natcmp does not appear in Python 3 anymore.

5 files changed, 76 insertions, 52 deletions

diff --git a/natsort/__init__.py b/natsort/__init__.py
index 3fe1c9f..45ede6e 100644
--- a/natsort/__init__.py
+++ b/natsort/__init__.py
@@ -7,6 +7,11 @@ from __future__ import (
 )
 
 # Local imports.
+import sys
+
+from natsort.utils import chain_functions
+from natsort._version import __version__
+
 from natsort.natsort import (
     natsort_key,
     natsort_keygen,
@@ -23,10 +28,10 @@ from natsort.natsort import (
     as_ascii,
     as_utf8,
     ns,
-    natcmp,
 )
-from natsort.utils import chain_functions
-from natsort._version import __version__
+
+if float(sys.version[:3]) < 3:
+    from natsort.natsort import natcmp
 
 __all__ = [
     'natsort_key',
diff --git a/natsort/compat/py23.py b/natsort/compat/py23.py
index 8155798..fa56b06 100644
--- a/natsort/compat/py23.py
+++ b/natsort/compat/py23.py
@@ -30,6 +30,13 @@ py23_basestring = str if sys.version[0] == '3' else basestring
 # unichr function
 py23_unichr = chr if sys.version[0] == '3' else unichr
 
+
+def _py23_cmp(a, b):
+    return (a > b) - (a < b)
+
+
+py23_cmp = _py23_cmp if sys.version[0] == '3' else cmp
+
 # zip as an iterator
 if sys.version[0] == '3':
     py23_zip = zip
diff --git a/natsort/natsort.py b/natsort/natsort.py
index 53e5054..20d3ea0 100644
--- a/natsort/natsort.py
+++ b/natsort/natsort.py
@@ -23,12 +23,14 @@ from functools import partial
 from warnings import warn
 
 # Local imports.
+import sys
+
 import natsort.compat.locale
 from natsort.ns_enum import ns
 from natsort.compat.py23 import (
     u_format,
     py23_str,
-)
+    py23_cmp)
 from natsort.utils import (
     _natsort_key,
     _args_to_enum,
@@ -675,41 +677,41 @@ def order_by_index(seq, index, iter=False):
     """
     return (seq[i] for i in index) if iter else [seq[i] for i in index]
 
-
-def natcmp(x, y, alg=0, **kwargs):
-    """
-    Compare two objects using a key and an algorithm.
-
-    Parameters
-    ----------
-    x : object
-        First object to compare.
-
-    y : object
-        Second object to compare.
-
-    alg : ns enum, optional
-        This option is used to control which algorithm `natsort`
-        uses when sorting. For details into these options, please see
-        the :class:`ns` class documentation. The default is `ns.INT`.
-
-    Returns
-    -------
-    out: int
-        0 if x and y are equal, 1 if x > y, -1 if y > x.
-
-    See Also
-    --------
-    natsort_keygen : Generates the key that makes natural sorting possible.
-
-    Examples
-    --------
-    Use `natcmp` just like the builtin `cmp`::
-
-        >>> one = 1
-        >>> two = 2
-        >>> natcmp(one, two)
-        -1
-    """
-    key = natsort_keygen(alg=alg, **kwargs)
-    return (key(x) > key(y)) - (key(x) < key(y))
+if float(sys.version[:3]) < 3:
+    def natcmp(x, y, alg=0, **kwargs):
+        """
+        Compare two objects using a key and an algorithm.
+
+        Parameters
+        ----------
+        x : object
+            First object to compare.
+
+        y : object
+            Second object to compare.
+
+        alg : ns enum, optional
+            This option is used to control which algorithm `natsort`
+            uses when sorting. For details into these options, please see
+            the :class:`ns` class documentation. The default is `ns.INT`.
+
+        Returns
+        -------
+        out: int
+            0 if x and y are equal, 1 if x > y, -1 if y > x.
+
+        See Also
+        --------
+        natsort_keygen : Generates a key that makes natural sorting possible.
+
+        Examples
+        --------
+        Use `natcmp` just like the builtin `cmp`::
+
+            >>> one = 1
+            >>> two = 2
+            >>> natcmp(one, two)
+            -1
+        """
+        key = natsort_keygen(alg=alg, **kwargs)
+        return py23_cmp(key(x), key(y))
diff --git a/test_natsort/test_natsort_cmp.py b/test_natsort/test_natsort_cmp.py
index 2dbf6b5..74bb61b 100644
--- a/test_natsort/test_natsort_cmp.py
+++ b/test_natsort/test_natsort_cmp.py
@@ -1,6 +1,9 @@
 # -*- coding: utf-8 -*-
 # pylint: disable=unused-variable
-"""These test the natcmp() function."""
+"""These test the natcmp() function.
+
+Note that these tests are only relevant for Python version < 3.
+"""
 import sys
 from functools import partial
 
@@ -8,14 +11,14 @@ import pytest
 from hypothesis import given
 from hypothesis.strategies import floats, integers, lists
 
-from natsort import natcmp, ns
+from natsort import ns
 
-PY_VERSION = float(sys.version[:3])
+from natsort.compat.py23 import py23_cmp
 
+PY_VERSION = float(sys.version[:3])
 
-if PY_VERSION >= 3.0:
-    def cmp(a, b):
-        return (a > b) - (a < b)
+if PY_VERSION < 3:
+    from natsort import natcmp
 
 
 class Comparable(object):
@@ -48,13 +51,13 @@ def test__classes_can_utilize_max_or_min():
 @pytest.mark.skipif(PY_VERSION >= 3.0, reason='cmp() deprecated in Python 3')
 @given(integers(), integers())
 def test__natcmp_works_the_same_for_integers_as_cmp(x, y):
-    assert cmp(x, y) == natcmp(x, y)
+    assert py23_cmp(x, y) == natcmp(x, y)
 
 
 @pytest.mark.skipif(PY_VERSION >= 3.0, reason='cmp() deprecated in Python 3')
 @given(floats(allow_nan=False), floats(allow_nan=False))
 def test__natcmp_works_the_same_for_floats_as_cmp(x, y):
-    assert cmp(x, y) == natcmp(x, y)
+    assert py23_cmp(x, y) == natcmp(x, y)
 
 
 @pytest.mark.skipif(PY_VERSION >= 3.0, reason='cmp() deprecated in Python 3')
@@ -63,4 +66,4 @@ def test_sort_strings_with_numbers(a_list):
     strings = map(str, a_list)
     natcmp_sorted = sorted(strings, cmp=partial(natcmp, alg=ns.REAL))
 
-    assert sorted(a_list) == map(int, natcmp_sorted)
+    assert sorted(a_list) == [int(var) for var in natcmp_sorted]
diff --git a/test_natsort/test_utils.py b/test_natsort/test_utils.py
index f1cffa2..d472702 100644
--- a/test_natsort/test_utils.py
+++ b/test_natsort/test_utils.py
@@ -23,7 +23,7 @@ from natsort.utils import (
     _groupletters,
     chain_functions,
 )
-from natsort.compat.py23 import py23_str
+from natsort.compat.py23 import py23_str, py23_cmp
 from natsort.compat.locale import null_string
 from slow_splitters import (
     sep_inserter,
@@ -232,3 +232,10 @@ def test_path_splitter_splits_path_string_by_separator_and_removes_extension(x):
     z = py23_str(pathlib.Path(*x[:-2])) + '.' + x[-1]
     y = tuple(pathlib.Path(z).parts)
     assert tuple(_path_splitter(z)) == y[:-1] + (pathlib.Path(z).stem, pathlib.Path(z).suffix)
+
+
+@given(integers())
+def test_py23_cmp(x):
+    assert py23_cmp(x, x) == 0
+    assert py23_cmp(x, x + 1) < 0
+    assert py23_cmp(x, x - 1) > 0