When running tests with --optional=sage,optional,external
$ sage -t --show-skipped --optional=sage,optional,external src/sage/graphs/graph_latex.py src/sage/databases/oeis.py src/sage/numerical/mip.pyx src/sage/misc/latex.py
the tests with labels latex,gurobi, graphviz, internet are skipped even if latex,gurobi, graphviz, internet are installed on my machine:
Running doctests with ID 2018-05-06-10-12-34-1494f13d.
Using --optional=ccache,dot2tex,external,mpir,notedown,pandoc_attributes,python2,rst2ipynb,sage
External software to be detected: cplex,gurobi,internet,latex,macaulay2,magma,maple,mathematica,matlab,octave,scilab
Doctesting 4 files.
sage -t src/sage/graphs/graph_latex.py
4 graphviz tests not run
[187 tests, 1.08 s]
sage -t src/sage/databases/oeis.py
150 internet tests not run
5 webbrowser tests not run
[118 tests, 2.28 s]
sage -t src/sage/numerical/mip.pyx
8 cplex tests not run
3 gurobi tests not run
7 other tests skipped
[616 tests, 3.69 s]
sage -t src/sage/misc/latex.py
1 imagemagick test not run
5 latex tests not run
3 other tests skipped
[315 tests, 3.00 s]
----------------------------------------------------------------------
All tests passed!
----------------------------------------------------------------------
Total time for all tests: 11.1 seconds
cpu time: 7.5 seconds
cumulative wall time: 10.1 seconds
External software detected for doctesting: gurobi,latex
