通过指向外部jar以编程方式运行testNG会引发ClassNotFoundException

Question

I want to run TestNG tests programmatically by pointing to a jar which contains the test classes. For this, firstly the testng.xml is parsed and the classes are taken. Then each class is loaded into the classpath using the URLCLassLoader . But this throws org.testng.TestNGException: Cannot find class in classpath: exception.

Below is the code I tried

public void execute() {
    String testNGXmlPath = "/path/to/testng.xml";
    try {
        getClassesToLoad(testNGXmlPath);
    } catch (ParserConfigurationException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (SAXException e) {
        e.printStackTrace();
    }
    TestNG testng = new TestNG();
    List<String> suites = Lists.newArrayList();
    suites.add(testNGXmlPath);
    testng.setTestSuites(suites);
    testng.run();
}

public void getClassesToLoad(String path) throws ParserConfigurationException, IOException, SAXException {
    File inputFile = new File(path);
    DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
    Document doc = dBuilder.parse(inputFile);
    doc.getDocumentElement().normalize();
    NodeList nodeList = doc.getElementsByTagName("class");
    Element element;
    Node node;
    NamedNodeMap namedNodeMap;

    int i, length;
    length = nodeList.getLength();
    for (int j=0; j < length; j++) {
        element = (Element)nodeList.item(j);
        namedNodeMap = element.getAttributes();
        if (namedNodeMap != null) {
            for (i=0; i<namedNodeMap.getLength(); i++) {
                node = namedNodeMap.item(i);
                if (node.getNodeName() == "name") {
                    try {
                        loadClass("/path/to/testng.sample-1.0-SNAPSHOT.jar", node.getNodeValue());
                    } catch (ClassNotFoundException e1) {
                        e1.printStackTrace();
                    }
                }
            }
        }
    }
}

public static void loadClass(String jarFilePath, String className) throws MalformedURLException,
        ClassNotFoundException {
    File jarFile  = new File(jarFilePath);
    if (jarFile.isFile()) {
        URL url = jarFile.toURL();
        URL[] urls = new URL[] { url };
        ClassLoader cl = new URLClassLoader(urls);
        cl.loadClass(className);
    }
}

Answer 1

You are loading the class loader using the URLClassLoader, but for the classes that were loaded by your class loader to be visible to the current ContextualClassLoader, you need to set it up.

Please try doing it via Thread.currentThread().setContextClassLoader(); within your loadClass() method and then try running your test. This would ensure that when TestNG kicks in, it uses the ContextClassLoader that you injected to the current thread, to be used to load classes and thus help you get past your ClassNotFoundException

Answer 2

If your intention is to run your tests from a jar, you can simply package them and run using your xml.
Refer to the commandline section of the testng documentation .

Can refer to these steps if yours is a maven project :