Add utils.raises. Closes #274.

qutebrowser/test/utils/test_utils.py

@@ -340,5 +340,46 @@ class IsEnumTests(unittest.TestCase):
         self.assertFalse(utils.is_enum(23))
 
 
+class RaisesTests(unittest.TestCase):
+
+    """Test raises."""
+
+    def do_raise(self):
+        raise Exception
+
+    def do_nothing(self):
+        pass
+
+    def test_raises_single_exc_true(self):
+        """Test raises with a single exception which gets raised."""
+        self.assertTrue(utils.raises(ValueError, int, 'a'))
+
+    def test_raises_single_exc_false(self):
+        """Test raises with a single exception which does not get raised."""
+        self.assertFalse(utils.raises(ValueError, int, '1'))
+
+    def test_raises_multiple_exc_true(self):
+        """Test raises with multiple exceptions which get raised."""
+        self.assertTrue(utils.raises((ValueError, TypeError), int, 'a'))
+        self.assertTrue(utils.raises((ValueError, TypeError), int, None))
+
+    def test_raises_multiple_exc_false(self):
+        """Test raises with multiple exceptions which do not get raised."""
+        self.assertFalse(utils.raises((ValueError, TypeError), int, '1'))
+
+    def test_no_args(self):
+        """Test with no args and an exception which gets raised."""
+        self.assertTrue(utils.raises(Exception, self.do_raise))
+
+    def test_no_args(self):
+        """Test with no args and an exception which does not get raised."""
+        self.assertFalse(utils.raises(Exception, self.do_nothing))
+
+    def test_unrelated_exception(self):
+        """Test with an unrelated exception."""
+        with self.assertRaises(Exception):
+            utils.raises(ValueError, self.do_raise)
+
+
 if __name__ == '__main__':
     unittest.main()

qutebrowser/utils/urlutils.py

@@ -28,7 +28,7 @@ from PyQt5.QtCore import QUrl
 from PyQt5.QtNetwork import QHostInfo
 
 from qutebrowser.config import config
-from qutebrowser.utils import log, qtutils, message
+from qutebrowser.utils import log, qtutils, message, utils
 from qutebrowser.commands import cmdexc
 
 
@@ -68,18 +68,6 @@ def _get_search_url(txt):
     return url
 
 
-def _is_numeric(s):
-    """Check if the given string is some valid number."""
-    try:
-        int(s, 0)
-    except ValueError:
-        try:
-            float(s)
-        except ValueError:
-            return False
-    return True
-
-
 def _is_url_naive(urlstr):
     """Naive check if given URL is really a URL.
 
@@ -101,7 +89,8 @@ def _is_url_naive(urlstr):
     # Qt treats things like "23.42" or "1337" or "0xDEAD" as valid URLs
     # which we don't want to. Note we already filtered *real* valid IPs
     # above.
-    if _is_numeric(urlstr):
+    if ((not utils.raises(ValueError, int, urlstr, 0)) or
+            (not utils.raises(ValueError, float, urlstr))):
         return False
 
     if not url.isValid():

qutebrowser/utils/utils.py

@@ -544,3 +544,22 @@ def qualname(obj):
         return "{}.{}".format(obj.__module__, name)
     else:
         return name
+
+
+def raises(exc, func, *args):
+    """Check if a function raises a given exception.
+
+    Args:
+        exc: A single exception or an iterable of exceptions.
+        func: A function to call.
+        *args: The arguments to pass to the function.
+
+    Returns:
+        True if the exception was raised, False otherwise.
+    """
+    try:
+        func(*args)
+    except exc:
+        return True
+    else:
+        return False