Add generateRandomSeed utility to generate randomness seed

src/CMakeLists.txt

@@ -106,6 +106,7 @@ set(INTERNAL_HEADERS
     ${SOURCES_DIR}/internal/catch_polyfills.hpp
     ${SOURCES_DIR}/internal/catch_preprocessor.hpp
     ${SOURCES_DIR}/internal/catch_random_number_generator.hpp
+    ${SOURCES_DIR}/internal/catch_random_seed_generation.hpp
     ${SOURCES_DIR}/catch_reporter_registrars.hpp
     ${SOURCES_DIR}/internal/catch_reporter_registry.hpp
     ${SOURCES_DIR}/internal/catch_result_type.hpp
@@ -175,6 +176,7 @@ set(IMPL_SOURCES
     ${SOURCES_DIR}/catch_registry_hub.cpp
     ${SOURCES_DIR}/internal/catch_combined_tu.cpp
     ${SOURCES_DIR}/internal/catch_random_number_generator.cpp
+    ${SOURCES_DIR}/internal/catch_random_seed_generation.cpp
     ${SOURCES_DIR}/internal/catch_reporter_registry.cpp
     ${SOURCES_DIR}/internal/catch_result_type.cpp
     ${SOURCES_DIR}/internal/catch_run_context.cpp

src/catch2/catch_all.hpp

@@ -80,6 +80,7 @@
 #include <catch2/internal/catch_polyfills.hpp>
 #include <catch2/internal/catch_preprocessor.hpp>
 #include <catch2/internal/catch_random_number_generator.hpp>
+#include <catch2/internal/catch_random_seed_generation.hpp>
 #include <catch2/internal/catch_reporter_registry.hpp>
 #include <catch2/internal/catch_result_type.hpp>
 #include <catch2/internal/catch_run_context.hpp>

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

src/catch2/internal/catch_random_seed_generation.hpp

@@ -0,0 +1,26 @@
+
+//              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
+#ifndef CATCH_RANDOM_SEED_GENERATION_HPP_INCLUDED
+#define CATCH_RANDOM_SEED_GENERATION_HPP_INCLUDED
+
+#include <cstdint>
+
+namespace Catch {
+
+    enum class GenerateFrom {
+        Time,
+        RandomDevice,
+        //! Currently equivalent to RandomDevice, but can change at any point
+        Default
+    };
+
+    std::uint32_t generateRandomSeed(GenerateFrom from);
+
+} // end namespace Catch
+
+#endif // CATCH_RANDOM_SEED_GENERATION_HPP_INCLUDED