Improving basic tests. (#6145)

tests/python/common/function/test_basics.py

-import unittest
+import warnings
 from collections import defaultdict as ddict
 
 import backend as F
@@ -6,8 +6,6 @@ import backend as F
 import dgl
 import networkx as nx
 import numpy as np
-import scipy.sparse as ssp
-from dgl import DGLGraph
 from utils import parametrize_idtype
 
 D = 5
@@ -33,7 +31,7 @@ def apply_node_func(nodes):
 
 
 def generate_graph_old(grad=False):
-    g = DGLGraph()
+    g = dgl.graph([])
     g.add_nodes(10)  # 10 nodes
     # create a graph where 0 is the source and 9 is the sink
     # 17 edges
@@ -419,7 +417,14 @@ def test_update_all_0deg(idtype):
     # test#2: graph with no edge
     g = dgl.graph(([], []), num_nodes=5, idtype=idtype, device=F.ctx())
     g.ndata["h"] = old_repr
-    g.update_all(_message, _reduce, lambda nodes: {"h": nodes.data["h"] * 2})
+    # Intercepting the warning: The input graph for the user-defined edge
+    # function does not contain valid edges.
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore", category=UserWarning)
+        g.update_all(
+            _message, _reduce, lambda nodes: {"h": nodes.data["h"] * 2}
+        )
+
     new_repr = g.ndata["h"]
     # should fallback to apply
     assert F.allclose(new_repr, 2 * old_repr)
@@ -455,7 +460,12 @@ def test_pull_0deg(idtype):
     # test#2: pull only 0deg node
     old = F.randn((2, 5))
     g.ndata["h"] = old
+    # Intercepting the warning: The input graph for the user-defined edge
+    # function does not contain valid edges
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore", category=UserWarning)
         g.pull(0, _message, _reduce, lambda nodes: {"h": nodes.data["h"] * 2})
+
     new = g.ndata["h"]
     # 0deg check: fallback to apply
     assert F.allclose(new[0], 2 * old[0])
@@ -467,8 +477,7 @@ def test_dynamic_addition():
     N = 3
     D = 1
 
-    g = DGLGraph()
-    g = g.to(F.ctx())
+    g = dgl.graph([]).to(F.ctx())
 
     # Test node addition
     g.add_nodes(N)