revive ptrace #5983

only: quality in software begins with proper practices like TDD

firmware/console/binary/tooth_logger.cpp

@@ -127,6 +127,7 @@ void DisableToothLogger() {
 	setToothLogReady(false);
 
 	// Release the big buffer for another user
+	// C++ magic: here we are calling BigBufferHandle::operator=() with empty instance
 	bufferHandle = {};
 	buffers = nullptr;
 }

firmware/controllers/core/big_buffer.cpp

@@ -8,6 +8,12 @@ static BigBufferUser s_currentUser;
 // we've only observed issue on F7 in -Os compiler configuration but technically all processors care
 static uint32_t s_bigBuffer[BIG_BUFFER_SIZE / sizeof(uint32_t)];
 
+#if EFI_UNIT_TEST
+BigBufferUser &getBigBufferCurrentUser() {
+  return s_currentUser;
+}
+#endif // EFI_UNIT_TEST
+
 static void releaseBuffer(void* bufferPtr, BigBufferUser user) {
 	if (bufferPtr != &s_bigBuffer || user != s_currentUser) {
 		// todo: panic!

unit_tests/tests/test_big_buffer.cpp

@@ -0,0 +1,10 @@
+#include "pch.h"
+
+BigBufferUser &getBigBufferCurrentUser();
+
+TEST(BigBuffer, CppMagic) {
+  BigBufferHandle h = getBigBuffer(BigBufferUser::ToothLogger);
+  ASSERT_EQ(getBigBufferCurrentUser(), BigBufferUser::ToothLogger);
+  h = {};
+  ASSERT_EQ(getBigBufferCurrentUser(), BigBufferUser::ToothLogger);
+}

unit_tests/tests/tests.mk

@@ -58,6 +58,7 @@ TESTS_SRC_CPP = \
 	tests/test_change_engine_type.cpp \
 	tests/util/test_scaled_channel.cpp \
 	tests/util/test_timer.cpp \
+	tests/test_big_buffer.cpp \
 	tests/system/test_periodic_thread_controller.cpp \
 	tests/test_util.cpp \
 	tests/test_start_stop.cpp \