Fix test_nan_propagation for immutable arrays.

array_api_tests/test_special_cases.py

@@ -23,8 +23,9 @@
 from warnings import warn
 
 import pytest
-from hypothesis import given, note, settings
+from hypothesis import given, note, settings, assume
 from hypothesis import strategies as st
+from hypothesis.strategies import composite
 
 from array_api_tests.typing import Array, DataType
 
@@ -1321,6 +1322,11 @@ def test_empty_arrays(func_name, expected):  # TODO: parse docstrings to get exp
     else:
         assert out == expected, msg
 
+@composite
+def not_all_false(draw, shape):
+    ret = draw(hh.arrays(dtype=hh.bool_dtype, shape=shape))
+    assume(ret.any())
+    return ret
 
 @pytest.mark.parametrize(
     "func_name", [f.__name__ for f in category_to_funcs["statistical"]]
@@ -1331,10 +1337,8 @@ def test_empty_arrays(func_name, expected):  # TODO: parse docstrings to get exp
 )
 def test_nan_propagation(func_name, x, data):
     func = getattr(xp, func_name)
-    set_idx = data.draw(
-        xps.indices(x.shape, max_dims=0, allow_ellipsis=False), label="set idx"
-    )
-    x[set_idx] = float("nan")
+    nan_positions = data.draw(not_all_false(x.shape))
+    x = xp.where(nan_positions, float("nan"), x)
     note(f"{x=}")
 
     out = func(x)