@Test
public void testGetInternalProperty() {

    Map<String, String> map = new HashMap<>();
    map.put(MOCK_KEY, MOCK_VALUE);
    try {
        setEnv(map);
        EnvironmentConfiguration configuration = new EnvironmentConfiguration();
        // this UT maybe only works on particular platform, assert only when value is not null.
        Assertions.assertEquals(MOCK_VALUE, configuration.getInternalProperty("dubbo.key"));
        Assertions.assertEquals(MOCK_VALUE, configuration.getInternalProperty("key"));
        Assertions.assertEquals(MOCK_VALUE, configuration.getInternalProperty("dubbo_key"));
        Assertions.assertEquals(MOCK_VALUE, configuration.getInternalProperty(MOCK_KEY));
    } catch (Exception e) {
        // skip test.
        e.printStackTrace();
    }
}