doctest failing in designs/incidence_structures.py

[seblabbe]

With Ubuntu 18.04 + 9.2.beta13, running

sage -t src/sage/combinat/designs/incidence_structures.py

and

Using
--optional=4ti2,build,ccache,cryptominisat,dochtml,dot2tex,e_antic,fricas,glucose,latte_int,libnauty,lidia,lrslib,memlimit,normaliz,notedown,openssl,pandoc_attributes,pycosat,pynormaliz,rst2ipynb,sage,sage_numerical_backends_coin

gives

**********************************************************************
File "src/sage/combinat/designs/incidence_structures.py", line 2027, in sage.combinat.designs.incidence_structures.IncidenceStructure.coloring
Failed example:
    len(designs.steiner_triple_system(7).coloring())
Expected:
    3
Got:
    2
**********************************************************************

Component: combinatorics

Reviewer: David Coudert

Issue created by migration from https://trac.sagemath.org/ticket/30637

[dcoudert]

comment:1

This might be related to #29551

[slel]

comment:2

Sébastien, can you check if this also fails with bliss?

[seblabbe]

comment:3

same error with bliss installed

[seblabbe]

comment:4

With SageMath version 9.2.rc3, Release Date: 2020-10-18, I do no get the issue anymore:

$ sage -t src/sage/combinat/designs/incidence_structures.py
Running doctests with ID 2020-10-23-13-27-09-1ce86d69.
Git branch: develop
Using --optional=4ti2,build,cbc,ccache,cryptominisat,database_jones_numfield,debian,dochtml,dot2tex,e_antic,fricas,glucose,latte_int,libnauty,lidia,lrslib,memlimit,normaliz,notedown,pandoc_attributes,pip,pycosat,pynormaliz,rst2ipynb,sage,sage_numerical_backends_coin,sage_spkg
Doctesting 1 file.
sage -t --warn-long 50.5 --random-seed=0 src/sage/combinat/designs/incidence_structures.py
    [337 tests, 0.94 s]
----------------------------------------------------------------------
All tests passed!
----------------------------------------------------------------------

[dcoudert]

comment:5

no error on macOS 10.15.17 with 9.2.rc3 and bliss

sapristi:sage dcoudert$ ./sage -version
SageMath version 9.2.rc3, Release Date: 2020-10-18
sapristi:sage dcoudert$ ./sage -t --long src/sage/combinat/designs/incidence_structures.py
Running doctests with ID 2020-10-23-13-33-10-0e7e4eb3.
Git branch: develop
Using --optional=benzene,bliss,build,dochtml,homebrew,igraph,pip,plantri,python_igraph,sage,sage_numerical_backends_cplex,sage_spkg,tdlib
Doctesting 1 file.
sage -t --long --warn-long 263.3 --random-seed=0 src/sage/combinat/designs/incidence_structures.py
    [337 tests, 3.74 s]
----------------------------------------------------------------------
All tests passed!
----------------------------------------------------------------------
Total time for all tests: 3.8 seconds
    cpu time: 1.4 seconds
    cumulative wall time: 3.7 seconds

if we don't see the error anymore (don't know why), may be we can close this ticket.

[seblabbe]

comment:6

The issue has gone.

[dcoudert]

Reviewer: David Coudert

[slel]

comment:9

Follow-up at #32053.