Answer by blacktide for Unit testing c++. How to test private members?

Another solution that doesn't require you to add any gtest headers or macros to your production code could be to mark the private members as protected and create a derived class used in your tests with public functions exposing the private members.

Class to be tested:

#include <cstdint>class Widget {protected:    uint8_t foo;    uint8_t bar;    void baz();}

And the test class:

#include "gtest/gtest.h"#include <cstdint>#include "../src/widget.h"// create a "test" class derived from your production classclass TestWidget : public Widget {public:    // create public methods that expose the private members    uint8_t getFoo() {        return foo;    }    void callBar() {        bar();    }}TEST(WidgetTests, TestFoo) {    // Use the derived class in your tests    TestWidget widget;    // call a protected method    widget.callBar();    // check the value of a protected member    EXPECT_EQ(widget.getFoo(), 10);}

Of course the main caveat here is that you must mark the private members you need to access as protected, but it's another option if you want to keep the "test" code out of your production classes.