refactor: Turn link-info into its own element and class (#5178)

tests/src/SignalSpy.hpp

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <QObject>
+
+#include <tuple>
+#include <vector>
+
+template <typename... Args>
+class SignalSpy : public QObject
+{
+    // Simplify the storage if there's only one argument to the signal handler.
+    using Call =
+        std::conditional_t<sizeof...(Args) == 1,
+                           std::tuple_element_t<0, std::tuple<Args...>>,
+                           std::tuple<Args...>>;
+
+public:
+    SignalSpy(auto *sender, auto method)
+    {
+        auto conn =
+            QObject::connect(sender, method, this, &SignalSpy<Args...>::slot,
+                             Qt::DirectConnection);
+        assert(conn && "Failed to connect");
+    }
+
+    bool empty() const
+    {
+        return this->calls_.empty();
+    }
+
+    size_t size() const
+    {
+        return this->calls_.size();
+    }
+
+    const std::vector<std::tuple<Args...>> &calls() const
+    {
+        return this->calls_;
+    }
+
+    void clear()
+    {
+        this->calls_.clear();
+    }
+
+    const Call &last() const
+    {
+        assert(!this->calls_.empty());
+
+        return this->calls_.back();
+    }
+
+private:
+    void slot(Args... args)
+    {
+        this->calls_.emplace_back(std::move(args)...);
+    }
+
+    std::vector<Call> calls_;
+};