Implement a unit test for isSingleThreadAcc and isMultiThreadAcc

Implement a unit test for alpaka::isSingleThreadAcc<T> and alpaka::isMultiThreadAcc<T>.

Signed-off-by: Andrea Bocci <andrea.bocci@cern.ch>

test/unit/acc/src/AccTraitTest.cpp

@@ -0,0 +1,35 @@
+/* Copyright 2024 Andrea Bocci
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+#include <alpaka/acc/Traits.hpp>
+#include <alpaka/test/acc/TestAccs.hpp>
+
+#include <catch2/catch_template_test_macros.hpp>
+#include <catch2/catch_test_macros.hpp>
+
+TEMPLATE_LIST_TEST_CASE("isSingleThreadAcc", "[acc]", alpaka::test::TestAccs)
+{
+    using Acc = TestType;
+
+    // Check that both traits are defined, and that only one is true.
+    REQUIRE(alpaka::isSingleThreadAcc<Acc> != alpaka::isMultiThreadAcc<Acc>);
+
+    auto const platform = alpaka::Platform<Acc>{};
+    auto const dev = alpaka::getDevByIdx(platform, 0);
+    auto const devProps = alpaka::getAccDevProps<Acc>(dev);
+
+    // Compare the runtime properties with the compile time trait.
+    INFO("Accelerator: " << alpaka::core::demangled<Acc>);
+    if constexpr(alpaka::isSingleThreadAcc<Acc>)
+    {
+        // Require a single thread per block.
+        REQUIRE(devProps.m_blockThreadCountMax == 1);
+    }
+    else
+    {
+        // Assume multiple threads per block, but allow a single thread per block.
+        // For example, the AccCpuOmp2Threads accelerator may report a single thread on a single core system.
+        REQUIRE(devProps.m_blockThreadCountMax >= 1);
+    }
+}