Raise a NotImplementedError whenever an unsupported CSS pseudoclass

  is used in select(). Previously some cases did not result in a
  NotImplementedError.

4 files changed, 50 insertions, 34 deletions

diff --git a/NEWS.txt b/NEWS.txt
index bcd4223..9126ddf 100644
--- a/NEWS.txt
+++ b/NEWS.txt
@@ -9,6 +9,12 @@
   only returns the first match, instead of a list of
   matches. [bug=1349367]
 
+* You can now create a Tag object without specifying a
+  TreeBuilder. Patch by Martijn Pieters. [bug=1307471]
+
+* You can now create a NavigableString or a subclass just by invoking
+  the constructor. [bug=1294315]
+
 * Started using a standard MIT license. [bug=1294662]
 
 * Added a Chinese translation of the documentation by Delong .w.
@@ -74,11 +80,9 @@
 * Improved the exception raised when you call .unwrap() or
   .replace_with() on an element that's not attached to a tree.
 
-* You can now create a Tag object without specifying a
-  TreeBuilder. Patch by Martijn Pieters. [bug=1307471]
-
-* You can now create a NavigableString or a subclass just by invoking
-  the constructor. [bug=1294315]
+* Raise a NotImplementedError whenever an unsupported CSS pseudoclass
+  is used in select(). Previously some cases did not result in a
+  NotImplementedError.
 
 = 4.3.2 (20131002) =
 
diff --git a/bs4/element.py b/bs4/element.py
index cc21c5c..7c787b1 100644
--- a/bs4/element.py
+++ b/bs4/element.py
@@ -1336,35 +1336,38 @@ class Tag(PageElement):
                             "A pseudo-class must be prefixed with a tag name.")
                     pseudo_attributes = re.match('([a-zA-Z\d-]+)\(([a-zA-Z\d]+)\)', pseudo)
                     found = []
-                    if pseudo_attributes is not None:
+                    if pseudo_attributes is None:
+                        pseudo_type = pseudo
+                        pseudo_value = None
+                    else:
                         pseudo_type, pseudo_value = pseudo_attributes.groups()
-                        if pseudo_type == 'nth-of-type':
-                            try:
-                                pseudo_value = int(pseudo_value)
-                            except:
-                                raise NotImplementedError(
-                                    'Only numeric values are currently supported for the nth-of-type pseudo-class.')
-                            if pseudo_value < 1:
-                                raise ValueError(
-                                    'nth-of-type pseudo-class value must be at least 1.')
-                            class Counter(object):
-                                def __init__(self, destination):
-                                    self.count = 0
-                                    self.destination = destination
-
-                                def nth_child_of_type(self, tag):
-                                    self.count += 1
-                                    if self.count == self.destination:
-                                        return True
-                                    if self.count > self.destination:
-                                        # Stop the generator that's sending us
-                                        # these things.
-                                        raise StopIteration()
-                                    return False
-                            checker = Counter(pseudo_value).nth_child_of_type
-                        else:
+                    if pseudo_type == 'nth-of-type':
+                        try:
+                            pseudo_value = int(pseudo_value)
+                        except:
                             raise NotImplementedError(
-                                'Only the following pseudo-classes are implemented: nth-of-type.')
+                                'Only numeric values are currently supported for the nth-of-type pseudo-class.')
+                        if pseudo_value < 1:
+                            raise ValueError(
+                                'nth-of-type pseudo-class value must be at least 1.')
+                        class Counter(object):
+                            def __init__(self, destination):
+                                self.count = 0
+                                self.destination = destination
+
+                            def nth_child_of_type(self, tag):
+                                self.count += 1
+                                if self.count == self.destination:
+                                    return True
+                                if self.count > self.destination:
+                                    # Stop the generator that's sending us
+                                    # these things.
+                                    raise StopIteration()
+                                return False
+                        checker = Counter(pseudo_value).nth_child_of_type
+                    else:
+                        raise NotImplementedError(
+                            'Only the following pseudo-classes are implemented: nth-of-type.')
 
                 elif token == '*':
                     # Star selector -- matches everything
diff --git a/bs4/tests/test_tree.py b/bs4/tests/test_tree.py
index 6ce2a07..7edf848 100644
--- a/bs4/tests/test_tree.py
+++ b/bs4/tests/test_tree.py
@@ -1828,6 +1828,14 @@ class TestSoupSelector(TreeTest):
             ('div[data-tag]', ['data1'])
         )
 
+    def test_unsupported_pseudoclass(self):
+        self.assertRaises(
+            NotImplementedError, self.soup.select, "a:no-such-pseudoclass")
+
+        self.assertRaises(
+            NotImplementedError, self.soup.select, "a:nth-of-type(a)")
+
+
     def test_nth_of_type(self):
         # Try to select first paragraph
         els = self.soup.select('div#inner p:nth-of-type(1)')
diff --git a/doc/source/index.rst b/doc/source/index.rst
index ee68d99..f6d3e38 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -1138,8 +1138,9 @@ whose ``href`` attribute _does not_ match a regular expression::
  # [<a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>,
  #  <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>]
 
-Here's a function that returns ``True`` if a tag is surrounded by
-string objects::
+The function can be as complicated as you need it to be. Here's a
+function that returns ``True`` if a tag is surrounded by string
+objects::
 
  from bs4 import NavigableString
  def surrounded_by_strings(tag):