message: Tweak arg names and behaviour of ConcurrentRunner
diff: @@ -234,11 +234,15 @@ class ConcurrentRunner:
  def add(parser):
  parser.add_argument(
  "-N",
  - help="List all sub-tests",
  + "--show-only",
  + help="List all sub-tests without executing",
  action="store_true",
  )
  parser.add_argument(
  - "-R", help="Run sub-tests whose name includes this string"
  + "-R",
  + "--regex",
  + help="Run sub-tests whose name includes this string",
  + metavar="<string>",
  )
  if add_options:
  add_options(parser)
  @@ -263,16 +267,16 @@ class ConcurrentRunner:
  }
  LOG.configure(**config)
  - if self.args.N:
  - for thread in self.threads:
  - print(thread)
  - return
  -
  - if self.args.R:
  + if self.args.regex:
  self.threads = [
  - thread for thread in self.threads if self.args.R in thread.name
  + thread for thread in self.threads if self.args.regex in thread.name
  ]
  + if self.args.show_only:
  + for thread in self.threads:
  + print(thread.name)
  + return
  +
  if max_concurrent is None:
  max_concurrent = len(self.threads)
  