Fix pytorch trace tests

Author: merajhashemi

tensornetwork/backends/pytorch/pytorch_backend_test.py

@@ -621,16 +621,12 @@ def test_trace(dtype, offset, axis1, axis2):
   shape = (5, 5, 5, 5)
   backend = pytorch_backend.PyTorchBackend()
   array = backend.randn(shape, dtype=dtype, seed=10)
-  if offset != 0:
-    with pytest.raises(NotImplementedError):
-      actual = backend.trace(array, offset=offset, axis1=axis1, axis2=axis2)
-
-  elif axis1 == axis2:
-    with pytest.raises(ValueError):
+  if axis1 == axis2:
+    with pytest.raises(RuntimeError):
       actual = backend.trace(array, offset=offset, axis1=axis1, axis2=axis2)
   else:
     actual = backend.trace(array, offset=offset, axis1=axis1, axis2=axis2)
-    expected = np.trace(array, axis1=axis1, axis2=axis2)
+    expected = np.trace(array, offset=offset, axis1=axis1, axis2=axis2)
     np.testing.assert_allclose(actual, expected, atol=1e-6, rtol=1e-6)