added testing module (#435)

colossalai/testing/comparison.py

@@ -0,0 +1,29 @@
+import torch
+import torch.distributed as dist
+from torch import Tensor
+from torch.distributed import ProcessGroup
+
+
+def assert_equal(a: Tensor, b: Tensor):
+    assert torch.all(a == b), f'expected a and b to be equal but they are not, {a} vs {b}'
+
+def assert_not_equal(a: Tensor, b: Tensor):
+    assert not torch.all(a == b), f'expected a and b to be not equal but they are, {a} vs {b}'
+
+def assert_close(a: Tensor, b: Tensor, rtol: float = 1e-5, atol: float = 1e-8):
+    assert torch.allclose(a, b, rtol=rtol, atol=atol), f'expected a and b to be close but they are not, {a} vs {b}'
+
+def assert_close_loose(a: Tensor, b: Tensor, rtol: float = 1e-2, atol: float = 1e-3):
+    assert_close(a, b, rtol, atol)
+
+def assert_equal_in_group(tensor: Tensor, process_group: ProcessGroup = None):
+    # all gather tensors from different ranks
+    world_size = dist.get_world_size(process_group)
+    tensor_list = [torch.empty_like(tensor) for _ in range(world_size)]
+    dist.all_gather(tensor_list, tensor, group=process_group)
+
+    # check if they are equal one by one
+    for i in range(world_size - 1):
+        a = tensor_list[i]
+        b = tensor_list[i+1]
+        assert torch.all(a == b), f'expected tensors on rank {i} and {i+1} to be equal but they are not, {a} vs {b}'