GTest

GTest, short for Google Test, is an open-source C++ testing framework developed by Google and widely used for unit testing C++ code. It provides a rich set of assertions, test fixtures, and utilities that help write portable, maintainable tests with a consistent style.

Key features include a large collection of assertion macros (such as EXPECT_EQ and ASSERT_NE), test fixtures via TEST_F, and test suites created with TEST. It supports fatal assertions that abort the current test and non-fatal assertions that allow the test to continue. It also supports parameterized testing with TEST_P and INSTANTIATE_TEST_SUITE_P, as well as type-parameterized tests with TYPED_TEST and TYPED_TEST_SUITE. Death tests enable asserting that a program crashes or terminates as expected, usually in a separate process. The framework provides test discovery and a test runner, with command-line options to filter tests, repeat runs, and configure output formats such as XML or JSON.

Integration and usage: tests are compiled into a binary that links against the gtest library; in some configurations gtest can be used in a header-only fashion. Build systems such as CMake and Bazel provide built-in support. It integrates with Google Mock, a separate mocking framework that shares the same testing API.

History and license: Google Test was released by Google in the late 2000s and has since become one of the most widely used C++ testing frameworks. It is released under a BSD-style license and is maintained as an open-source project with active contributions.