Add more dlpack tests (#1670)

* Fixture all_root_devices is to keep only 2 devices from each platform

This is done to speed-up test suite execution on multi-GPU system,
like Aurora.

* Add tests for legacy/versions capsule import-export

* Expand tests more to improve coverage

Use F-contiguous array to both legacy and versioned capsule.
Add tests for read-only array and for use of copy=True keyword
for __dlpack__ call

Author: oleksandr-pavlyk

dpctl/tests/test_usm_ndarray_dlpack.py

@@ -14,13 +14,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import collections
 import ctypes
 
 import pytest
 from helper import skip_if_dtype_not_supported
 
 import dpctl
 import dpctl.tensor as dpt
+import dpctl.tensor._dlpack as _dlp
 
 device_oneAPI = 14  # DLDeviceType.kDLOneAPI
 
@@ -57,7 +59,18 @@ def typestr(request):
 
 @pytest.fixture
 def all_root_devices():
-    return dpctl.get_devices()
+    """
+    Caches root devices. For the sake of speed
+    of test suite execution, keep at most two
+    devices from each platform
+    """
+    devs = dpctl.get_devices()
+    devs_per_platform = collections.defaultdict(list)
+    for dev in devs:
+        devs_per_platform[dev.sycl_platform].append(dev)
+
+    pruned = map(lambda li: li[:2], devs_per_platform.values())
+    return sum(pruned, start=[])
 
 
 def test_dlpack_device(usm_type, all_root_devices):
@@ -216,9 +229,8 @@ def test_dlpack_from_subdevice():
     except dpctl.SyclSubDeviceCreationError:
         sdevs = None
     try:
-        sdevs = (
-            dev.create_sub_devices(partition=[1, 1]) if sdevs is None else sdevs
-        )
+        if sdevs is None:
+            sdevs = dev.create_sub_devices(partition=[1, 1])
     except dpctl.SyclSubDeviceCreationError:
         pytest.skip("Default device can not be partitioned")
     assert isinstance(sdevs, list) and len(sdevs) > 0
@@ -234,3 +246,76 @@ def test_dlpack_from_subdevice():
     ar = dpt.arange(n, dtype=dpt.int32, sycl_queue=q)
     ar2 = dpt.from_dlpack(ar)
     assert ar2.sycl_device == sdevs[0]
+
+
+def test_legacy_dlpack_capsule():
+    try:
+        x = dpt.arange(100, dtype="i4")
+    except dpctl.SyclDeviceCreationError:
+        pytest.skip("No default device available")
+
+    legacy_ver = (0, 8)
+
+    cap = x.__dlpack__(max_version=legacy_ver)
+    y = _dlp.from_dlpack_capsule(cap)
+    del cap
+    assert x._pointer == y._pointer
+
+    x2 = dpt.reshape(x, (10, 10)).mT
+    cap = x2.__dlpack__(max_version=legacy_ver)
+    y = _dlp.from_dlpack_capsule(cap)
+    del cap
+    assert x2._pointer == y._pointer
+    del x2
+
+    x2 = dpt.asarray(dpt.reshape(x, (10, 10)), order="F")
+    cap = x2.__dlpack__(max_version=legacy_ver)
+    y = _dlp.from_dlpack_capsule(cap)
+    del cap
+    assert x2._pointer == y._pointer
+
+    x3 = x[::-2]
+    cap = x3.__dlpack__(max_version=legacy_ver)
+    y = _dlp.from_dlpack_capsule(cap)
+    assert x3._pointer == y._pointer
+    del x3, y, x
+    del cap
+
+
+def test_versioned_dlpack_capsule():
+    try:
+        x = dpt.arange(100, dtype="i4")
+    except dpctl.SyclDeviceCreationError:
+        pytest.skip("No default device available")
+
+    max_supported_ver = _dlp.get_build_dlpack_version()
+    cap = x.__dlpack__(max_version=max_supported_ver)
+    y = _dlp.from_dlpack_versioned_capsule(cap)
+    del cap
+    assert x._pointer == y._pointer
+
+    x2 = dpt.asarray(dpt.reshape(x, (10, 10)), order="F")
+    cap = x2.__dlpack__(max_version=max_supported_ver)
+    y = _dlp.from_dlpack_versioned_capsule(cap)
+    del cap
+    assert x2._pointer == y._pointer
+    del x2
+
+    x3 = x[::-2]
+    cap = x3.__dlpack__(max_version=max_supported_ver)
+    y = _dlp.from_dlpack_versioned_capsule(cap)
+    assert x3._pointer == y._pointer
+    del x3, y, x
+    del cap
+
+    # read-only array
+    x = dpt.arange(100, dtype="i4")
+    x.flags["W"] = False
+    cap = x.__dlpack__(max_version=max_supported_ver)
+    y = _dlp.from_dlpack_versioned_capsule(cap)
+    assert x._pointer == y._pointer
+
+    # read-only array, and copy
+    cap = x.__dlpack__(max_version=max_supported_ver, copy=True)
+    y = _dlp.from_dlpack_versioned_capsule(cap)
+    assert x._pointer != y._pointer