[BUG] Skip WholeGraph Tests if GPU PyTorch Unavailable (#4820)

Skips WholeGraph tests if GPU PyTorch is not available.  Required to get tests passing on ARM.  In the future, we should move all WholeGraph-dependent code, as well as the bulk sampling API, into `cugraph-gnn` so these errors do not continue.

Authors:
  - Alex Barghi (https://github.com/alexbarghi-nv)
  - James Lamb (https://github.com/jameslamb)

Approvers:
  - James Lamb (https://github.com/jameslamb)
  - Don Acosta (https://github.com/acostadon)
  - Rick Ratzel (https://github.com/rlratzel)

URL: #4820

python/cugraph/cugraph/tests/data_store/test_gnn_feat_storage_wholegraph.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2023-2024, NVIDIA CORPORATION.
+# Copyright (c) 2023-2025, NVIDIA CORPORATION.
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
@@ -32,6 +32,20 @@ def get_cudart_version():
     return major * 1000 + minor * 10
 
 
+pytestmark = [
+    pytest.mark.skipif(
+        isinstance(torch, MissingModule) or not torch.cuda.is_available(),
+        reason="PyTorch with GPU support not available",
+    ),
+    pytest.mark.skipif(
+        isinstance(pylibwholegraph, MissingModule), reason="wholegraph not available"
+    ),
+    pytest.mark.skipif(
+        get_cudart_version() < 11080, reason="not compatible with CUDA < 11.8"
+    ),
+]
+
+
 def runtest(rank: int, world_size: int):
     torch.cuda.set_device(rank)
 
@@ -69,13 +83,6 @@ def runtest(rank: int, world_size: int):
 
 
 @pytest.mark.sg
-@pytest.mark.skipif(isinstance(torch, MissingModule), reason="torch not available")
-@pytest.mark.skipif(
-    isinstance(pylibwholegraph, MissingModule), reason="wholegraph not available"
-)
-@pytest.mark.skipif(
-    get_cudart_version() < 11080, reason="not compatible with CUDA < 11.8"
-)
 def test_feature_storage_wholegraph_backend():
     world_size = torch.cuda.device_count()
     print("gpu count:", world_size)
@@ -87,13 +94,6 @@ def test_feature_storage_wholegraph_backend():
 
 
 @pytest.mark.mg
-@pytest.mark.skipif(isinstance(torch, MissingModule), reason="torch not available")
-@pytest.mark.skipif(
-    isinstance(pylibwholegraph, MissingModule), reason="wholegraph not available"
-)
-@pytest.mark.skipif(
-    get_cudart_version() < 11080, reason="not compatible with CUDA < 11.8"
-)
 def test_feature_storage_wholegraph_backend_mg():
     world_size = torch.cuda.device_count()
     print("gpu count:", world_size)