Trac #25308: sage -t --show-skipped says "5 latex tests not run" whil…

…e they are

First I add a problem in the output of a `#optional - latex` doctest:
{{{
#!diff
diff --git a/src/sage/misc/latex.py b/src/sage/misc/latex.py
index 4771a1c..01e9cb4 100644
--- a/src/sage/misc/latex.py
+++ b/src/sage/misc/latex.py
@@ -1548,7 +1548,7 @@ Warning: `{}` is not part of this computer's TeX
installation.""".format(file_na
             sage: latex.add_package_to_preamble_if_available("xypic")
             sage:
latex.add_package_to_preamble_if_available("nonexistent_package")
             sage: latex.extra_preamble()       # optional - latex
-            '\\usepackage{xypic}\n'
+            '\\usepackage{xypic}\n' PROBLEM
             sage: latex.extra_preamble('')
         """
         assert isinstance(package_name, str)
}}}

Then this is OK:

{{{
$ sage -t --show-skipped src/sage/misc/latex.py
Using --optional=ccache,dot2tex,mpir,notedown,pandoc_attributes,python2,
rst2ipynb,sage
Doctesting 1 file.
sage -t src/sage/misc/latex.py
    1 imagemagick test not run
    5 latex tests not run
    3 other tests skipped
    [310 tests, 1.23 s]
----------------------------------------------------------------------
All tests passed!
----------------------------------------------------------------------
}}}

Then, writing `--optional=sage,external` detects that `latex` is
available and runs the 5  `latex` optional tests (total number of tests
goes from 310 to 315).

{{{
$ sage -t --show-skipped --optional=sage,external src/sage/misc/latex.py
Using --optional=external,sage
External software to be detected: cplex,gurobi,internet,latex,macaulay2,
magma,maple,mathematica,matlab,octave,scilab
Doctesting 1 file.
sage -t src/sage/misc/latex.py
**********************************************************************
File "src/sage/misc/latex.py", line 1550, in
sage.misc.latex.Latex.add_package_to_preamble_if_available
Failed example:
    latex.extra_preamble()       # optional - latex
Expected:
    '\\usepackage{xypic}\n' PROBLEM
Got:
    '\\usepackage{xypic}\n'
**********************************************************************
1 item had failures:
   1 of   5 in
sage.misc.latex.Latex.add_package_to_preamble_if_available
    1 imagemagick test not run
    5 latex tests not run
    3 other tests skipped
    [315 tests, 1 failure, 1.55 s]
----------------------------------------------------------------------
sage -t src/sage/misc/latex.py  # 1 doctest failed
----------------------------------------------------------------------
Total time for all tests: 1.8 seconds
    cpu time: 0.6 seconds
    cumulative wall time: 1.5 seconds
External software detected for doctesting: latex
}}}

But `--show-skipped` still says that `5 latex tests not run`.

URL: https://trac.sagemath.org/25308
Reported by: slabbe
Ticket author(s): Sébastien Labbé
Reviewer(s): Vincent Klein

src/sage/doctest/reporting.py

@@ -39,6 +39,7 @@
 from sage.structure.sage_object import SageObject
 from sage.doctest.util import count_noun
 from sage.doctest.sources import DictAsObject
+from .external import available_software
 
 def signal_name(sig):
     """
@@ -112,6 +113,39 @@ def __init__(self, controller):
         self.stats = {}
         self.error_status = 0
 
+    def have_optional_tag(self, tag):
+        r"""
+        Return whether doctests marked with this tag are run.
+
+        INPUT:
+
+        - ``tag`` -- string
+
+        EXAMPLES::
+
+            sage: from sage.doctest.reporting import DocTestReporter
+            sage: from sage.doctest.control import DocTestController, DocTestDefaults
+            sage: from sage.env import SAGE_SRC
+            sage: import os
+            sage: filename = os.path.join(SAGE_SRC,'sage','doctest','reporting.py')
+            sage: DC = DocTestController(DocTestDefaults(),[filename])
+            sage: DTR = DocTestReporter(DC)
+
+        ::
+
+            sage: DTR.have_optional_tag('sage')
+            True
+            sage: DTR.have_optional_tag('nice_unavailable_package')
+            False
+
+        """
+        if tag in self.controller.options.optional:
+            return True
+        if 'external' in self.controller.options.optional:
+            if tag in available_software.seen():
+                return True
+        return False
+
     def report_head(self, source):
         """
         Return the "sage -t [options] file.py" line as string.
@@ -453,15 +487,14 @@ def report(self, source, timeout, return_code, results, output, pid=None):
                                         log("    %s not run"%(count_noun(nskipped, "long test")))
                                 elif tag in ("not tested", "not implemented"):
                                     untested += nskipped
-                                else:
-                                    if tag not in self.controller.options.optional:
-                                        seen_other = True
-                                        if tag == "bug":
-                                            log("    %s not run due to known bugs"%(count_noun(nskipped, "test")))
-                                        elif tag == "":
-                                            log("    %s not run"%(count_noun(nskipped, "unlabeled test")))
-                                        else:
-                                            log("    %s not run"%(count_noun(nskipped, tag + " test")))
+                                elif not self.have_optional_tag(tag):
+                                    seen_other = True
+                                    if tag == "bug":
+                                        log("    %s not run due to known bugs"%(count_noun(nskipped, "test")))
+                                    elif tag == "":
+                                        log("    %s not run"%(count_noun(nskipped, "unlabeled test")))
+                                    else:
+                                        log("    %s not run"%(count_noun(nskipped, tag + " test")))
                             if untested:
                                 log("    %s skipped"%(count_noun(untested, "%stest"%("other " if seen_other else ""))))
                     if not (self.controller.options.only_errors and not f):