SystemConfiguration implements Configuration { @Override public Object getInternalProperty(String key) { return System.getProperty(key); }  @Override Object getInternalProperty(String key);  }
@Test public void testGetSysProperty() { Assertions.assertNull(sysConfig.getInternalProperty(MOCK_KEY)); Assertions.assertFalse(sysConfig.containsKey(MOCK_KEY)); Assertions.assertNull(sysConfig.getString(MOCK_KEY)); Assertions.assertNull(sysConfig.getProperty(MOCK_KEY)); System.setProperty(MOCK_KEY, MOCK_STRING_VALUE); Assertions.assertTrue(sysConfig.containsKey(MOCK_KEY)); Assertions.assertEquals(MOCK_STRING_VALUE, sysConfig.getInternalProperty(MOCK_KEY)); Assertions.assertEquals(MOCK_STRING_VALUE, sysConfig.getString(MOCK_KEY, MOCK_STRING_VALUE)); Assertions.assertEquals(MOCK_STRING_VALUE, sysConfig.getProperty(MOCK_KEY, MOCK_STRING_VALUE)); }