test(automation): MockUiBackend recording test double

tests/automation/MockUiBackend.hpp

@@ -0,0 +1,59 @@
+#pragma once
+#include "slic3r/GUI/Automation/IUiBackend.hpp"
+#include <functional>
+#include <vector>
+
+namespace Slic3r { namespace GUI { namespace Automation {
+
+// Deterministic fake backend for dispatcher tests. Records every primitive call
+// and returns canned data. `tree_provider` lets a test return different trees on
+// successive dump_tree() calls (used for sync.wait_for tests).
+class MockUiBackend : public IUiBackend {
+public:
+    // Recorded calls (inspected by tests).
+    int               refresh_count = 0;
+    int               dump_count    = 0;
+    std::vector<std::string> clicked_ids;       // node.id of each click()
+    std::vector<MouseButton> click_buttons;
+    std::vector<std::string> typed_text;
+    std::vector<std::vector<KeyChord>> sent_keys;
+    int               screenshot_window_count   = 0;
+    int               screenshot_viewport_count = 0;
+
+    // Canned outputs (set by tests).
+    UiNode   tree;                                  // default tree for dump_tree
+    AppState state;
+    PngImage canned_png{ {0x89,0x50,0x4E,0x47}, 4, 4 }; // fake "PNG" bytes
+    bool     click_result = true;
+
+    // Optional: per-call tree provider (overrides `tree` when set).
+    std::function<UiNode(int /*call_index*/)> tree_provider;
+
+    void     refresh_ui() override { ++refresh_count; }
+    UiNode   dump_tree(const DumpOptions&) override {
+        const int idx = dump_count++;
+        return tree_provider ? tree_provider(idx) : tree;
+    }
+    AppState app_state() override { return state; }
+    bool     click(const UiNode& node, MouseButton button, bool /*dbl*/,
+                   const std::vector<KeyModifier>&) override {
+        clicked_ids.push_back(node.id);
+        click_buttons.push_back(button);
+        return click_result;
+    }
+    bool     type_text(const std::string& text) override {
+        typed_text.push_back(text); return true;
+    }
+    bool     send_keys(const std::vector<KeyChord>& chords) override {
+        sent_keys.push_back(chords); return true;
+    }
+    PngImage screenshot_window(const UiNode*) override {
+        ++screenshot_window_count; return canned_png;
+    }
+    PngImage screenshot_viewport3d(std::optional<int>, std::optional<int>,
+                                   std::optional<int>) override {
+        ++screenshot_viewport_count; return canned_png;
+    }
+};
+
+}}} // namespace