Merge pull request #20883 from honno/xp-can-cast

BUG: Fix `np.array_api.can_cast()` by not relying on `np.can_cast()`

2 files changed, 46 insertions, 0 deletions

diff --git a/numpy/array_api/tests/test_data_type_functions.py b/numpy/array_api/tests/test_data_type_functions.py
new file mode 100644
index 000000000..efe3d0abd
--- /dev/null
+++ b/numpy/array_api/tests/test_data_type_functions.py
@@ -0,0 +1,19 @@
+import pytest
+
+from numpy import array_api as xp
+
+
+@pytest.mark.parametrize(
+    "from_, to, expected",
+    [
+        (xp.int8, xp.int16, True),
+        (xp.int16, xp.int8, False),
+        (xp.bool, xp.int8, False),
+        (xp.asarray(0, dtype=xp.uint8), xp.int8, False),
+    ],
+)
+def test_can_cast(from_, to, expected):
+    """
+    can_cast() returns correct result
+    """
+    assert xp.can_cast(from_, to) == expected
diff --git a/numpy/array_api/tests/test_validation.py b/numpy/array_api/tests/test_validation.py
new file mode 100644
index 000000000..0dd100d15
--- /dev/null
+++ b/numpy/array_api/tests/test_validation.py
@@ -0,0 +1,27 @@
+from typing import Callable
+
+import pytest
+
+from numpy import array_api as xp
+
+
+def p(func: Callable, *args, **kwargs):
+    f_sig = ", ".join(
+        [str(a) for a in args] + [f"{k}={v}" for k, v in kwargs.items()]
+    )
+    id_ = f"{func.__name__}({f_sig})"
+    return pytest.param(func, args, kwargs, id=id_)
+
+
+@pytest.mark.parametrize(
+    "func, args, kwargs",
+    [
+        p(xp.can_cast, 42, xp.int8),
+        p(xp.can_cast, xp.int8, 42),
+        p(xp.result_type, 42),
+    ],
+)
+def test_raises_on_invalid_types(func, args, kwargs):
+    """Function raises TypeError when passed invalidly-typed inputs"""
+    with pytest.raises(TypeError):
+        func(*args, **kwargs)