Fixing some unittest warnings. (#6122)

Co-authored-by: Hongzhi (Steve), Chen <chenhongzhi.nkcs@gmail.com>

python/dgl/backend/pytorch/tensor.py

@@ -509,6 +509,7 @@ def backward(x, head_gradient=None):
 
 
 def grad(x):
+    x.retain_grad()
     return x.grad
 
 

python/dgl/convert.py

@@ -1231,6 +1231,16 @@ def bipartite_from_scipy(
     return g.to(device)
 
 
+def _batcher(lst):
+    if F.is_tensor(lst[0]):
+        return F.cat([F.unsqueeze(x, 0) for x in lst], dim=0)
+
+    if isinstance(lst[0], np.ndarray):
+        return F.tensor(np.array(lst))
+
+    return F.tensor(lst)
+
+
 def from_networkx(
     nx_graph,
     node_attrs=None,
@@ -1367,12 +1377,6 @@ def from_networkx(
 
     # handle features
     # copy attributes
-    def _batcher(lst):
-        if F.is_tensor(lst[0]):
-            return F.cat([F.unsqueeze(x, 0) for x in lst], dim=0)
-        else:
-            return F.tensor(lst)
-
     if node_attrs is not None:
         # mapping from feature name to a list of tensors to be concatenated
         attr_dict = defaultdict(list)
@@ -1592,12 +1596,6 @@ def bipartite_from_networkx(
 
     # handle features
     # copy attributes
-    def _batcher(lst):
-        if F.is_tensor(lst[0]):
-            return F.cat([F.unsqueeze(x, 0) for x in lst], dim=0)
-        else:
-            return F.tensor(lst)
-
     if u_attrs is not None:
         # mapping from feature name to a list of tensors to be concatenated
         src_attr_dict = defaultdict(list)

tests/python/common/test_propagate.py

@@ -89,7 +89,7 @@ def test_prop_nodes_topo(idtype):
     assert check_fail(dgl.prop_nodes_topo, g)  # has loop
 
     # tree
-    tree = dgl.DGLGraph()
+    tree = dgl.graph([])
     tree.add_nodes(5)
     tree.add_edges(1, 0)
     tree.add_edges(2, 0)

tests/python/common/test_subgraph.py

@@ -13,7 +13,7 @@ D = 5
 
 
 def generate_graph(grad=False, add_data=True):
-    g = dgl.DGLGraph().to(F.ctx())
+    g = dgl.graph([]).to(F.ctx())
     g.add_nodes(10)
     # create a graph where 0 is the source and 9 is the sink
     for i in range(1, 9):
@@ -111,7 +111,7 @@ def test_subgraph_relabel_nodes(relabel_nodes):
 
 
 def _test_map_to_subgraph():
-    g = dgl.DGLGraph()
+    g = dgl.graph([])
     g.add_nodes(10)
     g.add_edges(F.arange(0, 9), F.arange(1, 10))
     h = g.subgraph([0, 1, 2, 5, 8])

tests/python/common/test_traversal.py

@@ -95,7 +95,7 @@ DFS_LABEL_NAMES = ["forward", "reverse", "nontree"]
 
 @parametrize_idtype
 def test_dfs_labeled_edges(idtype, example=False):
-    dgl_g = dgl.DGLGraph().astype(idtype)
+    dgl_g = dgl.graph([]).astype(idtype)
     dgl_g.add_nodes(6)
     dgl_g.add_edges([0, 1, 0, 3, 3], [1, 2, 2, 4, 5])
     dgl_edges, dgl_labels = dgl.dfs_labeled_edges_generator(