Unfriendly error when the version can't be determined

[Roman Donchenko]

Given this setup:

$ ls
changes  towncrier.toml
$ cat towncrier.toml
[tool.towncrier]
directory = "changes"

running towncrier build yields this error message:

Loading template...
Finding news fragments...
Rendering news fragments...
Traceback (most recent call last):
  File "/home/dpb/.local/bin/towncrier", line 8, in <module>
    sys.exit(cli())
  File "/home/dpb/.local/pipx/venvs/towncrier/lib/python3.10/site-packages/click/core.py", line 1130, in __call__
    return self.main(*args, **kwargs)
  File "/home/dpb/.local/pipx/venvs/towncrier/lib/python3.10/site-packages/click/core.py", line 1055, in main
    rv = self.invoke(ctx)
  File "/home/dpb/.local/pipx/venvs/towncrier/lib/python3.10/site-packages/click/core.py", line 1657, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/dpb/.local/pipx/venvs/towncrier/lib/python3.10/site-packages/click/core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/dpb/.local/pipx/venvs/towncrier/lib/python3.10/site-packages/click/core.py", line 760, in invoke
    return __callback(*args, **kwargs)
  File "/home/dpb/.local/pipx/venvs/towncrier/lib/python3.10/site-packages/towncrier/build.py", line 89, in _main
    return __main(
  File "/home/dpb/.local/pipx/venvs/towncrier/lib/python3.10/site-packages/towncrier/build.py", line 147, in __main
    project_version = get_version(
  File "/home/dpb/.local/pipx/venvs/towncrier/lib/python3.10/site-packages/towncrier/_project.py", line 40, in get_version
    module = _get_package(package_dir, package)
  File "/home/dpb/.local/pipx/venvs/towncrier/lib/python3.10/site-packages/towncrier/_project.py", line 19, in _get_package
    module = import_module(package)
  File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1047, in _gcd_import
  File "<frozen importlib._bootstrap>", line 981, in _sanity_check
ValueError: Empty module name

This in no way describes the actual problem, which is that towncrier couldn't determine the project version. It would be nice if it could display a friendlier message, e.g. "Unable to determine the project version. Use the --version option."

[Adi Roiban]

Thanks for the report.

The final error is "ValueError: Empty module name"

It looks like the problem is not the version.

To me it looks like, towncrier has no idea for which project/source it's supposed to work on.

Towncrier is designed to be used by software developers.
So the error show a full traceback in an attempt to be developer friendly and not end-user friendly :)

Have you reviewed the docs from https://towncrier.readthedocs.io/en/stable/quickstart.html ?

From your cat, I don't see the package and package_dir configurations.

The most basic configuration is annotated below:


[tool.towncrier]
    # The name of your Python package
    package = "myproject"
    # The path to your Python package.
    # If your package lives in 'src/myproject/', it must be 'src',
    # but if you don't keep your code in a 'src' dir, remove the
    # config option
    package_dir = "src"
    # Where you want your news files to come out. This can be .rst
    # or .md, towncrier's default template works with both.
    filename = "NEWS.rst"

[Roman Donchenko]

My config file is actually the first example from here: https://towncrier.readthedocs.io/en/stable/index.html#quick-start.

In this example (and the project I'm considering to use towncrier in) there is no Python project, and you're supposed to supply the version number manually.

[Adi Roiban]

True. Thanks for the details

So the issue is something like this.

If no version is found, towncrier fallbacks to detect the version via python auto-detections, but if Python project is not defined/found, it ends up with the ValueError: Empty module name error.

---

Not sure how to fix it

I guess that in towncrier/build.py when get_version is called, it needs to be enclosed in a try/catch and show a better error message

I am leaving this report open and happy to review a fix for it :)

Thanks again for the report

[Adi Roiban]

Another option to fix this, is throwing more documentation into trying to fix this, and highlight that for non-python project, a version is required.

There is room for improvements, we just need time for this :)

[Roman Donchenko]

I guess that in towncrier/build.py when get_version is called, it needs to be enclosed in a try/catch and show a better error message

It could just display the error message if config.package is blank at that point.