gtest: add scatter, gather and all to all unit tests

test/test_Gather.hpp

@@ -0,0 +1,25 @@
+/*************************************************************************
+ * Copyright (c) 2019-2020 Advanced Micro Devices, Inc. All rights reserved.
+ *
+ * See LICENSE.txt for license information
+ ************************************************************************/
+#ifndef TEST_GATHER_HPP
+#define TEST_GATHER_HPP
+
+#include "CorrectnessTest.hpp"
+
+namespace CorrectnessTests
+{
+    class GatherCorrectnessTest : public CorrectnessTest
+    {
+    public:
+        static void ComputeExpectedResults(Dataset& dataset, int const root)
+        {
+            for (int i = 0; i < dataset.numDevices; i++)
+                HIP_CALL(hipMemcpy((int8_t *)dataset.expected[root]+dataset.NumBytes()*i, dataset.inputs[i],
+                                   dataset.NumBytes(), hipMemcpyDeviceToHost));
+        }
+    };
+}
+
+#endif