[Python-modules-team] Bug#911873: python-transitions FTBFS: tests fail with Python 3.7: RuntimeError: generator raised StopIteration

[Helmut Grohne]

Source: python-transitions
Version: 0.6.7-1
Severity: serious
Tags: ftbfs

python-transitions fails to build from source. Its test suite has lots
of these:

| ======================================================================
| ERROR: test_use_machine_as_model (tests.test_states.TestStatesDiagramsLockedNested)
| ----------------------------------------------------------------------
| Traceback (most recent call last):
|   File "/<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build/transitions/extensions/diagrams.py", line 376, in _get_graph
|     return self.model_graphs[model] if not show_roi else self._graph_roi(model)
| KeyError: <tests.utils.Stuff object at 0x7fbc63fab048>
| 
| During handling of the above exception, another exception occurred:
| 
| Traceback (most recent call last):
|   File "/usr/lib/python3/dist-packages/pygraphviz/agraph.py", line 1093, in subgraphs_iter
|     raise StopIteration
| StopIteration
| 
| The above exception was the direct cause of the following exception:
| 
| Traceback (most recent call last):
|   File "/<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build/tests/test_states.py", line 169, in setUp
|     super(TestStatesDiagramsLockedNested, self).setUp()
|   File "/<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build/tests/test_graphing.py", line 290, in setUp
|     super(TestDiagramsLockedNested, self).setUp()
|   File "/<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build/tests/test_graphing.py", line 222, in setUp
|     super(TestDiagramsNested, self).setUp()
|   File "/<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build/tests/test_graphing.py", line 89, in setUp
|     self.stuff = Stuff(machine_cls=self.machine_cls)
|   File "/<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build/tests/utils.py", line 20, in __init__
|     self.machine = machine_cls(*args, **kwargs)
|   File "/<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build/transitions/extensions/diagrams.py", line 363, in __init__
|     model.get_graph()
|   File "/<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build/transitions/extensions/diagrams.py", line 378, in _get_graph
|     return self._get_graph(model, title, force_new=True, show_roi=show_roi)
|   File "/<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build/transitions/extensions/diagrams.py", line 373, in _get_graph
|     self.model_graphs[model] = self.graph_cls(self).get_graph(title if title is not None else self.title)
|   File "/<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build/transitions/extensions/diagrams.py", line 179, in get_graph
|     self._add_edges(self.machine.events.copy(), fsm_graph)
|   File "/<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build/transitions/extensions/diagrams.py", line 222, in _add_edges
|     for sub in container.subgraphs_iter():
| RuntimeError: generator raised StopIteration
| 
| ----------------------------------------------------------------------
| Ran 981 tests in 15.914s
| 
| FAILED (errors=323)
| E: pybuild pybuild:338: test: plugin distutils failed with: exit code=1: cd /<<PKGBUILDDIR>>/.pybuild/cpython3_3.7_transitions/build; python3.7 -m nose -v tests
| dh_auto_test: pybuild --test -i python{version} -p "3.7 3.6" returned exit code 13
| make: *** [debian/rules:10: build] Error 25
| dpkg-buildpackage: error: debian/rules build subprocess returned exit status 2

Likely this is due to Python 3.7 having become a supported Python
version and Python 3.7 having changed behaviour wrt. generators.

Helmut