Meta test for promote_dtype

Author: honno

array_api_tests/meta_tests/test_array_helpers.py

@@ -1,33 +1,51 @@
-from ..array_helpers import exactly_equal, notequal, int_to_dtype
-from ..hypothesis_helpers import integer_dtypes
-from ..dtype_helpers import dtype_nbits, dtype_signed
-from .._array_module import asarray, nan, equal, all
-
+import pytest
 from hypothesis import given, assume
 from hypothesis.strategies import integers
 
+from ..array_helpers import exactly_equal, notequal, int_to_dtype, promote_dtypes
+from ..hypothesis_helpers import integer_dtypes
+from ..dtype_helpers import dtype_nbits, dtype_signed
+from .. import _array_module as xp
+
 # TODO: These meta-tests currently only work with NumPy
 
 def test_exactly_equal():
-    a = asarray([0, 0., -0., -0., nan, nan, 1, 1])
-    b = asarray([0, -1, -0.,  0., nan,      1, 1, 2])
+    a = xp.asarray([0, 0., -0., -0., xp.nan, xp.nan, 1, 1])
+    b = xp.asarray([0, -1, -0.,  0., xp.nan,      1, 1, 2])
 
-    res = asarray([True, False, True, False, True, False, True, False])
-    assert all(equal(exactly_equal(a, b), res))
+    res = xp.asarray([True, False, True, False, True, False, True, False])
+    assert xp.all(xp.equal(exactly_equal(a, b), res))
 
 def test_notequal():
-    a = asarray([0, 0., -0., -0., nan, nan, 1, 1])
-    b = asarray([0, -1, -0.,  0., nan,      1, 1, 2])
+    a = xp.asarray([0, 0., -0., -0., xp.nan, xp.nan, 1, 1])
+    b = xp.asarray([0, -1, -0.,  0., xp.nan,      1, 1, 2])
 
-    res = asarray([False, True, False, False, False, True, False, True])
-    assert all(equal(notequal(a, b), res))
+    res = xp.asarray([False, True, False, False, False, True, False, True])
+    assert xp.all(xp.equal(notequal(a, b), res))
 
 @given(integers(), integer_dtypes)
 def test_int_to_dtype(x, dtype):
     n = dtype_nbits(dtype)
     signed = dtype_signed(dtype)
     try:
-        d = asarray(x, dtype=dtype)
+        d = xp.asarray(x, dtype=dtype)
     except OverflowError:
         assume(False)
     assert int_to_dtype(x, n, signed) == d
+
+@pytest.mark.parametrize(
+    "dtype1, dtype2, result",
+    [
+        (xp.uint8, xp.uint8, xp.uint8),
+        (xp.uint8, xp.int8, xp.int16),
+        (xp.int8, xp.int8, xp.int8),
+    ]
+)
+def test_promote_dtypes(dtype1, dtype2, result):
+    assert promote_dtypes(dtype1, dtype2) == result
+
+
+@pytest.mark.parametrize("dtype1, dtype2", [(xp.uint8, xp.float32)])
+def test_promote_dtypes_incompatible_dtypes_fail(dtype1, dtype2):
+    with pytest.raises(ValueError):
+        promote_dtypes(dtype1, dtype2)