Resolved Python version inconsistencies (e.g. clear())

Details:

* Added support for the clear() method also when on Python 2.

* Enabled two testcases in the test for __contains__() that had
  been disabled for no reason.

* Moved the paragraph that already claimed that NocaseList supports
  all functionality of the built-in list as of py38 on all py versions,
  to the README and to the intro of the docs, and simplified it.

Signed-off-by: Andreas Maier <andreas.r.maier@gmx.de>

README.rst

@@ -25,8 +25,8 @@ nocaselist - A case-insensitive list for Python
 Overview
 --------
 
-Class ``NocaseList`` is a case-insensitive list that preserves
-the lexical case of its items.
+Class `NocaseList`_ is a case-insensitive list that preserves the lexical case
+of its items.
 
 Example:
 
@@ -43,6 +43,13 @@ Example:
     >>> 'ALPHA' in list1  # Any lookup or comparison is case-insensitive
     True
 
+The `NocaseList`_ class supports the functionality of the built-in
+`list class of Python 3.8`_ on all Python versions it supports (except for being
+case-insensitive, of course). This includes the ``clear()`` and ``copy()``
+methods added in Python 3.3 to the built-in ``list`` class.
+
+.. _list class of Python 3.8: https://docs.python.org/3.8/library/stdtypes.html#list
+.. _NocaseList: https://nocaselist.readthedocs.io/en/stable/reference.html#nocaselist.NocaseList
 
 Installation
 ------------

docs/changes.rst

@@ -39,6 +39,9 @@ Released: not yet
 * Docs: Switched links to items in the Python documentation to go to Python 3
   instead of Python 2.
 
+* Added support for the clear() method on Python 2.7 (where the built-in list
+  class does not support it yet). (See issue #30)
+
 * Docs: Clarified that NocaseList supports the functionality of the built-in
   list class as of Python 3.8, including all methods that have been added since
   Python 2.7, on all Python versions.

docs/intro.rst

@@ -27,6 +27,13 @@ Example:
     >>> 'ALPHA' in list1  # Any lookup or comparison is case-insensitive
     True
 
+The :class:`~nocaselist.NocaseList` class supports the functionality of the
+built-in `list class of Python 3.8`_ on all Python versions it supports (except
+for being case-insensitive, of course). This includes the ``clear()`` and
+``copy()`` methods added in Python 3.3 to the built-in ``list`` class.
+
+.. _list class of Python 3.8: https://docs.python.org/3.8/library/stdtypes.html#list
+
 
 .. _`Supported environments`:
 

nocaselist/_nocaselist.py

@@ -39,19 +39,6 @@ class NocaseList(list):
 
     The implementation maintains a second list with the lower-cased items of
     the inherited list, and ensures that both lists are in sync.
-
-    The :class:`NocaseList` class supports the functionality of the built-in
-    `list class of Python 3.8`_, so its documentation applies completely.
-    Methods that have been added to the built-in :class:`py3:list`
-    class between Python 2.7 and Python 3.8 (i.e. :meth:`~NocaseList.clear` and
-    :meth:`~NocaseList.copy`) are supported by the :class:`NocaseList` class on
-    all Python versions.
-
-    The following documentation is provided only for explicit documentation of
-    the case-insensitive behavior, and to indicate which methods have been
-    implemented for maintaining the second lower-cased list.
-
-    .. _list class of Python 3.8: https://docs.python.org/3.8/library/stdtypes.html#list
     """  # noqa E401
     # pylint: enable=line-too-long
 
@@ -345,10 +332,15 @@ def clear(self):
         """
         Remove all items from the list (and return None).
 
-        Note: This method was introduced in Python 3.
+        Note: This method is supported on Python 2 and Python 3, even though
+        the built-in list class only supports it on Python 3.
         """
-        super(NocaseList, self).clear()
-        self._lc_list.clear()
+        try:
+            super(NocaseList, self).clear()
+            self._lc_list.clear()
+        except AttributeError:
+            del self[:]
+            del self._lc_list[:]
 
     def index(self, value, start=0, stop=9223372036854775807):
         """

tests/unittest/test_nocaselist.py

@@ -23,6 +23,12 @@
 if TEST_AGAINST_LIST:
     print("\nInfo: test_nocaselist.py tests run against standard list")
 
+# Indicates that the list to be tested has a copy() method
+LIST_HAS_COPY = not TEST_AGAINST_LIST or sys.version_info[0] == 3
+
+# Indicates that the list to be tested has a clear() method
+LIST_HAS_CLEAR = not TEST_AGAINST_LIST or sys.version_info[0] == 3
+
 # The list class being tested
 # pylint: disable=invalid-name
 NocaseList = list if TEST_AGAINST_LIST else _NocaseList
@@ -749,7 +755,7 @@ def test_NocaseList_iter(testcase, nclist, exp_items):
             value='',
             exp_result=False,
         ),
-        None, None, False
+        None, None, True
     ),
     (
         "Empty list, with non-existing non-empty value (not found)",
@@ -758,7 +764,7 @@ def test_NocaseList_iter(testcase, nclist, exp_items):
             value='Dog',
             exp_result=False,
         ),
-        None, None, False
+        None, None, True
     ),
 
     # Non-empty NocaseList
@@ -1847,14 +1853,14 @@ def test_NocaseList_count(testcase, nclist, value, exp_result):
         dict(
             nclist=NocaseList(),
         ),
-        None, None, True
+        None if LIST_HAS_COPY else AttributeError, None, True
     ),
     (
         "List with two items",
         dict(
             nclist=NocaseList(['Dog', 'Cat']),
         ),
-        None, None, True
+        None if LIST_HAS_COPY else AttributeError, None, True
     ),
 ]
 
@@ -1868,9 +1874,6 @@ def test_NocaseList_copy(testcase, nclist):
     Test function for NocaseList.copy()
     """
 
-    if TEST_AGAINST_LIST:
-        pytest.skip("built-in list class does not support copy()")
-
     # The code to be tested
     nclist_copy = nclist.copy()
 
@@ -1901,14 +1904,14 @@ def test_NocaseList_copy(testcase, nclist):
         dict(
             nclist=NocaseList(),
         ),
-        None, None, True
+        None if LIST_HAS_CLEAR else AttributeError, None, True
     ),
     (
         "List with two items",
         dict(
             nclist=NocaseList(['Dog', 'Cat']),
         ),
-        None, None, True
+        None if LIST_HAS_CLEAR else AttributeError, None, True
     ),
 ]
 
@@ -1922,9 +1925,6 @@ def test_NocaseList_clear(testcase, nclist):
     Test function for NocaseList.clear()
     """
 
-    if not hasattr(list, 'clear'):
-        pytest.skip("On this Python version, list does not have clear()")
-
     # Don't change the testcase data, but a copy
     nclist_copy = NocaseList(nclist)