Update test_collections.py to include test_issue584().

Added testing for | and |= operators for ChainMap objects.

Author: curtisbucher

Lib/test/test_collections.py

@@ -232,6 +232,30 @@ def __contains__(self, key):
         for k, v in dict(a=1, B=20, C=30, z=100).items():             # check get
             self.assertEqual(d.get(k, 100), v)
 
+    def test_issue584(self):
+        'Tests for changes in issue584 dealing with | and |= operators'
+        a = ChainMap(dict(a=1, b=2), dict(c=3, d=4))
+        b = ChainMap(dict(a=10, e=5), dict(b=20, d=4))
+        c = dict(a = 10, c = 30)
+
+        ## Testing | operator between chainmaps
+        d = a | b
+        self.assertEqual(d, ChainMap(a.maps[0] | dict(b), *a.maps[1:]))
+
+        ## Testing |= operator between chainmaps
+        a |= b
+        self.assertEqual(d, a)
+
+        ## Testing | operator between chainmap and mapping, and vice versa
+        e = b | c
+        self.assertEqual(e, ChainMap(e.maps[0] | c, *b.maps[1:]))
+
+        f = c | b
+        self.assertEqual(f, ChainMap(c | dict(b)))
+
+        ## Testing |= operator between chainmap and mapping 
+        b |= c
+        self.assertEqual(e,b)
 
 ################################################################################
 ### Named Tuples