@Override
public Injector getInjector(IClass iClass) {
  Annotation annotation = AnnotationHelper.findAnnotationSuperClasses(Guice.class, iClass.getRealClass());
  if (annotation == null) return null;
  if (iClass instanceof TestClass) {
    iClass = ((TestClass)iClass).getIClass();
  }
  if (!(iClass instanceof ClassImpl)) return null;
  Injector parentInjector = ((ClassImpl)iClass).getParentInjector();

  Guice guice = (Guice) annotation;
  List<Module> moduleInstances = Lists.newArrayList(getModules(guice, parentInjector, iClass.getRealClass()));

  // Reuse the previous injector, if any
  Injector injector = getInjector(moduleInstances);
  if (injector == null) {
    injector = parentInjector.createChildInjector(moduleInstances);
    addInjector(moduleInstances, injector);
  }
  return injector;
}
 

/** Guessing whether or not a class is a test class is an imperfect art form. */
private boolean mightBeATestClass(Class<?> klass) {
  int klassModifiers = klass.getModifiers();
  // Test classes must be public, non-abstract, non-interface
  if (!Modifier.isPublic(klassModifiers)
      || Modifier.isInterface(klassModifiers)
      || Modifier.isAbstract(klassModifiers)) {
    return false;
  }
  // Test classes must either have a public, no-arg constructor, or have a constructor that
  // initializes using dependency injection, via the org.testng.annotations.Guice annotation on
  // the class and the com.google.inject.Inject or javax.inject.Inject annotation on the
  // constructor.
  boolean foundPublicNoArgConstructor = false;
  boolean foundInjectedConstructor = false;
  boolean hasGuiceAnnotation = klass.getAnnotationsByType(Guice.class).length > 0;
  for (Constructor<?> c : klass.getConstructors()) {
    if (Modifier.isPublic(c.getModifiers())) {
      if (c.getParameterCount() == 0) {
        foundPublicNoArgConstructor = true;
      }
      if (hasGuiceAnnotation
          && (c.getAnnotationsByType(com.google.inject.Inject.class).length > 0
              || c.getAnnotationsByType(javax.inject.Inject.class).length > 0)) {
        foundInjectedConstructor = true;
      }
    }
  }
  if (!foundPublicNoArgConstructor && !foundInjectedConstructor) {
    return false;
  }
  // Test classes must have at least one public test method (or something that generates tests)
  boolean hasAtLeastOneTestMethod = false;
  for (Method m : klass.getMethods()) {
    if (Modifier.isPublic(m.getModifiers()) && m.getAnnotation(Test.class) != null) {
      hasAtLeastOneTestMethod = true;
    }
    if (Modifier.isPublic(m.getModifiers()) && m.getAnnotation(Factory.class) != null) {
      hasAtLeastOneTestMethod = true; // technically, not *quite* true, but close enough
    }
  }
  return hasAtLeastOneTestMethod;
}