding on how the error works.
It can be found here: ​https://github.com/guserav/django_bug_test_template_name_str/
all important code should be in ​https://github.com/guserav/django_bug_test_template_name_str/commit/828d56b405c7932fdcf6c6c29a9038ce115628ed

[Rish]

I tried to reproduce this bug using the repo provided: ​https://github.com/guserav/django_bug_test_template_name_str/
Can't seem to reproduce it, all tests run just fine on django version 5.0.4.
Can you please elaborate more on this?

[Erik Z.]

The tests are deliberatly designed to run through. I removed the Exception assertions that made the tests work. Now the tests are failing.