yaml.safe_load broke in CI

[ischoegl]

Problem description

After throwing DeprecationWarnings for a while, yaml.safe_load finally broke.

Steps to reproduce

Run GitHub Actions on a PR.

Behavior

The old deprecation warning was:

build/python/cantera/test/test_composite.py::TestSolutionSerialization::test_yaml_outunits
  /home/runner/work/cantera/cantera/build/python/cantera/test/test_composite.py:579: PendingDeprecationWarning: 
  safe_load will be removed, use
  
    yaml=YAML(typ='safe', pure=True)
    yaml.load(...)
  
  instead
    generated = yaml.safe_load(infile)

The error now is:

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <ruamel.yaml.loader.SafeLoader object at 0x7f536a988208>, block = True
indentless_sequence = True

    def parse_node(self, block=False, indentless_sequence=False):
        # type: (bool, bool) -> Any
        if self.scanner.check_token(AliasToken):
            token = self.scanner.get_token()
            event = AliasEvent(token.value, token.start_mark, token.end_mark)  # type: Any
            self.state = self.states.pop()
            return event
    
        anchor = None
        tag = None
        start_mark = end_mark = tag_mark = None
        if self.scanner.check_token(AnchorToken):
            token = self.scanner.get_token()
            self.move_token_comment(token)
            start_mark = token.start_mark
            end_mark = token.end_mark
            anchor = token.value
            if self.scanner.check_token(TagToken):
                token = self.scanner.get_token()
                tag_mark = token.start_mark
                end_mark = token.end_mark
                tag = token.value
        elif self.scanner.check_token(TagToken):
            token = self.scanner.get_token()
            start_mark = tag_mark = token.start_mark
            end_mark = token.end_mark
            tag = token.value
            if self.scanner.check_token(AnchorToken):
                token = self.scanner.get_token()
                start_mark = tag_mark = token.start_mark
                end_mark = token.end_mark
                anchor = token.value
        if tag is not None:
            handle, suffix = tag
            if handle is not None:
                if handle not in self.tag_handles:
                    raise ParserError(
                        'while parsing a node',
                        start_mark,
                        _F('found undefined tag handle {handle!r}', handle=handle),
                        tag_mark,
                    )
                tag = self.transform_tag(handle, suffix)
            else:
                tag = suffix
        # if tag == '!':
        #     raise ParserError("while parsing a node", start_mark,
        #             "found non-specific tag '!'", tag_mark,
        #      "Please check 'http://pyyaml.org/wiki/YAMLNonSpecificTag'
        #     and share your opinion.")
        if start_mark is None:
            start_mark = end_mark = self.scanner.peek_token().start_mark
        event = None
        implicit = tag is None or tag == '!'
        if indentless_sequence and self.scanner.check_token(BlockEntryToken):
            comment = None
            pt = self.scanner.peek_token()
>           if self.loader and self.loader.comment_handling is None:
E           AttributeError: 'SafeLoader' object has no attribute 'comment_handling'

/opt/hostedtoolcache/Python/3.6.13/x64/lib/python3.6/site-packages/ruamel/yaml/parser.py:414: AttributeError
___________ ERROR at setup of TestModels.test_restore_thermo_models ____________

cls = <class 'cantera.test.test_composite.TestModels'>

    @classmethod
    def setUpClass(cls):
        utilities.CanteraTest.setUpClass()
        cls.yml_file = pjoin(cls.test_data_dir, "thermo-models.yaml")
        with open(cls.yml_file, 'rt', encoding="utf-8") as stream:
>           cls.yml = yaml.safe_load(stream)

../../build/python/cantera/test/test_composite.py:27: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/opt/hostedtoolcache/Python/3.6.13/x64/lib/python3.6/site-packages/ruamel/yaml/main.py:1118: in safe_load
    return load(stream, SafeLoader, version)
/opt/hostedtoolcache/Python/3.6.13/x64/lib/python3.6/site-packages/ruamel/yaml/main.py:1071: in load
    return loader._constructor.get_single_data()

System information

• Cantera version: main
• OS: GH Actions

Affected Tests

*****************************
***    Testing Summary    ***
scons: building terminated because of errors.
*****************************

Tests passed: 1439
Up-to-date tests skipped: 0
Tests failed: 3
Failed tests:
    - python: test_composite.TestSolutionSerialization.test_yaml_outunits
    - python: test_convert.ck2yamlTest.test_extra
    - python: test_convert.ck2yamlTest.test_sri_zero
*****************************

[ischoegl]

The breaking upstream change was apparently reverted, which however still leaves safe_load deprecated and in need of a replacement.