Add a bunch of tests for extended dict.update() where the argument is

a non-dictionary mapping object.  Include tests for several expected
failure modes.

Lib/test/test_types.py

@@ -239,13 +239,83 @@ d['a'] = 4
 if d['c'] != 3 or d['a'] != 4: raise TestFailed, 'dict item assignment'
 del d['b']
 if d != {'a': 4, 'c': 3}: raise TestFailed, 'dict item deletion'
+# dict.clear()
 d = {1:1, 2:2, 3:3}
 d.clear()
 if d != {}: raise TestFailed, 'dict clear'
+# dict.update()
 d.update({1:100})
 d.update({2:20})
 d.update({1:1, 2:2, 3:3})
 if d != {1:1, 2:2, 3:3}: raise TestFailed, 'dict update'
+d.clear()
+try: d.update(None)
+except AttributeError: pass
+else: raise TestFailed, 'dict.update(None), AttributeError expected'
+class SimpleUserDict:
+    def __init__(self):
+        self.d = {1:1, 2:2, 3:3}
+    def keys(self):
+        return self.d.keys()
+    def __getitem__(self, i):
+        return self.d[i]
+d.update(SimpleUserDict())
+if d != {1:1, 2:2, 3:3}: raise TestFailed, 'dict.update(instance)'
+d.clear()
+class FailingUserDict:
+    def keys(self):
+        raise ValueError
+try: d.update(FailingUserDict())
+except ValueError: pass
+else: raise TestFailed, 'dict.keys() expected ValueError'
+class FailingUserDict:
+    def keys(self):
+        class BogonIter:
+            def __iter__(self):
+                raise ValueError
+        return BogonIter()
+try: d.update(FailingUserDict())
+except ValueError: pass
+else: raise TestFailed, 'iter(dict.keys()) expected ValueError'
+class FailingUserDict:
+    def keys(self):
+        class BogonIter:
+            def __init__(self):
+                self.i = 1
+            def __iter__(self):
+                return self
+            def next(self):
+                if self.i:
+                    self.i = 0
+                    return 'a'
+                raise ValueError
+        return BogonIter()
+    def __getitem__(self, key):
+        return key
+try: d.update(FailingUserDict())
+except ValueError: pass
+else: raise TestFailed, 'iter(dict.keys()).next() expected ValueError'
+class FailingUserDict:
+    def keys(self):
+        class BogonIter:
+            def __init__(self):
+                self.i = ord('a')
+            def __iter__(self):
+                return self
+            def next(self):
+                if self.i <= ord('z'):
+                    rtn = chr(self.i)
+                    self.i += 1
+                    return rtn
+                raise StopIteration
+        return BogonIter()
+    def __getitem__(self, key):
+        raise ValueError
+try: d.update(FailingUserDict())
+except ValueError: pass
+else: raise TestFailed, 'dict.update(), __getitem__ expected ValueError'
+# dict.copy()
+d = {1:1, 2:2, 3:3}
 if d.copy() != {1:1, 2:2, 3:3}: raise TestFailed, 'dict copy'
 if {}.copy() != {}: raise TestFailed, 'empty dict copy'
 # dict.get()