tests: Shared subtree for two sysrepo processes

Test whether Sysrepo correctly provides the data when the data are
handled by two processes. This is a simplified setup from the real
use-case where cla-sysrepo and velia will manage the data from the
the ietf-hardware module.

Change-Id: Iae9961e66110e567e52aad12e5cea229633999cf
diff --git a/tests/sysrepo_two-daemons_daemon.cpp b/tests/sysrepo_two-daemons_daemon.cpp
new file mode 100644
index 0000000..6b79b2d
--- /dev/null
+++ b/tests/sysrepo_two-daemons_daemon.cpp
@@ -0,0 +1,109 @@
+#include <csignal>
+#include <cstring>
+#include <fstream>
+#include <map>
+#include <sysrepo-cpp/Session.hpp>
+#include <unistd.h>
+
+using namespace std::string_literals;
+
+volatile sig_atomic_t g_exit_application = 0;
+
+static const std::string MODULE_NAME = "ietf-hardware";
+static const std::string MODULE_PREFIX = "/" + MODULE_NAME + ":hardware";
+
+void valuesToYang(const std::map<std::string, std::string>& values, std::shared_ptr<::sysrepo::Session> session, std::shared_ptr<libyang::Data_Node>& parent, const std::string& prefix)
+{
+    for (const auto& [propertyName, value] : values) {
+        if (!parent) {
+            parent = std::make_shared<libyang::Data_Node>(
+                session->get_context(),
+                (prefix + propertyName).c_str(),
+                value.c_str(),
+                LYD_ANYDATA_CONSTSTRING,
+                LYD_PATH_OPT_OUTPUT);
+        } else {
+            parent->new_path(
+                session->get_context(),
+                (prefix + propertyName).c_str(),
+                value.c_str(),
+                LYD_ANYDATA_CONSTSTRING,
+                LYD_PATH_OPT_OUTPUT);
+        }
+    }
+}
+
+void usage(const char* progName)
+{
+    std::cout << "Usage: " << progName << "--subscribe|--setitem" << std::endl;
+}
+
+int main(int argc, char* argv[])
+{
+    if (argc != 2) {
+        usage(argv[0]);
+        return 1;
+    }
+
+    bool isDaemonSubscribe = argv[1] == "--subscribe"s;
+    bool isDaemonSetItem = argv[1] == "--set-item"s;
+
+    if (isDaemonSubscribe == isDaemonSetItem) {
+        usage(argv[0]);
+        return 1;
+    }
+
+    auto srConn = std::make_shared<sysrepo::Connection>();
+    auto srSess = std::make_shared<sysrepo::Session>(srConn);
+
+    std::shared_ptr<sysrepo::Subscribe> srSubs;
+    uint32_t srLastRequestId = 0; // for subscribe part
+
+    std::map<std::string, std::string> data;
+
+    if (isDaemonSubscribe) {
+        data = {
+            {"/component[name='ne']/description", "This data was brought to you by process 2 (subscr)."},
+            {"/component[name='ne:ctrl']/class", "iana-hardware:module"},
+        };
+
+        srSubs = std::make_shared<sysrepo::Subscribe>(srSess);
+
+        srSubs->oper_get_items_subscribe(
+            MODULE_NAME.c_str(),
+            [&](std::shared_ptr<::sysrepo::Session> session, [[maybe_unused]] const char* module_name, [[maybe_unused]] const char* xpath, [[maybe_unused]] const char* request_xpath, uint32_t request_id, std::shared_ptr<libyang::Data_Node>& parent) {
+                if (srLastRequestId == request_id) {
+                    return SR_ERR_OK;
+                }
+                srLastRequestId = request_id;
+
+                valuesToYang(data, session, parent, MODULE_PREFIX);
+                return SR_ERR_OK;
+            },
+            (MODULE_PREFIX + "/*").c_str(),
+            SR_SUBSCR_PASSIVE | SR_SUBSCR_OPER_MERGE | SR_SUBSCR_CTX_REUSE);
+    } else if (isDaemonSetItem) {
+        data = {
+            {"/component[name='ne']/class", "iana-hardware:module"},
+            {"/component[name='ne:edfa']/class", "iana-hardware:module"},
+        };
+
+        srSess->session_switch_ds(SR_DS_OPERATIONAL);
+        for (const auto& [k, v] : data) {
+            srSess->set_item_str((MODULE_PREFIX + k).c_str(), v.c_str());
+        }
+        srSess->apply_changes();
+        srSess->session_switch_ds(SR_DS_RUNNING);
+    }
+
+    // touch a file so somebody can read that sysrepo things are initialised
+    {
+        std::string filename = std::to_string(getpid()) + ".sysrepo";
+        std::ofstream ofs(filename);
+        ofs << "";
+    }
+
+    sleep(1000); // I guess, this is plenty of seconds, right?
+
+    return 0;
+}