Misc updates regarding Windows and unittests (#586)

* SKIP bbox test without CUDA

* use full filepath for creating latest.pth

mmcv/runner/epoch_based_runner.py

@@ -169,7 +169,7 @@ class EpochBasedRunner(BaseRunner):
             if platform.system() != 'Windows':
                 mmcv.symlink(filename, dst_file)
             else:
-                shutil.copy(filename, dst_file)
+                shutil.copy(filepath, dst_file)
 
 
 @RUNNERS.register_module()

tests/test_ops/test_bbox.py

 import numpy as np
+import pytest
 import torch
 
 
+@pytest.mark.skipif(
+    not torch.cuda.is_available(), reason='requires CUDA support')
 class TestBBox(object):
 
     def _test_bbox_overlaps(self, dtype=torch.float):
 
-        if not torch.cuda.is_available():
-            return
         from mmcv.ops import bbox_overlaps
         b1 = torch.tensor([[1.0, 1.0, 3.0, 4.0], [2.0, 2.0, 3.0, 4.0],
                            [7.0, 7.0, 8.0, 8.0]]).cuda().type(dtype)