Usage: <main class> [options] The XML suite files to run
  Options:
    -configfailurepolicy
      Configuration failure policy (skip or continue)
    -d
      Output directory
    -dataproviderthreadcount
      Number of threads to use when running data providers
    -excludegroups
      Comma-separated list of group names to  exclude
    -groups
      Comma-separated list of group names to be run
    -junit
      JUnit mode
      Default: false
    -listener
      List of .class files or list of class names implementing ITestListener
      or ISuiteListener
    -methods
      Comma separated of test methods
      Default: []
    -methodselectors
      List of .class files or list of class names implementing IMethodSelector
    -mixed
      Mixed mode - autodetect the type of current test and run it with
      appropriate runner
      Default: false
    -objectfactory
      List of .class files or list of class names implementing
      ITestRunnerFactory
    -parallel
      Parallel mode (methods, tests or classes)
      Possible Values: [tests, methods, classes, instances, none, true, false]
    -port
      The port
    -reporter
      Extended configuration for custom report listener
    -suitename
      Default name of test suite, if not specified in suite definition file or
      source code
    -suitethreadpoolsize
      Size of the thread pool to use to run suites
      Default: 1
    -testclass
      The list of test classes
    -testjar
      A jar file containing the tests
    -testname
      Default name of test, if not specified in suitedefinition file or source
      code
    -testnames
      The list of test names to run
    -testrunfactory, -testRunFactory
      The factory used to create tests
    -threadcount
      Number of threads to use when running tests in parallel
    -usedefaultlisteners
      Whether to use the default listeners
      Default: true
    -log, -verbose
      Level of verbosity
    -xmlpathinjar
      The full path to the xml file inside the jar file (only valid if
      -testjar was specified)
      Default: testng.xml

You need to specify at least one testng.xml, one class or one method