Add test for permute.

grassmann_tensor/tensor.py

@@ -115,6 +115,7 @@ def permute(self, before_by_after: tuple[int, ...]) -> GrassmannTensor:
         """
         Permute the indices of the Grassmann tensor.
         """
+        assert len(before_by_after) == len(set(before_by_after)), "Permutation indices must be unique."
         assert set(before_by_after) == set(range(self.tensor.dim())), "Permutation indices must cover all dimensions."
 
         arrow = tuple(self.arrow[i] for i in before_by_after)

tests/permute_test.py

@@ -0,0 +1,35 @@
+import pytest
+import torch
+from grassmann_tensor import GrassmannTensor
+
+PermuteCase = tuple[tuple[bool, ...], tuple[tuple[int, int], ...], torch.Tensor, tuple[int, ...], torch.Tensor]
+
+
+@pytest.mark.parametrize("x", [
+    ((False, False), ((1, 1), (1, 1)), torch.tensor([[1, 0], [0, 4]]), (0, 1), torch.tensor([[1, 0], [0, 4]])),
+    ((True, False), ((1, 1), (1, 1)), torch.tensor([[1, 0], [0, 4]]), (1, 0), torch.tensor([[1, 0], [0, -4]])),
+    ((False, True, True), ((1, 1), (1, 1), (1, 1)), torch.tensor([[[1, 0], [0, 2]], [[0, 3], [4, 0]]]), (0, 2, 1), torch.tensor([[[1, 0], [0, -2]], [[0, 4], [3, 0]]])),
+    ((True, True, True), ((1, 1), (1, 1), (1, 1)), torch.tensor([[[1, 0], [0, 2]], [[0, 3], [4, 0]]]), (1, 0, 2), torch.tensor([[[1, 0], [0, 3]], [[0, 2], [-4, 0]]])),
+    ((True, False, False), ((1, 1), (1, 1), (1, 1)), torch.tensor([[[1, 0], [0, 2]], [[0, 3], [4, 0]]]), (2, 1, 0), torch.tensor([[[1, 0], [0, -4]], [[0, -3], [-2, 0]]])),
+    ((False, False, False), ((1, 1), (1, 1), (1, 1)), torch.tensor([[[1, 0], [0, 2]], [[0, 3], [4, 0]]]), (2, 0, 1), torch.tensor([[[1, 0], [0, 4]], [[0, -2], [-3, 0]]])),
+])
+def test_permute(x: PermuteCase) -> None:
+    arrow, edges, tensor, before_by_after, expected = x
+    grassmann_tensor = GrassmannTensor(arrow, edges, tensor)
+    result = grassmann_tensor.permute(before_by_after)
+    assert torch.allclose(result.tensor, expected)
+
+
+PermuteFailCase = tuple[tuple[bool, ...], tuple[tuple[int, int], ...], torch.Tensor, tuple[int, ...]]
+
+
+@pytest.mark.parametrize("x", [
+    ((False, False), ((1, 1), (1, 1)), torch.tensor([[1, 0], [0, 4]]), (0, 0)),
+    ((False, False), ((1, 1), (1, 1)), torch.tensor([[1, 0], [0, 4]]), (2, 0)),
+    ((False, False), ((1, 1), (1, 1)), torch.tensor([[1, 0], [0, 4]]), (0, 0, 1)),
+])
+def test_permute_fail(x: PermuteFailCase) -> None:
+    arrow, edges, tensor, before_by_after = x
+    grassmann_tensor = GrassmannTensor(arrow, edges, tensor)
+    with pytest.raises(AssertionError):
+        grassmann_tensor.permute(before_by_after)