public static String getTestClass() {
    StackTraceElement element = getFirstTestElement(new Throwable().getStackTrace());
    if (element == null) {
      return UNKNOWN;
    }
    return element.getClassName();
  }
Get the current test class in a standard JUnit3 or JUnit4 test, or "unknown" if we couldn't
detect it.
core/src/main/java/com/facebook/testing/screenshot/internal/TestNameDetector.java