@Test public void testAddUrlToClasspath() throws Exception { ClassLoader systemClassLoader = ClassLoader.getSystemClassLoader(); assertTrue(systemClassLoader instanceof URLClassLoader); URLClassLoader classLoader = (URLClassLoader) systemClassLoader; URL sampleUrl = new File("src").toURI().toURL(); String classpath = classpathAsString(classLoader); assertNotSubString(sampleUrl.toString(), classpath); FileUtil.addUrlToClasspath(sampleUrl); classpath = classpathAsString(classLoader); assertSubString(sampleUrl.toString(), classpath); }