[Feature] use pytest for sgl-kernel (#4896)

sgl-kernel/tests/speculative/test_eagle_utils.py

@@ -1,3 +1,4 @@
+import pytest
 import torch
 import torch.nn.functional as F
 from sgl_kernel import verify_tree_greedy
@@ -85,14 +86,14 @@ def test_verify_tree_greedy():
     print(f"{accept_index=}")
     print(f"{accept_token_num=}")
 
-    return predicts, accept_index, accept_token_num
-
-
-if __name__ == "__main__":
-    predicts, accept_index, accept_token_num = test_verify_tree_greedy()
+    # Check the expected output.
     assert predicts.tolist() == [3, -1, -1, 4, 5, 18, 11, -1, -1, -1, 12, 18]
     assert accept_index.tolist() == [
         [0, 3, 4, 5],
         [6, 10, 11, -1],
     ]
     assert accept_token_num.tolist() == [3, 2]
+
+
+if __name__ == "__main__":
+    pytest.main([__file__])