BUG: fix AttributeError on accessing object in nested MaskedArray. (#15949)

* BUG: fix AttributeError on accessing object in nested MaskedArray
Co-authored-by: Rena Xu <renaxu@Renas-MacBook-Pro.local>
Co-authored-by: Eric Wieser <wieser.eric@gmail.com>
Co-authored-by: vagrant <vagrant@vagrant.vm>

1 files changed, 22 insertions, 0 deletions

diff --git a/numpy/ma/tests/test_extras.py b/numpy/ma/tests/test_extras.py
index 1c8610625..d237829cb 100644
--- a/numpy/ma/tests/test_extras.py
+++ b/numpy/ma/tests/test_extras.py
@@ -64,6 +64,28 @@ class TestGeneric:
         control = array([[(1, (1, 1))]], mask=[[(1, (1, 1))]], dtype=dt)
         assert_equal(test, control)
 
+    def test_masked_all_with_object_nested(self):
+        # Test masked_all works with nested array with dtype of an 'object'
+        # refers to issue #15895
+        my_dtype = np.dtype([('b', ([('c', object)], (1,)))])
+        masked_arr = np.ma.masked_all((1,), my_dtype)
+
+        assert_equal(type(masked_arr['b']), np.ma.core.MaskedArray)
+        assert_equal(type(masked_arr['b']['c']), np.ma.core.MaskedArray)
+        assert_equal(len(masked_arr['b']['c']), 1)
+        assert_equal(masked_arr['b']['c'].shape, (1, 1))
+        assert_equal(masked_arr['b']['c']._fill_value.shape, ())
+    
+    def test_masked_all_with_object(self):
+        # same as above except that the array is not nested
+        my_dtype = np.dtype([('b', (object, (1,)))])
+        masked_arr = np.ma.masked_all((1,), my_dtype)
+
+        assert_equal(type(masked_arr['b']), np.ma.core.MaskedArray)
+        assert_equal(len(masked_arr['b']), 1)
+        assert_equal(masked_arr['b'].shape, (1, 1))
+        assert_equal(masked_arr['b']._fill_value.shape, ())
+
     def test_masked_all_like(self):
         # Tests masked_all
         # Standard dtype