implement is_functional for LattE executable

[videlec]

Implement the method is_functional for the two LattE features count and integrate so that at least the problem from #38651 raises a meaningful error.

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[antonio-rojas]

Looks like this is not enough to fix the issue, the count and integrate functions in sage/interfaces/latte.py need to explicitly test for Latte_count().is_present() and return an error if false.

[videlec]

Even better with Feature.require(). We now got

sage: P.integral_points_count()
Traceback (most recent call last):
...
FeatureNotPresentError: count is not available.
Call `count` failed with exit code 2
To install count using the arch package manager, you can try to run:
!sudo pacman -Sy 
  !sudo pacman -S latte-integrale
To install count using the Sage package manager, you can try to run:
  !sage -i latte_int
No equivalent system packages for pip are known to Sage.
Further installation instructions might be available at https://www.math.ucdavis.edu/~latte/software.php.

[antonio-rojas]

Even better with Feature.require(). We now got

sage: P.integral_points_count()
Traceback (most recent call last):
...
FeatureNotPresentError: count is not available.
Call `count` failed with exit code 2
To install count using the arch package manager, you can try to run:
!sudo pacman -Sy 
  !sudo pacman -S latte-integrale
To install count using the Sage package manager, you can try to run:
  !sage -i latte_int
No equivalent system packages for pip are known to Sage.
Further installation instructions might be available at https://www.math.ucdavis.edu/~latte/software.php.

Nice, but the pacman part will only work if you're running sage from the distro (which is patched to use the modified executable names)

[antonio-rojas]

The is_functional test doesn't work. The count command returns exit code 1, so CalledProcessError is always raised. Even count --help returns 1.

[videlec]

The is_functional test doesn't work. The count command returns exit code 1, so CalledProcessError is always raised. Even count --help returns 1.

That is very unfortunate...