feat: ETLng loader basics (#1808)

For #1597

tests/common/util/MockLoadBalancer.hpp

@@ -19,6 +19,9 @@
 
 #pragma once
 
+#include "etl/ETLState.hpp"
+#include "etlng/InitialLoadObserverInterface.hpp"
+#include "etlng/LoadBalancerInterface.hpp"
 #include "rpc/Errors.hpp"
 #include "util/FakeFetchResponse.hpp"
 
@@ -28,10 +31,12 @@
 #include <boost/json/value.hpp>
 #include <gmock/gmock.h>
 
+#include <chrono>
 #include <cstdint>
 #include <expected>
 #include <optional>
 #include <string>
+#include <vector>
 
 struct MockLoadBalancer {
     using RawLedgerObjectType = FakeLedgerObject;
@@ -48,3 +53,36 @@ struct MockLoadBalancer {
         (const)
     );
 };
+
+struct MockNgLoadBalancer : etlng::LoadBalancerInterface {
+    using RawLedgerObjectType = FakeLedgerObject;
+
+    MOCK_METHOD(
+        std::vector<std::string>,
+        loadInitialLedger,
+        (uint32_t, etlng::InitialLoadObserverInterface&, std::chrono::steady_clock::duration),
+        (override)
+    );
+    MOCK_METHOD(
+        std::vector<std::string>,
+        loadInitialLedger,
+        (uint32_t, std::chrono::steady_clock::duration),
+        (override)
+    );
+    MOCK_METHOD(
+        OptionalGetLedgerResponseType,
+        fetchLedger,
+        (uint32_t, bool, bool, std::chrono::steady_clock::duration),
+        (override)
+    );
+    MOCK_METHOD(boost::json::value, toJson, (), (const, override));
+    MOCK_METHOD(std::optional<etl::ETLState>, getETLState, (), (noexcept, override));
+
+    using ForwardToRippledReturnType = std::expected<boost::json::object, rpc::ClioError>;
+    MOCK_METHOD(
+        ForwardToRippledReturnType,
+        forwardToRippled,
+        (boost::json::object const&, std::optional<std::string> const&, bool, boost::asio::yield_context),
+        (override)
+    );
+};