add c-api test

test/test_ipc_python_cpp.cpp

@@ -0,0 +1,47 @@
+#include <chrono>
+#include <cmath>
+#include <thread>
+
+#include <fmt/core.h>
+
+#include "ipc/api.hpp"
+
+int
+main(int /* argc */, char** /* argv */)
+{
+    using fmt::format;
+    using fmt::print;
+    using ipc::Ipc;
+    using namespace std::chrono_literals;
+
+    int verbose = 0;
+    ipc::init();  // default name
+
+    ipc::start_external("python test_server.py", true);
+
+    print("[client] pre-start\n");
+    auto client = Ipc(false, verbose);
+    print("[client] start\n");
+
+    double answer;
+    auto hline = "\n------------------------\n";
+    for (int i = 2; i <= 5; ++i) {
+        std::this_thread::sleep_for(500ms);
+        print(hline);
+
+        {
+            client.write(i);
+            print("[client] write int({})\n", i);
+        }
+
+        {
+            client.read(answer);
+            print("[client] read double({:.2e})\n", answer);
+        }
+    }
+
+    print(hline);
+    print("[client] finish the work\n\n");
+
+    return 0;
+}