add unit test for Slice with different steps

unit_tests/operator/Test_SliceImpl.cpp

@@ -228,4 +228,52 @@ TEST_CASE("[cpu/operator] Slice(forward)", "[Slice][CPU]") {
         REQUIRE(op->getOutput(0)->dims() == expectedOutput->dims());
         REQUIRE(op->getOutput(0)->dataType() == expectedOutput->dataType());
     }
+
+    SECTION("Different Steps") {
+        std::shared_ptr<Tensor> input0 = std::make_shared<Tensor>(Array3D<int,4,2,8> {
+            {
+                {
+                    { 0, 1, 2,-3, 4,-5,-6,7},
+                    {-5, 4, 2,-3, 4,-5,-6,-7}
+                },
+                {
+                    { 10, 11, 12,-13, 14,-15,-16,17},
+                    {-15, 14, 12,-13, 14,-15,-16,-17}
+                },
+                {
+                    { 20, 21, 22,-23, 24,-25,-26,27},
+                    {-25, 24, 22,-23, 24,-25,-26,-27}
+                },
+                {
+                    { 30, 31, 32,-33, 34,-35,-36,37},
+                    {-35, 34, 32,-33, 34,-35,-36,-37}
+                }
+            }
+        });
+        std::shared_ptr<Tensor> expectedOutput = std::make_shared<Tensor>(Array3D<int,2,1,3> {
+            {
+                {
+                    { 7, 4, 1}
+                },
+                {
+                    { 27, 24, 21}
+                }
+            }
+        });
+
+        std::shared_ptr<Node> mySlice = Slice({0,0,7}, {4,1,0}, {0,1,2}, {2,1,-3});
+        // Steps are 2,1,-3 so the slice will be:
+        // on Axis 0: from 0 to 4 by step of 2
+        // on Axis 1: from 0 to 1 by step of 1
+        // on Axis 2: from 7 to 0 by step of -3 (reverse the order of elements)
+        auto op = std::static_pointer_cast<OperatorTensor>(mySlice -> getOperator());
+        mySlice->getOperator()->associateInput(0,input0);
+        mySlice->getOperator()->setDataType(DataType::Int32);
+        mySlice->getOperator()->setBackend("cpu");
+        mySlice->forward();
+        op->getOutput(0)->print();
+        REQUIRE(*(op->getOutput(0)) == *expectedOutput);
+        REQUIRE(op->getOutput(0)->dims() == expectedOutput->dims());
+        REQUIRE(op->getOutput(0)->dataType() == expectedOutput->dataType());
+    }
 }