Add generateRandomSeed utility to generate randomness seed

src/catch2/internal/catch_random_seed_generation.cpp

@@ -0,0 +1,34 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE_1_0.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+#include <catch2/internal/catch_random_seed_generation.hpp>
+
+#include <catch2/internal/catch_enforce.hpp>
+
+#include <ctime>
+#include <random>
+
+namespace Catch {
+
+    std::uint32_t generateRandomSeed( GenerateFrom from ) {
+        switch ( from ) {
+        case GenerateFrom::Time:
+            return static_cast<std::uint32_t>( std::time( nullptr ) );
+
+        case GenerateFrom::Default:
+        case GenerateFrom::RandomDevice:
+            // In theory, a platform could have random_device that returns just
+            // 16 bits. That is still some randomness, so we don't care too much
+            return static_cast<std::uint32_t>( std::random_device{}() );
+
+        default:
+            CATCH_ERROR("Unknown generation method");
+        }
+    }
+
+} // end namespace Catch