Improve fail message when library doesn't exist

[lukaszachy]

When /foo doesn't exist in the fmf root tmt should provide better error than saying AttributeError: 'NoneType' object has no attribute 'data'

Pull Request Checklist

• implement the feature
• extend the test coverage

[lukaszachy]

Previous TB was

/var/tmp/tmt/run-287

/default/plan
    discover
        how: fmf
        directory: /tmp/r_171158_diE

plan failed

    Traceback (most recent call last):
      File "/usr/lib/python3.12/site-packages/tmt/__main__.py", line 18, in run_cli
        tmt.cli.main()
      File "/usr/lib/python3.12/site-packages/click/core.py", line 1130, in __call__
        return self.main(*args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/usr/lib/python3.12/site-packages/click/core.py", line 1055, in main
        rv = self.invoke(ctx)
             ^^^^^^^^^^^^^^^^
      File "/usr/lib/python3.12/site-packages/click/core.py", line 1657, in invoke
        return _process_result(sub_ctx.command.invoke(sub_ctx))
                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/usr/lib/python3.12/site-packages/click/core.py", line 1689, in invoke
        return _process_result(rv)
               ^^^^^^^^^^^^^^^^^^^
      File "/usr/lib/python3.12/site-packages/click/core.py", line 1626, in _process_result
        value = ctx.invoke(self._result_callback, value, **ctx.params)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/usr/lib/python3.12/site-packages/click/core.py", line 760, in invoke
        return __callback(*args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/usr/lib/python3.12/site-packages/click/decorators.py", line 26, in new_func
        return f(get_current_context(), *args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/usr/lib/python3.12/site-packages/tmt/cli.py", line 508, in finito
        click_context.obj.run.go()
      File "/usr/lib/python3.12/site-packages/tmt/base.py", line 3560, in go
        raise tmt.utils.GeneralError(
    tmt.utils.GeneralError: plan failed

The exception was caused by 1 earlier exceptions

Cause number 1:

    'NoneType' object has no attribute 'data'

        Traceback (most recent call last):
          File "/usr/lib/python3.12/site-packages/tmt/base.py", line 3556, in go
            plan.go()
          File "/usr/lib/python3.12/site-packages/tmt/base.py", line 2289, in go
            step.go()
          File "/usr/lib/python3.12/site-packages/tmt/steps/discover/__init__.py", line 345, in go
            phase.go()
          File "/usr/lib/python3.12/site-packages/tmt/steps/discover/fmf.py", line 475, in go
            self.do_the_discovery(path)
          File "/usr/lib/python3.12/site-packages/tmt/steps/discover/fmf.py", line 619, in do_the_discovery
            test.require, test.recommend, _ = tmt.libraries.dependencies(
                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^
          File "/usr/lib/python3.12/site-packages/tmt/libraries/__init__.py", line 158, in dependencies
            library = library_factory(
                      ^^^^^^^^^^^^^^^^
          File "/usr/lib/python3.12/site-packages/tmt/libraries/__init__.py", line 109, in library_factory
            library.fetch()
          File "/usr/lib/python3.12/site-packages/tmt/libraries/beakerlib.py", line 326, in fetch
            self._merge_metadata(library_path, local_library_path)
          File "/usr/lib/python3.12/site-packages/tmt/libraries/beakerlib.py", line 202, in _merge_metadata
            data=tmt.utils.get_full_metadata(library_path, self.name),
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
          File "/usr/lib/python3.12/site-packages/tmt/utils.py", line 2581, in get_full_metadata
            return fmf.Tree(fmf_tree_path).find(node_path).data
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        AttributeError: 'NoneType' object has no attribute 'data'

[lukaszachy]

How it will be

/var/tmp/tmt/run-296

/default/plan
    discover
        how: fmf
        directory: /tmp/r_171158_diE

plan failed

The exception was caused by 1 earlier exceptions

Cause number 1:

    Can't find library @ name: /Library/basic, url: https://pkgs.devel.redhat.com/git/tests/vsftpd, ref: master.

    The exception was caused by 1 earlier exceptions

    Cause number 1:

        '/Library/basic' not found in the '/var/tmp/tmt/run-296/default/plan/discover/default-0/tmpl12iouq2/pkgs.devel.redhat.com/vsftpd/Library/basic' Tree.

[LecrisUT]

In the testing suite is it possible to catch-all any traceback? It would be nice to make sure all expected failures produce a useful message, while a traceback would mean tmt did not expect that to happen.

[thrix]

Would it be possible to add some tests for this?

[psss]

Would it be possible to add some tests for this?

Yeah, that would be nice. @lukaszachy, any simple way to extend the existing test coverage? I quickly tried to reproduce the problem but I end up with the following error instead:

After beakerlib processing, tests may have only simple requirements

[lukaszachy]

Finally reproduced again: repo with fmf root, directory exists as well but the 'main.fmf' of the library node isn't there.

[lukaszachy]

When adding the test I realized that 'Library @ name' isn't the best way to report the problem.
I've changed it to

plan failed

The exception was caused by 1 earlier exceptions

Cause number 1:

    Library with fmf_id='name: /dir-without-fmf, url: https://github.com/teemtee/tests, ref: missing-node-data, path: /nested' doesn't exist.

    The exception was caused by 1 earlier exceptions

    Cause number 1:

        '/dir-without-fmf' not found in the '/var/tmp/tmt/run-057/plan/certificate/missing/node-metadata/discover/default-0/tmp_5e3wcv3/github.com/tests/nested/dir-without-fmf' Tree.

[lukaszachy]

Once teemtee/tests#7 is merged I can/will have to drop the 'ref' from the test.

[psss]

Looks good, thanks for improving this. Just one typo.

[psss]

Test failure irrelevant --> merging.