test_future_import asserts due to result_lines returning 2.3999999999999999 and not 2.4

[RossComputerGuy]

=================================== FAILURES ===================================
________________________ FuturesTest.test_future_import ________________________
Traceback (most recent call last):
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/runner.py", line 341, in from_call
    result: Optional[TResult] = func()
                                ^^^^^^
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/runner.py", line 241, in <lambda>
    lambda: runtest_hook(item=item, **kwds), when=when, reraise=reraise
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_hooks.py", line 513, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_callers.py", line 139, in _multicall
    raise exception.with_traceback(exception.__traceback__)
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/threadexception.py", line 87, in pytest_runtest_call
    yield from thread_exception_runtest_hook()
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/threadexception.py", line 63, in thread_exception_runtest_hook
    yield
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/unraisableexception.py", line 90, in pytest_runtest_call
    yield from unraisable_exception_runtest_hook()
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/unraisableexception.py", line 65, in unraisable_exception_runtest_hook
    yield
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/logging.py", line 850, in pytest_runtest_call
    yield from self._runtest_for(item, "call")
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/logging.py", line 833, in _runtest_for
    yield
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/capture.py", line 878, in pytest_runtest_call
    return (yield)
            ^^^^^
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_callers.py", line 122, in _multicall
    teardown.throw(exception)  # type: ignore[union-attr]
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/skipping.py", line 257, in pytest_runtest_call
    return (yield)
            ^^^^^
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_callers.py", line 103, in _multicall
    res = hook_impl.function(*args)
          ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/runner.py", line 183, in pytest_runtest_call
    raise e
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/runner.py", line 173, in pytest_runtest_call
    item.runtest()
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/python.py", line 1632, in runtest
    self.ihook.pytest_pyfunc_call(pyfuncitem=self)
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_hooks.py", line 513, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_callers.py", line 139, in _multicall
    raise exception.with_traceback(exception.__traceback__)
  File "/nix/store/130vq5jz29v89na1hj9x2kgkhlj3ysbc-python3.12-pluggy-1.5.0-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/pluggy/_callers.py", line 103, in _multicall
    res = hook_impl.function(*args)
          ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/nix/store/lfj9h46jsidlg7mg4yy33rspmls6a046-python3.12-pytest-8.2.2-aarch64-unknown-linux-gnu/lib/python3.12/site-packages/_pytest/python.py", line 162, in pytest_pyfunc_call
    result = testfunction(**testargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/Mako-1.3.5/test/test_template.py", line 1756, in test_future_import
    assert result_lines(t.render(x=12, y=5)) == ["2.4"]
AssertionError: assert ['2.3999999999999999'] == ['2.4']

  At index 0 diff: '2.3999999999999999' != '2.4'

  Full diff:
    [
  -     '2.4',
  +     '2.3999999999999999',
    ]
=============================== warnings summary ===============================
test/ext/test_babelplugin.py: 32 warnings
  /nix/store/hv4r766mi1ldavss9dg5nagb80cgifs1-python3.12-babel-2.15.0/lib/python3.12/site-packages/babel/messages/extract.py:643: DeprecationWarning: ast.Str is deprecated and will be removed in Python 3.14; use ast.Constant instead
    if isinstance(body, ast.Str):

test/ext/test_babelplugin.py: 31 warnings
  /nix/store/hv4r766mi1ldavss9dg5nagb80cgifs1-python3.12-babel-2.15.0/lib/python3.12/site-packages/babel/messages/extract.py:644: DeprecationWarning: Attribute s is deprecated and will be removed in Python 3.14; use value instead
    return body.s

test/ext/test_linguaplugin.py::MakoExtractTest::test_extract
  /nix/store/4svh14lbp62c25jc3073sgkddh8dr5i9-python3.12-lingua-4.15.0/lib/python3.12/site-packages/lingua/extractors/__init__.py:2: DeprecationWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html
    from pkg_resources import DistributionNotFound

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
=========================== short test summary info ============================
FAILED test/test_template.py::FuturesTest::test_future_import - AssertionError: assert ['2.3999999999999999'] == ['2.4']
=========== 1 failed, 449 passed, 49 skipped, 64 warnings in 18.87s ============
/nix/store/b4jyim3n8vlq4nqcasfhq8kqs3y80wkc-stdenv-linux/setup: line 1641: pop_var_context: head of shell_variables not a function context

Discovered with Nix

[zzzeek]

I cant reproduce , note python 3.12 below

]$ pytest test/test_template.py::FuturesTest::test_future_import 
==================================================================================== test session starts =====================================================================================
platform linux -- Python 3.12.4, pytest-8.1.0, pluggy-1.4.0 -- /home/classic/.venv3/bin/python
cachedir: .pytest_cache
rootdir: /home/classic/dev/mako
configfile: setup.cfg
plugins: xdist-3.4.0, anyio-4.1.0, random-0.2, repeat-0.9.3
collected 1 item                                                                                                                                                                             

test/test_template.py::FuturesTest::test_future_import PASSED                                                                                                                          [100%]

===================================================================================== 1 passed in 0.05s ======================================================================================
[classic@framework mako:review/michael_bayer/update_pyproject]$ 

[RossComputerGuy]

Interesting, are you on aarch64? I'm doing this on NixOS on an aarch64 system (Apple Silicon M1 Pro). I've tried running this test multiple times and it consistently. I also am using an LLVM built environment so I wonder if some sort of optimization could have caused this.

[zzzeek]

OK so this is some kind of CPU thing? im on x86_64. if this is doing a pure FP comparison then the test should be changed to use rounding or something, feel free to send a PR.

[RossComputerGuy]

Possibly, I am not 100% sure. I'm going to try an x86_64 machine as well.