chore: import upstream snapshot with attribution

tests/python/common/backend/test_set_default_backend.py

@@ -0,0 +1,12 @@
+import os
+import unittest
+
+import backend as F
+
+
+def test_set_default_backend():
+    default_dir = os.path.join(os.path.expanduser("~"), ".dgl_unit_test")
+    F.set_default_backend(default_dir, "pytorch")
+
+    # make sure the config file was created
+    assert os.path.exists(os.path.join(default_dir, "config.json"))

tests/python/common/backend/test_tensor.py

@@ -0,0 +1,54 @@
+import unittest
+
+import backend as F
+
+import dgl
+import dgl.ndarray as nd
+import numpy as np
+
+
+@unittest.skipIf(
+    dgl.backend.backend_name == "tensorflow",
+    reason="TF doesn't support inplace update",
+)
+def test_dlpack():
+    # test dlpack conversion.
+    def nd2th():
+        ans = np.array(
+            [[1.0, 1.0, 1.0, 1.0], [0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0]]
+        )
+        x = nd.array(np.zeros((3, 4), dtype=np.float32))
+        dl = x.to_dlpack()
+        y = F.zerocopy_from_dlpack(dl)
+        y[0] = 1
+        print(x)
+        print(y)
+        assert np.allclose(x.asnumpy(), ans)
+
+    def th2nd():
+        ans = np.array(
+            [[1.0, 1.0, 1.0, 1.0], [0.0, 0.0, 0.0, 0.0], [0.0, 0.0, 0.0, 0.0]]
+        )
+        x = F.zeros((3, 4))
+        dl = F.zerocopy_to_dlpack(x)
+        y = nd.from_dlpack(dl)
+        x[0] = 1
+        print(x)
+        print(y)
+        assert np.allclose(y.asnumpy(), ans)
+
+    def th2nd_incontiguous():
+        x = F.astype(F.tensor([[0, 1], [2, 3]]), F.int64)
+        ans = np.array([0, 2])
+        y = x[:2, 0]
+        # Uncomment this line and comment the one below to observe error
+        # dl = dlpack.to_dlpack(y)
+        dl = F.zerocopy_to_dlpack(y)
+        z = nd.from_dlpack(dl)
+        print(x)
+        print(z)
+        assert np.allclose(z.asnumpy(), ans)
+
+    nd2th()
+    th2nd()
+    th2nd_incontiguous()