TEST_SYSTEM_VARIABLE
ATF_CHECK(getenv(TEST_SYSTEM_VARIABLE) != NULL);
ATF_CHECK(getenv(TEST_SYSTEM_VARIABLE) == NULL);
ATF_CHECK(getenv(TEST_SYSTEM_VARIABLE) != NULL);
ATF_CHECK(getenv(TEST_SYSTEM_VARIABLE) == NULL);
ATF_CHECK(setenv(TEST_SYSTEM_VARIABLE, "test", 0) != -1);
ATF_CHECK_STREQ(getenv(TEST_SYSTEM_VARIABLE), "test");