isup: don't assume .com any more if dot is missing

The "com" TLD is nowhere near as common as it once was. It's probably
better to just inform the user that they forgot a dot, or tried to look
up a local (unqualified) name that Sopel won't be able to access.

Sopel definitely shouldn't just skip enforcing the presence of a dot,
since LAN names' existence shouldn't be accessible this way. Left a TODO
comment about mitigating this kind of risk.

sopel/modules/isup.py

@@ -27,7 +27,7 @@ def get_site_url(site):
     or a :exc:`ValueError` is raised.
 
     If the ``site`` does not have a scheme, ``http`` is used. If it doesn't
-    have a TLD, ``.com`` is used.
+    have a TLD, a :exc:`ValueError` is raised.
     """
     site = site.strip() if site else ''
     if not site:
@@ -41,7 +41,9 @@ def get_site_url(site):
         site = 'http://' + site
 
     if '.' not in site:
-        site += ".com"
+        # TODO: Make this more robust against e.g.
+        # .isup lanpeer/path/to/some/IoT.service
+        raise ValueError('I need a fully qualified domain name (with a dot).')
 
     return site
 

test/modules/test_modules_isup.py

@@ -8,8 +8,6 @@
 
 
 VALID_SITE_URLS = (
-    # no TLD, no scheme
-    ('example', 'http://example.com'),
     # no scheme
     ('www.example.com', 'http://www.example.com'),
     # with scheme
@@ -37,6 +35,7 @@ def test_get_site_url(site, expected):
     '      ',  # empty once stripped
     'steam://browsemedia',  # invalid protocol
     '://',  # invalid protocol (that's a weird one)
+    'example',  # no TLD, no scheme
 )