Add regression tests (#119)

- Add `tests/scripts/save_policy_to_safetensor.py` to generate test artifacts
- Add `test_backward_compatibility to test generated outputs from the policies against artifacts

tests/utils.py

@@ -1,3 +1,5 @@
+import platform
+
 import pytest
 import torch
 
@@ -9,6 +11,51 @@ DEFAULT_CONFIG_PATH = "lerobot/configs/default.yaml"
 DEVICE = "cuda" if torch.cuda.is_available() else "cpu"
 
 
+def require_x86_64_kernel(func):
+    """
+    Decorator that skips the test if plateform device is not an x86_64 cpu.
+    """
+    from functools import wraps
+
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        if platform.machine() != "x86_64":
+            pytest.skip("requires x86_64 plateform")
+        return func(*args, **kwargs)
+
+    return wrapper
+
+
+def require_cpu(func):
+    """
+    Decorator that skips the test if device is not cpu.
+    """
+    from functools import wraps
+
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        if DEVICE != "cpu":
+            pytest.skip("requires cpu")
+        return func(*args, **kwargs)
+
+    return wrapper
+
+
+def require_cuda(func):
+    """
+    Decorator that skips the test if cuda is not available.
+    """
+    from functools import wraps
+
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        if not torch.cuda.is_available():
+            pytest.skip("requires cuda")
+        return func(*args, **kwargs)
+
+    return wrapper
+
+
 def require_env(func):
     """
     Decorator that skips the test if the required environment package is not installed.