Method AddEnvironment

tests/gtest/gtest-all.cc:6193–6200

Registers and returns a global test environment. When a test program is run, all global test environments will be set-up in the order they were registered. After all tests in the program have finished, all global test environments will be torn-down in the reverse* order they were registered. The UnitTest object takes ownership of the given environment. We don't protect this under mutex_, as we

// We don't protect this under mutex_, as we only support calling it
// from the main thread.
Environment* UnitTest::AddEnvironment(Environment* env) {
  if (env == nullptr) {
    return nullptr;
  }

  impl_->environments().push_back(env);
  return env;
}

// Adds a TestPartResult to the current TestResult object.  All Google Test
// assertion macros (e.g. ASSERT_TRUE, EXPECT_EQ, etc) eventually call