install

sudo apt install libgtest-dev

installation check

dpkg -l | grep gtest
# or
apt list --installed | grep gtest

check GTest headers

ls /usr/include/gtest/gtest.h
# or
find /usr -name "gtest.h" 2>/dev/null

Check if GTest is available using pkg-config

pkg-config --modversion gtest

application

simple application

cmake_minimum_required(VERSION 3.10)
project(MyTestProject)

# Enable testing: Without calling `enable_testing()`, you cannot use the `add_test()` command, and testing features will not be available in your project.
enable_testing()

# Find Google Test
find_package(GTest REQUIRED)

# Include directories for Google Test
include_directories(${GTEST_INCLUDE_DIRS})

# Add your test source file
add_executable(my_tests my_tests.cpp)

# Link Google Test libraries
target_link_libraries(my_tests GTest::GTest GTest::Main)
# target_link_libraries(my_tests  gtest gtest_main)


# Add the test to CTest: registers a test with the CMake testing system; You can define and run multiple tests in an organized way; Works seamlessly with continuous integration systems to automate testing pipelines; You can pass specific arguments to your test binary.
add_test(NAME MyTests COMMAND my_tests)

#include <gtest/gtest.h>

TEST(Test, test1)
{

}

int main(int argc, char **argv)
{
  ::testing::InitGoogleTest(&argc, argv);
  return RUN_ALL_TESTS();
}

# run a specific test
./test_example --gtest_filter=AdditionTest.PositiveNumbers

# Run all tests except one
./test_example --gtest_filter=-AdditionTest.PositiveNumbers

Using Environment Variables for Custom Behaviors

#include <cstdlib>  // For std::setenv

int main(int argc, char **argv) {
    ::testing::InitGoogleTest(&argc, argv);
    int result = RUN_ALL_TESTS();

    if (result != 0) {
        std::setenv("GTEST_FAILED", "1", 1);  // Set an environment variable
    }

    return result;
}

Then, in a shell script or CI/CD pipeline, you can check:

if [ "$GTEST_FAILED" == "1" ]; then
    echo "Tests failed"
    exit 1
fi

assertion

Basic Assertions

EXPECT_EQ(val1, val2); // Check if values are equal.

EXPECT_NE(val1, val2); // Check if values are not equal.

EXPECT_LT(val1, val2); // Check if val1 is less than val2.

EXPECT_LE(val1, val2); // Check if val1 is less than or equal to val2.

EXPECT_GT(val1, val2); // Check if val1 is greater than val2.

EXPECT_GE(val1, val2); // Check if val1 is greater than or equal to val2.

Fatal Assertions (Stops Test Immediately)

ASSERT_EQ(val1, val2)

ASSERT_NE(val1, val2)

ASSERT_TRUE(condition)

ASSERT_FALSE(condition)

Returning Different Exit Codes Based on Failure Count

#include <gtest/gtest.h>

int main(int argc, char **argv) {
  ::testing::InitGoogleTest(&argc, argv);
  int result = RUN_ALL_TESTS();

  if (testing::UnitTest::GetInstance()->failed_test_count() > 5) 
  {
    return 10;  // Return a specific code if more than 5 tests fail
  }
  return result;  // Default behavior otherwise
}

This approach helps distinguish between minor and major failures.