Connect FLTK shell to JACK engine controls and status

tests/integration/test_gui_jack.cpp

@@ -0,0 +1,60 @@
+#include "../../src/gui/main_window.hpp"
+#include <FL/Fl.H>
+#include <FL/Fl_Group.H>
+#include <chrono>
+#include <cstdio>
+#include <cstring>
+
+namespace {
+Fl_Widget *find(Fl_Group &group, const char *label)
+{
+    for (int i = 0; i < group.children(); ++i) {
+        Fl_Widget *child = group.child(i);
+        if (child->label() != nullptr && std::strstr(child->label(), label) != nullptr) return child;
+        if (auto *nested = dynamic_cast<Fl_Group *>(child)) if (auto *match = find(*nested, label)) return match;
+    }
+    return nullptr;
+}
+void pump()
+{
+    const auto end = std::chrono::steady_clock::now() + std::chrono::milliseconds(400);
+    while (std::chrono::steady_clock::now() < end) Fl::wait(0.02);
+}
+}
+#define CHECK(c) do { if (!(c)) { std::fprintf(stderr,"FAIL %s:%d: %s\n",__FILE__,__LINE__,#c); return 1; } } while (0)
+int main(int argc, char **argv)
+{
+    // Real JACK backend and real FLTK event loop. No routes, no playback data.
+    for (int iteration = 0; iteration < 3; ++iteration) {
+        MainWindow window;
+        window.show(argc, argv);
+        CHECK(find(window, "ready / stopped") != nullptr);
+        auto *play = find(window, "Play");
+        auto *stop = find(window, "Stop");
+        auto *reconnect = find(window, "Reconnect");
+        CHECK(play != nullptr && stop != nullptr && reconnect != nullptr);
+        for (int restart = 0; restart < 3; ++restart) {
+            CHECK(play->active());
+            play->do_callback();
+            pump();
+            CHECK(find(window, "running (silence") != nullptr);
+            auto *status = find(window, "JACK |");
+            CHECK(status != nullptr);
+            unsigned int rate = 0U, frames = 0U, blocks = 0U;
+            CHECK(std::sscanf(status->label(), "JACK | %u Hz | %u frames | mono | %u blocks", &rate, &frames, &blocks) == 3);
+            CHECK(rate > 0U && frames > 0U && blocks > 0U);
+            stop->do_callback();
+            CHECK(find(window, "ready / stopped") != nullptr);
+        }
+        reconnect->do_callback();
+        CHECK(find(window, "ready / stopped") != nullptr);
+        play->do_callback();
+        pump();
+        CHECK(find(window, "running (silence") != nullptr);
+        window.do_callback(); // Close with an active client; synchronizes callbacks.
+        CHECK(!window.shown());
+        pump(); // No timer may access the closed client.
+    }
+    std::puts("Live GUI/JACK start/stop/reconnect/active-close tests passed.");
+    return 0;
+}