RuntimeError: generator raised StopIteration when fixing

[alexmojaki]

1. Clone https://github.com/pydantic/logfire
2. make install
3. pytest --inline-snapshot=fix

Results in:

Traceback (most recent call last):
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/inline_snapshot/_inline_snapshot.py", line 284, in check
    old_value_element, old_node_element = next(old)
                                          ^^^^^^^^^
StopIteration

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/alex/work/logfire/.venv/bin/pytest", line 8, in <module>
    sys.exit(console_main())
             ^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/_pytest/config/__init__.py", line 201, in console_main
    code = main()
           ^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/_pytest/config/__init__.py", line 175, in main
    ret: ExitCode | int = config.hook.pytest_cmdline_main(config=config)
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_hooks.py", line 513, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 139, in _multicall
    raise exception.with_traceback(exception.__traceback__)
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 103, in _multicall
    res = hook_impl.function(*args)
          ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/_pytest/main.py", line 330, in pytest_cmdline_main
    return wrap_session(config, _main)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/_pytest/main.py", line 318, in wrap_session
    config.hook.pytest_sessionfinish(
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_hooks.py", line 513, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 139, in _multicall
    raise exception.with_traceback(exception.__traceback__)
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/_pytest/logging.py", line 868, in pytest_sessionfinish
    return (yield)
            ^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 124, in _multicall
    teardown.send(result)  # type: ignore[union-attr]
    ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/_pytest/terminal.py", line 903, in pytest_sessionfinish
    self.config.hook.pytest_terminal_summary(
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_hooks.py", line 513, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 139, in _multicall
    raise exception.with_traceback(exception.__traceback__)
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/_pytest/terminal.py", line 925, in pytest_terminal_summary
    return (yield)
            ^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/_pytest/warnings.py", line 132, in pytest_terminal_summary
    return (yield)
            ^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/pluggy/_callers.py", line 103, in _multicall
    res = hook_impl.function(*args)
          ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/inline_snapshot/pytest_plugin.py", line 218, in pytest_terminal_summary
    for change in snapshot._changes():
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/inline_snapshot/_inline_snapshot.py", line 753, in _changes
    yield from self._value._get_changes()
  File "/Users/alex/work/logfire/.venv/lib/python3.12/site-packages/inline_snapshot/_inline_snapshot.py", line 398, in _get_changes
    yield from check(self._old_value, self._ast_node, self._new_value)
RuntimeError: generator raised StopIteration

You will also see a test failure caused by #112, that's unrelated, the same error happens when the test is deleted.

No tests need fixing. pytest alone passes fine. If I wrap the offending loop body in inline-snapshot with:

try:
    ...
except StopIteration:
    break

then pytest --inline-snapshot=fix completes fine without making any changes. I'm guessing this happens when generating the Update snapshots report, which BTW I would be quite happy to not see at all.

[15r10nk]

Sorry that this took so long.

Your problem is caused by your *issue_lines in your snapshots.

The following example has also a problem (but a different exception)

from inline_snapshot import snapshot


def test_star():
    values = [1]
    assert [0, 1, 5] == snapshot([0, *values, 5])

Can you work for now without star expressions in snapshots?
I find your tests really cool and star expressions can be really useful with snapshots, but the problem is that they are not supported by the current implementation.

I will check for them and warn the user that snapshots with star-expressions are currently not supported. I hope this is ok for you.

I will also look into your updates and try to figure out why they are so noisy.

[15r10nk]

fixed in 0.13.2