config: extract initial paths/nodeids args logic to a function

Will be reused in the next commit.

src/_pytest/config/__init__.py

@@ -1223,6 +1223,49 @@ def _validate_args(self, args: List[str], via: str) -> List[str]:
 
  return args
 
+ def _decide_args(
+ self,
+ *,
+ args: List[str],
+ pyargs: List[str],
+ testpaths: List[str],
+ invocation_dir: Path,
+ rootpath: Path,
+ warn: bool,
+ ) -> Tuple[List[str], ArgsSource]:
+ """Decide the args (initial paths/nodeids) to use given the relevant inputs.
+
+ :param warn: Whether can issue warnings.
+ """
+ if args:
+ source = Config.ArgsSource.ARGS
+ result = args
+ else:
+ if invocation_dir == rootpath:
+ source = Config.ArgsSource.TESTPATHS
+ if pyargs:
+ result = testpaths
+ else:
+ result = []
+ for path in testpaths:
+ result.extend(sorted(glob.iglob(path, recursive=True)))
+ if testpaths and not result:
+ if warn:
+ warning_text = (
+ "No files were found in testpaths; "
+ "consider removing or adjusting your testpaths configuration. "
+ "Searching recursively from the current directory instead."
+ )
+ self.issue_config_time_warning(
+ PytestConfigWarning(warning_text), stacklevel=3
+ )
+ else:
+ result = []
+ if not result:
+ source = Config.ArgsSource.INCOVATION_DIR
+ result = [str(invocation_dir)]
+ return result, source
+
  def _preparse(self, args: List[str], addopts: bool = True) -> None:
  if addopts:
  env_addopts = os.environ.get("PYTEST_ADDOPTS", "")
@@ -1371,34 +1414,17 @@ def parse(self, args: List[str], addopts: bool = True) -> None:
  self.hook.pytest_cmdline_preparse(config=self, args=args)
  self._parser.after_preparse = True # type: ignore
  try:
- source = Config.ArgsSource.ARGS
  args = self._parser.parse_setoption(
  args, self.option, namespace=self.option
  )
- if not args:
- if self.invocation_params.dir == self.rootpath:
- source = Config.ArgsSource.TESTPATHS
- testpaths: List[str] = self.getini("testpaths")
- if self.known_args_namespace.pyargs:
- args = testpaths
- else:
- args = []
- for path in testpaths:
- args.extend(sorted(glob.iglob(path, recursive=True)))
- if testpaths and not args:
- warning_text = (
- "No files were found in testpaths; "
- "consider removing or adjusting your testpaths configuration. "
- "Searching recursively from the current directory instead."
- )
- self.issue_config_time_warning(
- PytestConfigWarning(warning_text), stacklevel=3
- )
- if not args:
- source = Config.ArgsSource.INCOVATION_DIR
- args = [str(self.invocation_params.dir)]
- self.args = args
- self.args_source = source
+ self.args, self.args_source = self._decide_args(
+ args=args,
+ pyargs=self.known_args_namespace.pyargs,
+ testpaths=self.getini("testpaths"),
+ invocation_dir=self.invocation_params.dir,
+ rootpath=self.rootpath,
+ warn=True,
+ )
  except PrintHelp:
  pass