Added a test for shuffling

unsupported/Eigen/CXX11/src/Tensor/TensorShuffling.h

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorShuffling.h b/unsupported/Eigen/CXX11/src/Tensor/TensorShuffling.h
index c455300..15a22aa 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorShuffling.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorShuffling.h
@@ -67,7 +67,7 @@
       : m_xpr(expr), m_shuffle(shuffle) {}
 
     EIGEN_DEVICE_FUNC
-    const Shuffle& shuffle() const { return m_shuffle; }
+    const Shuffle& shufflePermutation() const { return m_shuffle; }
 
     EIGEN_DEVICE_FUNC
     const typename internal::remove_all<typename XprType::Nested>::type&
@@ -119,7 +119,7 @@
       : m_impl(op.expression(), device)
   {
     const typename TensorEvaluator<ArgType, Device>::Dimensions& input_dims = m_impl.dimensions();
-    const Shuffle& shuffle = op.shuffle();
+    const Shuffle& shuffle = op.shufflePermutation();
     for (int i = 0; i < NumDims; ++i) {
       m_dimensions[i] = input_dims[shuffle[i]];
     }

unsupported/test/cxx11_tensor_shuffling.cpp

diff --git a/unsupported/test/cxx11_tensor_shuffling.cpp b/unsupported/test/cxx11_tensor_shuffling.cpp
index 2f7fd9e..d11444a 100644
--- a/unsupported/test/cxx11_tensor_shuffling.cpp
+++ b/unsupported/test/cxx11_tensor_shuffling.cpp
@@ -176,12 +176,53 @@
   }
 }
 
+
+template <int DataLayout>
+static void test_shuffle_unshuffle()
+{
+  Tensor<float, 4, DataLayout> tensor(2,3,5,7);
+  tensor.setRandom();
+
+  // Choose a random permutation.
+  array<ptrdiff_t, 4> shuffles;
+  for (int i = 0; i < 4; ++i) {
+    shuffles[i] = i;
+  }
+  array<ptrdiff_t, 4> shuffles_inverse;
+  for (int i = 0; i < 4; ++i) {
+    const ptrdiff_t index = internal::random<ptrdiff_t>(i, 3);
+    shuffles_inverse[shuffles[index]] = i;
+    std::swap(shuffles[i], shuffles[index]);
+  }
+
+  Tensor<float, 4, DataLayout> shuffle;
+  shuffle = tensor.shuffle(shuffles).shuffle(shuffles_inverse);
+
+  VERIFY_IS_EQUAL(shuffle.dimension(0), 2);
+  VERIFY_IS_EQUAL(shuffle.dimension(1), 3);
+  VERIFY_IS_EQUAL(shuffle.dimension(2), 5);
+  VERIFY_IS_EQUAL(shuffle.dimension(3), 7);
+
+  for (int i = 0; i < 2; ++i) {
+    for (int j = 0; j < 3; ++j) {
+      for (int k = 0; k < 5; ++k) {
+        for (int l = 0; l < 7; ++l) {
+          VERIFY_IS_EQUAL(tensor(i,j,k,l), shuffle(i,j,k,l));
+        }
+      }
+    }
+  }
+}
+
+
 void test_cxx11_tensor_shuffling()
 {
-   CALL_SUBTEST(test_simple_shuffling<ColMajor>());
-   CALL_SUBTEST(test_simple_shuffling<RowMajor>());
-   CALL_SUBTEST(test_expr_shuffling<ColMajor>());
-   CALL_SUBTEST(test_expr_shuffling<RowMajor>());
-   CALL_SUBTEST(test_shuffling_as_value<ColMajor>());
-   CALL_SUBTEST(test_shuffling_as_value<RowMajor>());
+  CALL_SUBTEST(test_simple_shuffling<ColMajor>());
+  CALL_SUBTEST(test_simple_shuffling<RowMajor>());
+  CALL_SUBTEST(test_expr_shuffling<ColMajor>());
+  CALL_SUBTEST(test_expr_shuffling<RowMajor>());
+  CALL_SUBTEST(test_shuffling_as_value<ColMajor>());
+  CALL_SUBTEST(test_shuffling_as_value<RowMajor>());
+  CALL_SUBTEST(test_shuffle_unshuffle<ColMajor>());
+  CALL_SUBTEST(test_shuffle_unshuffle<RowMajor>());
 }