[K/N][Runtime tests] Support << operator for thread states

kotlin-native/runtime/src/mm/cpp/TestSupport.cpp

@@ -11,6 +11,7 @@
 #include "GlobalsRegistry.hpp"
 #include "TestSupport.hpp"
 #include "ThreadData.hpp"
+#include "ThreadState.hpp"
 
 using namespace kotlin;
 
@@ -57,4 +58,8 @@ extern "C" void Kotlin_TestSupport_AssertClearGlobalState() {
 void kotlin::DeinitMemoryForTests(MemoryState* memoryState) {
     DeinitMemory(memoryState, false);
     mm::ThreadRegistry::TestSupport::ClearCurrentThreadData();
+}
+
+std::ostream& kotlin::operator<<(std::ostream& stream, ThreadState state) {
+    return stream << ThreadStateName(state);
 }

kotlin-native/runtime/src/mm/cpp/TestSupport.hpp

@@ -5,6 +5,8 @@
 
 #include "../../main/cpp/TestSupport.hpp"
 
+#include <ostream>
+
 #include "MemoryPrivate.hpp"
 #include "ThreadData.hpp"
 
@@ -16,4 +18,8 @@ inline void RunInNewThread(std::function<void(mm::ThreadData&)> f) {
     });
 }
 
+// Overload the << operator for ThreadState to allow the GTest runner
+// to pretty print ThreadState constants.
+std::ostream& operator<<(std::ostream& stream, ThreadState state);
+
 } // namespace kotlin