added test file

Signed-off-by: Bharath <bharath.kollanur@gmail.com>

Author: kollanur

libs/core/execution/tests/unit/executor_parameters_partition_hooks.cpp

@@ -0,0 +1,129 @@
+//  Copyright (c) 2026 Bharath Kollanur
+//
+//  SPDX-License-Identifier: BSL-1.0
+//  Distributed under the Boost Software License, Version 1.0. (See accompanying
+//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <hpx/algorithm.hpp>
+#include <hpx/execution.hpp>
+#include <hpx/init.hpp>
+#include <hpx/modules/testing.hpp>
+
+#include <cstddef>
+#include <cstdint>
+#include <numeric>
+#include <vector>
+
+struct partition_hooks_parameters
+{
+    explicit partition_hooks_parameters(std::size_t max_partitions)
+      : values_(max_partitions, std::pair<std::size_t, std::size_t>{0, 0})
+      , seen_(max_partitions, 0)
+    {
+    }
+
+    template <typename Executor>
+    friend void tag_override_invoke(
+        hpx::execution::experimental::mark_partition_t,
+        partition_hooks_parameters& self, Executor&&, std::size_t partition,
+        std::size_t a, std::size_t b) noexcept
+    {
+        HPX_ASSERT(partition < self.values_.size());
+        self.values_[partition] = {a, b};
+        self.seen_[partition] = 1;
+    }
+
+    std::size_t count_seen() const
+    {
+        std::size_t c = 0;
+        for (auto v : seen_)
+            c += (v != 0);
+        return c;
+    }
+
+    std::vector<std::pair<std::size_t, std::size_t>> values_;
+    std::vector<unsigned char> seen_;
+};
+
+namespace hpx::execution::experimental {
+    template <>
+    struct is_executor_parameters<partition_hooks_parameters> : std::true_type
+    {
+    };
+}    // namespace hpx::execution::experimental
+
+void test_mark_partition_sync()
+{
+    std::vector<std::uint64_t> left(200000);
+    std::vector<std::uint64_t> right(200000);
+    std::vector<std::uint64_t> out(left.size() + right.size());
+
+    std::iota(left.begin(), left.end(), std::uint64_t(0));
+    std::iota(right.begin(), right.end(), std::uint64_t(left.size()));
+    hpx::execution::experimental::chunking_parameters exec_params{};
+    hpx::execution::experimental::collect_chunking_parameters collect_params(
+        exec_params);
+
+    partition_hooks_parameters params(left.size() + right.size());
+
+    auto policy =
+        hpx::execution::par.with(std::ref(collect_params), std::ref(params));
+    hpx::merge(policy, left.begin(), left.end(), right.begin(), right.end(),
+        out.begin());
+
+    HPX_TEST(std::is_sorted(out.begin(), out.end()));
+    HPX_TEST_EQ(params.count_seen(), exec_params.num_chunks);
+}
+
+void test_mark_partition_async()
+{
+    std::vector<std::uint64_t> left(200000);
+    std::vector<std::uint64_t> right(200000);
+    std::vector<std::uint64_t> out(left.size() + right.size());
+
+    std::iota(left.begin(), left.end(), std::uint64_t(0));
+    std::iota(right.begin(), right.end(), std::uint64_t(left.size()));
+
+    hpx::execution::experimental::chunking_parameters exec_params{};
+    hpx::execution::experimental::collect_chunking_parameters collect_params(
+        exec_params);
+
+    partition_hooks_parameters params(left.size() + right.size());
+
+    auto policy = hpx::execution::par(hpx::execution::task)
+                      .with(std::ref(params), std::ref(collect_params));
+    auto f = hpx::merge(policy, left.begin(), left.end(), right.begin(),
+        right.end(), out.begin());
+    auto result_iter = f.get();
+    HPX_UNUSED(result_iter);
+
+    HPX_TEST(std::is_sorted(out.begin(), out.end()));
+    HPX_TEST_EQ(params.count_seen(), exec_params.num_chunks);
+}
+
+int hpx_main(hpx::program_options::variables_map&)
+{
+    test_mark_partition_sync();
+    test_mark_partition_async();
+
+    return hpx::local::finalize();
+}
+
+int main(int argc, char* argv[])
+{
+    using namespace hpx::program_options;
+
+    options_description desc_commandline(
+        "Usage: " HPX_APPLICATION_STRING " [options]");
+
+    std::vector<std::string> const cfg = {"hpx.os_threads=all"};
+
+    hpx::local::init_params init_args;
+    init_args.desc_cmdline = desc_commandline;
+    init_args.cfg = cfg;
+
+    HPX_TEST_EQ_MSG(hpx::local::init(hpx_main, argc, argv, init_args), 0,
+        "HPX main exited with non-zero status");
+
+    return hpx::util::report_errors();
+}