fix, add more tests [skip cirrus]

Author: mattip

numpy/lib/_npyio_impl.py

@@ -286,25 +286,25 @@ def get(self, key, default=None, /):
         """
         D.get(k,[,d]) returns D[k] if k in D, else d.  d defaults to None.
         """
-        return dict.get(self, key, default)
+        return Mapping.get(self, key, default)
 
     def items(self):
         """
         D.items() returns a set-like object providing a view on the items
         """
-        return dict.items(self)
+        return Mapping.items(self)
 
     def keys(self):
         """
         D.keys() returns a set-like object providing a view on the keys
         """
-        return dict.keys(self)
+        return Mapping.keys(self)
 
     def values(self):
         """
         D.values() returns a set-like object providing a view on the values
         """
-        return dict.values(self)
+        return Mapping.values(self)
 
 
 @set_module('numpy')

numpy/lib/tests/test_io.py

@@ -2760,12 +2760,16 @@ def test_npzfile_dict():
         assert_(f in ['x', 'y'])
         assert_equal(a.shape, (3, 3))
 
+    for a in z.values():
+        assert_equal(a.shape, (3, 3))
+
     assert_(len(z.items()) == 2)
 
     for f in z:
         assert_(f in ['x', 'y'])
 
     assert_('x' in z.keys())
+    assert (z.get('x') == z['x']).all()
 
 
 @pytest.mark.skipif(not HAS_REFCOUNT, reason="Python lacks refcounts")