Add tests for ChainMap (issue #226)

Author: edschofield

tests/test_future/test_chainmap.py

@@ -0,0 +1,160 @@
+"""
+Tests for the future.standard_library module
+"""
+
+from __future__ import absolute_import, print_function
+from future import standard_library
+from future import utils
+from future.tests.base import unittest, CodeHandler, expectedFailurePY2
+
+import sys
+import tempfile
+import os
+import copy
+import textwrap
+from subprocess import CalledProcessError
+
+
+class TestChainMap(CodeHandler):
+
+    def setUp(self):
+        self.interpreter = sys.executable
+        standard_library.install_aliases()
+        super(TestChainMap, self).setUp()
+
+    def tearDown(self):
+        # standard_library.remove_hooks()
+        pass
+
+    @staticmethod
+    def simple_cm():
+        from collections import ChainMap
+        c = ChainMap()
+        c['one'] = 1
+        c['two'] = 2
+    
+        cc = c.new_child()
+        cc['one'] = 'one'
+    
+        return c, cc
+    
+    
+    def test_repr(self):
+        c, cc = TestChainMap.simple_cm()
+    
+        order1 = "ChainMap({'one': 'one'}, {'one': 1, 'two': 2})"
+        order2 = "ChainMap({'one': 'one'}, {'two': 2, 'one': 1})"
+        assert repr(cc) in [order1, order2]
+    
+    
+    def test_recursive_repr(self):
+        """
+        Test for degnerative recursive cases. Very unlikely in
+        ChainMaps. But all must bow before the god of testing coverage.
+        """
+        from collections import ChainMap
+        c = ChainMap()
+        c['one'] = c
+        assert repr(c) == "ChainMap({'one': ...})"
+    
+    
+    def test_get(self):
+        c, cc = TestChainMap.simple_cm()
+    
+        assert cc.get('two') == 2
+        assert cc.get('three') == None
+        assert cc.get('three', 'notthree') == 'notthree'
+    
+    
+    def test_bool(self):
+        from collections import ChainMap
+        c = ChainMap()
+        assert not(bool(c))
+    
+        c['one'] = 1
+        c['two'] = 2
+        assert bool(c)
+    
+        cc = c.new_child()
+        cc['one'] = 'one'
+        assert cc
+    
+    
+    def test_fromkeys(self):
+        from collections import ChainMap
+        keys = 'a b c'.split()
+        c = ChainMap.fromkeys(keys)
+        assert len(c) == 3
+        assert c['a'] == None
+        assert c['b'] == None
+        assert c['c'] == None
+    
+    
+    def test_copy(self):
+        c, cc = TestChainMap.simple_cm()
+        new_cc = cc.copy()
+        assert new_cc is not cc
+        assert sorted(new_cc.items()) == sorted(cc.items())
+    
+    
+    def test_parents(self):
+        c, cc = TestChainMap.simple_cm()
+    
+        new_c = cc.parents
+        assert c is not new_c
+        assert len(new_c) == 2
+        assert new_c['one'] == c['one']
+        assert new_c['two'] == c['two']
+    
+    
+    def test_delitem(self):
+        c, cc = TestChainMap.simple_cm()
+    
+        with self.assertRaises(KeyError):
+            del cc['two']
+    
+        del cc['one']
+        assert len(cc) == 2
+        assert cc['one'] == 1
+        assert cc['two'] == 2
+    
+    
+    def test_popitem(self):
+        c, cc = TestChainMap.simple_cm()
+    
+        assert cc.popitem() == ('one', 'one')
+    
+        with self.assertRaises(KeyError):
+            cc.popitem()
+    
+    
+    def test_pop(self):
+        c, cc = TestChainMap.simple_cm()
+    
+        assert cc.pop('one') == 'one'
+    
+        with self.assertRaises(KeyError):
+            cc.pop('two')
+    
+        assert len(cc) == 2
+    
+    
+    def test_clear(self):
+        c, cc = TestChainMap.simple_cm()
+    
+        cc.clear()
+        assert len(cc) == 2
+        assert cc['one'] == 1
+        assert cc['two'] == 2
+    
+    
+    def test_missing(self):
+    
+        c, cc = TestChainMap.simple_cm()
+    
+        with self.assertRaises(KeyError):
+            cc['clown']
+
+
+if __name__ == '__main__':
+    unittest.main()

tests/test_future/test_standard_library.py

@@ -247,6 +247,13 @@ def test_itertools_zip_longest(self):
         self.assertEqual(list(zip_longest(a, b)),
                          [(1, 2), (2, 4), (None, 6)])
 
+    def test_ChainMap(self):
+        """
+        Tests whether collections.ChainMap is available.
+        """
+        from collections import ChainMap
+        cm = ChainMap()
+
     @unittest.expectedFailure
     @unittest.skipIf(utils.PY3, 'generic import tests are for Py2 only')
     def test_import_failure_from_module(self):