sage.doctest.external.has_internet: Refactor through new Feature

src/sage/doctest/external.py

@@ -53,15 +53,11 @@ 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():
     """

src/sage/features/internet.py

@@ -0,0 +1,47 @@
+from . import Feature, FeatureTestResult
+
+
+class Internet(Feature):
+    r"""
+    A feature describing if Internet is available.
+
+    Failure of connecting to the site "https://www.sagemath.org" within a second
+    is regarded as internet being not available.
+
+    EXAMPLES::
+
+        sage: from sage.features.internet import Internet
+        sage: Internet()
+        Feature('internet')
+    """
+
+    def __init__(self):
+        r"""
+        TESTS::
+
+            sage: from sage.features.internet import Internet
+            sage: Internet() is Internet()
+            True
+        """
+        Feature.__init__(self, 'internet')
+
+    def _is_present(self):
+        r"""
+        Test whether Internet is available.
+
+        EXAMPLES::
+
+            sage: from sage.features.internet import Internet
+            sage: Internet().is_present()          # random, optional -- internet
+            FeatureTestResult('internet', True)
+        """
+        import urllib.error
+        from urllib.request import Request, urlopen
+        from ssl import SSLContext
+
+        req = Request("https://www.sagemath.org", headers={"User-Agent": "sage-doctest"})
+        try:
+            urlopen(req, timeout=1, context=SSLContext())
+            return FeatureTestResult(self, True)
+        except urllib.error.URLError:
+            return FeatureTestResult(self, False)