feat: impl lifecycle with tests

tests/engine/lifecycle_test.cpp

@@ -0,0 +1,64 @@
+#include "engine/core/engine.hpp"
+#include "engine/core/engine_module.hpp"
+#include "engine/utils/rev_range.hpp"
+#include <cassert>
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <unordered_map>
+
+bool onInitWasCalled = false;
+bool onStartWasCalled = false;
+bool onUpdateWasCalled = false;
+bool onStopWasCalled = false;
+
+class TestModule : public MscEngineModule
+{
+public:
+  std::string getName() const override { return "test_mod"; }
+  std::uint16_t getRev() const override { return 1; }
+  const std::unordered_map<std::string, MscRevisionRange> &
+  getDependencies() const override
+  {
+    static const std::unordered_map<std::string, MscRevisionRange> deps{};
+    return deps;
+  }
+
+  void onInitialize(IMscEngineModuleAPI &engine) override
+  {
+    onInitWasCalled = true;
+  }
+
+  void onStart(IMscEngineModuleAPI &engine) override
+  {
+    onStartWasCalled = true;
+  }
+
+  void onUpdate(IMscEngineModuleAPI &engine,
+                IMscEngineModuleAPI::clock::duration dt) override
+  {
+    onUpdateWasCalled = true;
+    engine.requestStop();
+  }
+
+  void onStop(IMscEngineModuleAPI &engine) override { onStopWasCalled = true; }
+
+  void onDestory(IMscEngineModuleAPI &engine) override {}
+};
+
+void testStates()
+{
+  MscEngine engine({std::make_shared<TestModule>()});
+  engine.start();
+
+  assert(onInitWasCalled);
+  assert(onStartWasCalled);
+  assert(onUpdateWasCalled);
+  assert(onStopWasCalled);
+}
+
+int main()
+{
+  testStates();
+  return 0;
+}