Fix timeout in feature test for Mathematica

[slel]

Doctesting src/sage/features/interfaces.py
fails for me with a timeout.

sage: from sage.features.interfaces import Mathematica
sage: Mathematica().is_present()

In this ticket we mark the example
# not tested to skip it in doctests.

CC: @slel

Component: doctest framework

Keywords: features, mathematica, timeout

Author: Samuel Lelièvre

Branch/Commit: 868109b

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/33248

[slel]

comment:1

Set milestone to sage-9.6 after Sage 9.5 release.

[slel]

comment:2

Could we give up on Mathematica().is_present()
after say a minute?

Maybe using one of the answers to:

• Stack Overflow question 492519: Timeout on a function call

[seblabbe]

comment:3

Do you know at which line it gets stuck in what is below ?

    def _is_present(self):
        """
        TESTS::

            sage: from sage.features.interfaces import InterfaceFeature
            sage: from sage.interfaces.sage0 import Sage
            sage: f = InterfaceFeature("sage0", "sage.interfaces.sage0")
            sage: f.is_present()
            FeatureTestResult('sage0', True)
        """
        result = self.module.is_present()
        if not result:
            return result
        m = importlib.import_module(self.module.name)
        try:
            interface = getattr(m, self.name)
        except Exception as exception:
            return FeatureTestResult(self, False,
                                     reason=f"Interface {self.name} cannot be imported: {exception}")
        try:
            interface('2+3')
            return FeatureTestResult(self, True)
        except Exception as exception:
            return FeatureTestResult(self, False,
                                     reason=f"Interface {interface} is not functional: {exception}")

[mkoeppe]

comment:4

I think this doctest should be marked # not tested

[slel]

comment:5

Mathematica is installed on that machine
but requires a password or token to start.

Running math in a shell session goes:

$ math
Mathematica 12.1.1 Kernel for Linux x86 (64-bit)
Copyright 1988-2020 Wolfram Research, Inc.

Mathematica 12.1.1 Kernel cannot find a valid password.

For automatic Web Activation enter your activation key
(enter return to skip Web Activation):

This is likely what makes the feature detection hang.

[slel]

comment:6

Replying to @mkoeppe:

I think this doctest should be marked # not tested

Here is a branch doing that.

---

New commits:

868109b

33248: Skip Mathematica feature detection doctest

[slel]

Changed keywords from features, mathematica to features, mathematica, timeout

[slel]

Commit: 868109b

[slel]

Branch: u/slelievre/33248

[slel]

Author: Samuel Lelièvre

[mkoeppe]

Reviewer: Matthias Koeppe

[vbraun]

Changed branch from u/slelievre/33248 to 868109b