Revert "WIP: remove test_torch.py"

This reverts commit a7f56b9.

Author: ev-br

tests/test_torch.py

@@ -0,0 +1,74 @@
+"""Test "unspecified" behavior which we cannot easily test in the Array API test suite.
+"""
+import itertools
+
+import pytest
+import torch
+
+from array_api_compat import torch as xp
+
+
+class TestResultType:
+    def test_empty(self):
+        with pytest.raises(ValueError):
+            xp.result_type()
+
+    def test_one_arg(self):
+        for x in [1, 1.0, 1j, '...', None]:
+            with pytest.raises((ValueError, AttributeError)):
+                xp.result_type(x)
+
+        for x in [xp.float32, xp.int64, torch.complex64]:
+            assert xp.result_type(x) == x
+
+        for x in [xp.asarray(True, dtype=xp.bool), xp.asarray(1, dtype=xp.complex64)]:
+            assert xp.result_type(x) == x.dtype
+
+    def test_two_args(self):
+        # Only include here things "unspecified" in the spec
+
+        # scalar, tensor or tensor,tensor
+        for x, y in [
+            (1., 1j),
+            (1j, xp.arange(3)),
+            (True, xp.asarray(3.)),
+            (xp.ones(3) == 1, 1j*xp.ones(3)),
+        ]:
+            assert xp.result_type(x, y) == torch.result_type(x, y)
+
+        # dtype, scalar
+        for x, y in [
+            (1j, xp.int64),
+            (True, xp.float64),
+        ]:
+            assert xp.result_type(x, y) == torch.result_type(x, xp.empty([], dtype=y))
+
+        # dtype, dtype
+        for x, y in [
+            (xp.bool, xp.complex64)
+        ]:
+            xt, yt = xp.empty([], dtype=x), xp.empty([], dtype=y)
+            assert xp.result_type(x, y) == torch.result_type(xt, yt)
+
+    def test_multi_arg(self):
+        torch.set_default_dtype(torch.float32)
+
+        args = [1., 5, 3, torch.asarray([3], dtype=torch.float16), 5, 6, 1.]
+        assert xp.result_type(*args) == torch.float16
+
+        args = [1, 2, 3j, xp.arange(3, dtype=xp.float32), 4, 5, 6]
+        assert xp.result_type(*args) == xp.complex64
+
+        args = [1, 2, 3j, xp.float64, 4, 5, 6]
+        assert xp.result_type(*args) == xp.complex128
+
+        args = [1, 2, 3j, xp.float64, 4, xp.asarray(3, dtype=xp.int16), 5, 6, False]
+        assert xp.result_type(*args) == xp.complex128
+
+        i64 = xp.ones(1, dtype=xp.int64)
+        f16 = xp.ones(1, dtype=xp.float16)
+        for i in itertools.permutations([i64, f16, 1.0, 1.0]):
+            assert xp.result_type(*i) == xp.float16, f"{i}"
+
+        with pytest.raises(ValueError):
+            xp.result_type(1, 2, 3, 4)