Best way to recognize test classes?

Question

I am building a program that recognizes test classes and gives the coder an idea how much test code he wrote compared to the actual source code. My question is how can I make the program recognize a test class despite the type of tests that has been used? what is the main sign that you may find in a test class? Is it the @Test notation? If so how to handle it?

This is a piece of code of a class that I made to recognize test classes:

public void walk(String path) throws FileNotFoundException {
    int countFiles = 0;
    File root = new File(path);
    File[] list = root.listFiles();
    if (list == null) {
        return;
    }

    for (File f : list) {
        if (f.isDirectory()) {
            walk(f.getAbsolutePath());
        }

        if (f.getName().endsWith(".java")) {

            System.out.println("File:" + f.getName());
               Scanner sc2 = new Scanner(f);

            while (sc2.hasNextLine()) {

                count++;

                String str = sc2.nextLine();

                for (int i = 0; i < str.length(); i++) {
                    if(str.equals("@Test")){
                    System.out.println("this a test clsee!");
                }

But unfortunately my idea is not working. So what can I do?

Answer 1

I realize this might not be exactly the answer you are looking for, but let me give you two alternative ideas nonetheless.

1. If you are using maven or gradle as your build tool, you should have all your test classes in the src/test/java folder anyway, making it easy to distinguish them from your production code (located in the src/main/java folder). Other tools might have similar structures. If yours doesn't you might want to consider switching.

   Once you have your test code and your productive code in different folders, you can simply count all *.java files within those folder structures (or write a bat/bash/whatever script to do it for you).

2. Since the pure amount of test code doesn't really tell you anything about your actual test coverage, you might want to look for a tool that helps you measure this coverage and focus on the quality rather than the quantity of your tests.

   If you are using Eclipse, there is e.g. EclEmma (which is maybe not the only one and not the best one but simply the one I am using). It adds a new launch mode to Eclipse and you can then start your unit tests in Coverage mode. In this mode, EclEmma records which lines of your production code are being executed when your test runs, giving you a good idea of which parts of your code are tested and which are not. It also computes some statistics regarding the percentage of lines or branches covered to help you identify weak spots.

(Now to at least quickly address your code: In theory your approach should work. In practice it looks like you should read up on string comparison in java. It might be worth a shot to replace your str.equals("@Test") loop with a simple str.contains("@Test").)

Answer 2

1. Don't use str.equals("@Test"), use str.contains("@Test")
2. Also good if you check str.contains("org.testng"), str.contains("org.junit"), str.contains("org.easymock"), str.contains("org.mockito") and so on.

Upd: For example, instead of code:

Scanner sc2 = new Scanner(f);

while (sc2.hasNextLine()) {

    count++;

    String str = sc2.nextLine();

    for (int i = 0; i < str.length(); i++) {
        if(str.equals("@Test")){
        System.out.println("this a test clsee!");

You should use code:

   Scanner sc2 = new Scanner(f);
   boolean flag = false;
   while (sc2.hasNextLine() && !flag) {
        String str = sc2.nextLine();
        if(str.contains("@Test")){
            flag = true;
        }
  }
  if(flag) {
        System.out.println("this a test clsee!");
  } 

Answer 3

I not sure if this is what you are looking for. After you get file name follow below steps.

Classfile.class.getMethods()

Iterate through methods array and check for annotation class

method.getAnnotation(Test.class)

As suggested by others it's always a better practice not to club test classes with businesses code.

I have added full code snippet here.

public class ClassFinder {

private static final char PKG_SEPARATOR = '.';

private static final char DIR_SEPARATOR = '/';

private static final String CLASS_FILE_SUFFIX = ".class";

private static final String BAD_PACKAGE_ERROR = "Unable to get resources from path '%s'. Are you sure the package '%s' exists?";

public static List<Class<?>> find(String scannedPackage) {
    String scannedPath = scannedPackage.replace(PKG_SEPARATOR, DIR_SEPARATOR);
    URL scannedUrl = Thread.currentThread().getContextClassLoader().getResource(scannedPath);
    if (scannedUrl == null) {
        throw new IllegalArgumentException(String.format(BAD_PACKAGE_ERROR, scannedPath, scannedPackage));
    }
    File scannedDir = new File(scannedUrl.getFile());
    List<Class<?>> classes = new ArrayList<Class<?>>();
    for (File file : scannedDir.listFiles()) {
        classes.addAll(find(file, scannedPackage));
    }
    return classes;
}

private static List<Class<?>> find(File file, String scannedPackage) {
    List<Class<?>> classes = new ArrayList<Class<?>>();
    String resource = scannedPackage + PKG_SEPARATOR + file.getName();
    if (file.isDirectory()) {
        for (File child : file.listFiles()) {
            classes.addAll(find(child, resource));
        }
    } else if (resource.endsWith(CLASS_FILE_SUFFIX)) {
        int endIndex = resource.length() - CLASS_FILE_SUFFIX.length();
        String className = resource.substring(0, endIndex);
        try {
            classes.add(Class.forName(className));
        } catch (ClassNotFoundException ignore) {
        }
    }
    return classes;
}

public static void main(String[] args) {
    List<Class<?>> classes = ClassFinder.find("com.vijay.junitapp4");
    Method[] methods = null;
    for (Class<?> class1 : classes) {
        methods = class1.getMethods();
        Test test = null;
        for (int j = 0; j < methods.length; j++) {
            test = methods[j].getAnnotation(Test.class);
            if(null != test){
                System.out.println("we found a teat case");
                break;
            }
        }
    }
}

}