@Test public void testConfig() { // tests around Config // set the custom props, then override with defaults System.setProperty("environment", "custom"); final URL defaultPropsUrl = ConfigurationTest.class.getResource("/default.properties"); Configuration.INSTANCE.addDefaultProperties(defaultPropsUrl, "default"); // overridden Assert.assertThat(Configuration.INSTANCE.getString("overridden.key"), is("overridden")); // default Assert.assertThat(Configuration.INSTANCE.getString("default.key"), is("default-key")); // custom Assert.assertThat(Configuration.INSTANCE.getString("custom.key"), is("custom-key")); Assert.assertNull(Configuration.INSTANCE.getString("non-existant")); }