Merge #32637

src/sage/databases/cremona.py

@@ -1696,16 +1696,16 @@ def CremonaDatabase(name=None,mini=None,set_global=None):
 
     Verify that :trac:`12341` has been resolved::
 
-        sage: c = CremonaDatabase('should not exist',mini=True)
+        sage: c = CremonaDatabase('should not exist', mini=True)
         Traceback (most recent call last):
         ...
-        FeatureNotPresentError: Cremona's database of elliptic curves is not available.
+        FeatureNotPresentError: database_should_not_exist_ellcurve is not available.
         '...db' not found in any of [...]
         ...Further installation instructions might be available at https://github.com/JohnCremona/ecdata.
         sage: c = CremonaDatabase('should not exist',mini=False)
         Traceback (most recent call last):
         ...
-        FeatureNotPresentError: Cremona's database of elliptic curves is not available.
+        FeatureNotPresentError: database_should_not_exist_ellcurve is not available.
         '...db' not found in any of [...]
         ...Further installation instructions might be available at https://github.com/JohnCremona/ecdata.
     """

src/sage/doctest/external.py

@@ -35,10 +35,6 @@
     multiprocessing.set_start_method('fork', force=True)
 Array = multiprocessing.Array
 
-import urllib.error
-from urllib.request import Request, urlopen
-from ssl import SSLContext
-
 # Functions in this module whose name is of the form 'has_xxx' tests if the
 # software xxx is available to Sage.
 prefix = 'has_'
@@ -53,15 +49,11 @@ def has_internet():
     EXAMPLES::
 
         sage: from sage.doctest.external import has_internet
-        sage: has_internet() # random, optional -- internet
-        True
+        sage: has_internet()                                 # random, optional -- internet
+        FeatureTestResult('internet', True)
     """
-    req = Request("https://www.sagemath.org",headers={"User-Agent":"sage-doctest"})
-    try:
-        urlopen(req, timeout=1, context=SSLContext())
-        return True
-    except urllib.error.URLError:
-        return False
+    from sage.features.internet import Internet
+    return Internet().is_present()
 
 def has_latex():
     """
@@ -195,7 +187,7 @@ def has_pandoc():
 
         sage: from sage.doctest.external import has_pandoc
         sage: has_pandoc()      # optional -- pandoc
-        FeatureTestResult('Pandoc', True)
+        FeatureTestResult('pandoc', True)
     """
     from sage.features.pandoc import Pandoc
     return Pandoc().is_present()
@@ -225,14 +217,10 @@ def has_cplex():
 
         sage: from sage.doctest.external import has_cplex
         sage: has_cplex() # random, optional - CPLEX
-        True
+        FeatureTestResult('cplex', True)
     """
-    from sage.numerical.mip import MixedIntegerLinearProgram
-    try:
-        MixedIntegerLinearProgram(solver='cplex')
-        return True
-    except Exception:
-        return False
+    from sage.features.mip_backends import CPLEX
+    return CPLEX().is_present()
 
 def has_gurobi():
     """
@@ -242,14 +230,10 @@ def has_gurobi():
 
         sage: from sage.doctest.external import has_gurobi
         sage: has_gurobi() # random, optional - Gurobi
-        True
+        FeatureTestResult('gurobi', True)
     """
-    from sage.numerical.mip import MixedIntegerLinearProgram
-    try:
-        MixedIntegerLinearProgram(solver='gurobi')
-        return True
-    except Exception:
-        return False
+    from sage.features.mip_backends import Gurobi
+    return Gurobi().is_present()
 
 def has_graphviz():
     """
@@ -259,7 +243,7 @@ def has_graphviz():
 
         sage: from sage.doctest.external import has_graphviz
         sage: has_graphviz()   # optional -- graphviz
-        FeatureTestResult('Graphviz', True)
+        FeatureTestResult('graphviz', True)
     """
     from sage.features.graphviz import Graphviz
     return Graphviz().is_present()
@@ -272,7 +256,7 @@ def has_ffmpeg():
 
         sage: from sage.doctest.external import has_ffmpeg
         sage: has_ffmpeg()      # optional -- ffmpeg
-        FeatureTestResult('FFmpeg', True)
+        FeatureTestResult('ffmpeg', True)
     """
     from sage.features.ffmpeg import FFmpeg
     return FFmpeg().is_present()
@@ -285,7 +269,7 @@ def has_imagemagick():
 
         sage: from sage.doctest.external import has_imagemagick
         sage: has_imagemagick() # optional -- imagemagick
-        FeatureTestResult('convert', True)
+        FeatureTestResult('imagemagick', True)
     """
     from sage.features.imagemagick import ImageMagick
     return ImageMagick().is_present()
@@ -299,7 +283,7 @@ def has_rubiks():
 
         sage: from sage.doctest.external import has_rubiks
         sage: has_rubiks()   # optional -- rubiks
-        FeatureTestResult('Rubiks', True)
+        FeatureTestResult('rubiks', True)
     """
     from sage.features.rubiks import Rubiks
     return Rubiks().is_present()

src/sage/features/__init__.py

@@ -28,7 +28,7 @@
 
     sage: from sage.features.gap import GapPackage
     sage: GapPackage("grape", spkg="gap_packages").is_present()  # optional: gap_packages
-    FeatureTestResult('GAP package grape', True)
+    FeatureTestResult('gap_package_grape', True)
 
 Note that a :class:`FeatureTestResult` acts like a bool in most contexts::
 
@@ -92,20 +92,32 @@ class Feature(TrivialUniqueRepresentation):
     r"""
     A feature of the runtime environment
 
+    INPUT:
+
+    - ``name`` -- (string) name of the feature; this should be suitable as an optional tag
+      for the Sage doctester, i.e., lowercase alphanumeric with underscores (``_``) allowed;
+      features that correspond to Python modules/packages may use periods (``.``)
+
+    - ``spkg`` -- (string) name of the SPKG providing the feature
+
+    - ``description`` -- (string) optional; plain English description of the feature
+
+    - ``url`` -- a URL for the upstream package providing the feature
+
     Overwrite :meth:`_is_present` to add feature checks.
 
     EXAMPLES::
 
         sage: from sage.features.gap import GapPackage
         sage: GapPackage("grape", spkg="gap_packages")  # indirect doctest
-        Feature('GAP package grape')
+        Feature('gap_package_grape')
 
     For efficiency, features are unique::
 
         sage: GapPackage("grape") is GapPackage("grape")
         True
     """
-    def __init__(self, name, spkg=None, url=None):
+    def __init__(self, name, spkg=None, url=None, description=None):
         r"""
         TESTS::
 
@@ -117,6 +129,8 @@ def __init__(self, name, spkg=None, url=None):
         self.name = name
         self.spkg = spkg
         self.url = url
+        self.description = description
+
         self._cache_is_present = None
         self._cache_resolution = None
 
@@ -133,9 +147,9 @@ def is_present(self):
 
             sage: from sage.features.gap import GapPackage
             sage: GapPackage("grape", spkg="gap_packages").is_present()  # optional: gap_packages
-            FeatureTestResult('GAP package grape', True)
+            FeatureTestResult('gap_package_grape', True)
             sage: GapPackage("NOT_A_PACKAGE", spkg="gap_packages").is_present()
-            FeatureTestResult('GAP package NOT_A_PACKAGE', False)
+            FeatureTestResult('gap_package_NOT_A_PACKAGE', False)
 
         The result is cached::
 
@@ -183,7 +197,7 @@ def require(self):
             sage: GapPackage("ve1EeThu").require()
             Traceback (most recent call last):
             ...
-            FeatureNotPresentError: GAP package ve1EeThu is not available.
+            FeatureNotPresentError: gap_package_ve1EeThu is not available.
             `TestPackageAvailability("ve1EeThu")` evaluated to `fail` in GAP.
         """
         presence = self.is_present()
@@ -198,9 +212,14 @@ def __repr__(self):
 
             sage: from sage.features.gap import GapPackage
             sage: GapPackage("grape")  # indirect doctest
-            Feature('GAP package grape')
+            Feature('gap_package_grape')
+
+            sage: from sage.features.databases import DatabaseConwayPolynomials
+            sage: DatabaseConwayPolynomials()  # indirect doctest
+            Feature('conway_polynomials': Frank Luebeck's database of Conway polynomials)
         """
-        return 'Feature({name!r})'.format(name=self.name)
+        description = f'{self.name!r}: {self.description}' if self.description else f'{self.name!r}'
+        return f'Feature({description})'
 
     def resolution(self):
         r"""
@@ -263,7 +282,7 @@ def __str__(self):
             sage: GapPackage("gapZuHoh8Uu").require()  # indirect doctest
             Traceback (most recent call last):
             ...
-            FeatureNotPresentError: GAP package gapZuHoh8Uu is not available.
+            FeatureNotPresentError: gap_package_gapZuHoh8Uu is not available.
             `TestPackageAvailability("gapZuHoh8Uu")` evaluated to `fail` in GAP.
         """
         lines = ["{feature} is not available.".format(feature=self.feature.name)]
@@ -285,7 +304,7 @@ class FeatureTestResult(object):
 
         sage: from sage.features.gap import GapPackage
         sage: presence = GapPackage("NOT_A_PACKAGE").is_present(); presence  # indirect doctest
-        FeatureTestResult('GAP package NOT_A_PACKAGE', False)
+        FeatureTestResult('gap_package_NOT_A_PACKAGE', False)
         sage: bool(presence)
         False
 
@@ -304,9 +323,9 @@ class FeatureTestResult(object):
         sage: from sage.features import FeatureTestResult
         sage: package = GapPackage("NOT_A_PACKAGE", spkg="no_package")
         sage: str(FeatureTestResult(package, True).resolution)  # optional - sage_spkg
-        '...To install GAP package NOT_A_PACKAGE...you can try to run...sage -i no_package...'
+        '...To install gap_package_NOT_A_PACKAGE...you can try to run...sage -i no_package...'
         sage: str(FeatureTestResult(package, False).resolution) # optional - sage_spkg
-        '...To install GAP package NOT_A_PACKAGE...you can try to run...sage -i no_package...'
+        '...To install gap_package_NOT_A_PACKAGE...you can try to run...sage -i no_package...'
         sage: FeatureTestResult(package, False, resolution="rtm").resolution
         'rtm'
     """
@@ -801,8 +820,8 @@ def __init__(self, name, **kwds):
         TESTS::
 
             sage: from sage.features import PythonModule
-            sage: from sage.features.fes import LibFES
-            sage: isinstance(LibFES(), PythonModule)  # indirect doctest
+            sage: from sage.features.databases import DatabaseKnotInfo
+            sage: isinstance(DatabaseKnotInfo(), PythonModule)  # indirect doctest
             True
         """
         Feature.__init__(self, name, **kwds)

src/sage/features/csdp.py

@@ -20,7 +20,7 @@ class CSDP(Executable):
 
         sage: from sage.features.csdp import CSDP
         sage: CSDP().is_present()  # optional: csdp
-        FeatureTestResult('CSDP', True)
+        FeatureTestResult('csdp', True)
     """
     def __init__(self):
         r"""
@@ -30,7 +30,7 @@ def __init__(self):
             sage: isinstance(CSDP(), CSDP)
             True
         """
-        Executable.__init__(self, name="CSDP", spkg="csdp", executable="theta",
+        Executable.__init__(self, name="csdp", spkg="csdp", executable="theta",
                                 url="https://github.com/dimpase/csdp")
 
     def is_functional(self):
@@ -41,7 +41,7 @@ def is_functional(self):
 
             sage: from sage.features.csdp import CSDP
             sage: CSDP().is_functional()  # optional: csdp
-            FeatureTestResult('CSDP', True)
+            FeatureTestResult('csdp', True)
         """
         from sage.misc.temporary_file import tmp_filename
         tf_name = tmp_filename()

src/sage/features/databases.py

@@ -19,7 +19,7 @@ class DatabaseConwayPolynomials(StaticFile):
 
         sage: from sage.features.databases import DatabaseConwayPolynomials
         sage: DatabaseConwayPolynomials().is_present()
-        FeatureTestResult("Frank Luebeck's database of Conway polynomials", True)
+        FeatureTestResult('conway_polynomials', True)
     """
 
     def __init__(self):
@@ -34,10 +34,11 @@ def __init__(self):
             search_path = [CONWAY_POLYNOMIALS_DATA_DIR]
         else:
             search_path = []
-        StaticFile.__init__(self, "Frank Luebeck's database of Conway polynomials",
+        StaticFile.__init__(self, "conway_polynomials",
                             filename='conway_polynomials.p',
                             search_path=search_path,
-                            spkg='conway_polynomials')
+                            spkg='conway_polynomials',
+                            description="Frank Luebeck's database of Conway polynomials")
 
 
 CREMONA_DATA_DIRS = set([CREMONA_MINI_DATA_DIR, CREMONA_LARGE_DATA_DIR])
@@ -57,9 +58,9 @@ class DatabaseCremona(StaticFile):
 
         sage: from sage.features.databases import DatabaseCremona
         sage: DatabaseCremona('cremona_mini').is_present()
-        FeatureTestResult("Cremona's database of elliptic curves", True)
+        FeatureTestResult('database_cremona_mini_ellcurve', True)
         sage: DatabaseCremona().is_present()  # optional: database_cremona_ellcurve
-        FeatureTestResult("Cremona's database of elliptic curves", True)
+        FeatureTestResult('database_cremona_ellcurve', True)
     """
     def __init__(self, name="cremona", spkg="database_cremona_ellcurve"):
         r"""
@@ -69,11 +70,12 @@ def __init__(self, name="cremona", spkg="database_cremona_ellcurve"):
             sage: isinstance(DatabaseCremona(), DatabaseCremona)
             True
         """
-        StaticFile.__init__(self, "Cremona's database of elliptic curves",
+        StaticFile.__init__(self, f"database_{name}_ellcurve",
                             filename='{}.db'.format(name.replace(' ', '_')),
                             search_path=CREMONA_DATA_DIRS,
                             spkg=spkg,
-                            url="https://github.com/JohnCremona/ecdata")
+                            url="https://github.com/JohnCremona/ecdata",
+                            description="Cremona's database of elliptic curves")
 
 
 class DatabaseJones(StaticFile):
@@ -94,9 +96,10 @@ def __init__(self):
             sage: isinstance(DatabaseJones(), DatabaseJones)
             True
         """
-        StaticFile.__init__(self, "John Jones's tables of number fields",
+        StaticFile.__init__(self, "database_jones_numfield",
                             filename='jones/jones.sobj',
-                            spkg="database_jones_numfield")
+                            spkg="database_jones_numfield",
+                            description="John Jones's tables of number fields")
 
 
 class DatabaseKnotInfo(PythonModule):

src/sage/features/fes.py

@@ -4,6 +4,8 @@
 """
 
 from . import CythonFeature, PythonModule
+from .join_feature import JoinFeature
+
 
 TEST_CODE = """
 # distutils: libraries=fes
@@ -70,7 +72,7 @@ def __init__(self):
                                url="http://www.lifl.fr/~bouillag/fes/")
 
 
-class LibFES(PythonModule):
+class LibFES(JoinFeature):
     r"""
     A :class:`Feature` which describes whether the :mod:`sage.libs.fes`
     module has been enabled for this build of Sage and is functional.
@@ -88,5 +90,7 @@ def __init__(self):
             sage: isinstance(LibFES(), LibFES)
             True
         """
-        PythonModule.__init__(self, "sage.libs.fes", spkg="fes",
-                              url="http://www.lifl.fr/~bouillag/fes/")
+        JoinFeature.__init__(self, 'fes',
+                             [PythonModule("sage.libs.fes")],
+                             spkg="fes",
+                             url="http://www.lifl.fr/~bouillag/fes/")

src/sage/features/ffmpeg.py

@@ -23,7 +23,7 @@ class FFmpeg(Executable):
 
         sage: from sage.features.ffmpeg import FFmpeg
         sage: FFmpeg().is_present()  # optional: ffmpeg
-        FeatureTestResult('FFmpeg', True)
+        FeatureTestResult('ffmpeg', True)
     """
     def __init__(self):
         r"""
@@ -33,5 +33,5 @@ def __init__(self):
             sage: isinstance(FFmpeg(), FFmpeg)
             True
         """
-        Executable.__init__(self, "FFmpeg", executable="ffmpeg",
+        Executable.__init__(self, "ffmpeg", executable="ffmpeg",
                             url="https://www.ffmpeg.org/")