Function maybeLoadPythonRequest

packages/python-analysis/src/manifest/package.ts:704–734

(
  root: AbsPath,
  subdir: RelPath
)

 * Read and parse a .python-version file if it exists in the given subdirectory.
 */
async function maybeLoadPythonRequest(
  root: AbsPath,
  subdir: RelPath
): Promise<PythonVersionConfig | null> {
  const dotPythonVersionRelPath: RelPath = path.join(subdir, '.python-version');
  const dotPythonVersionPath: AbsPath = path.join(
    root,
    dotPythonVersionRelPath
  );
  const data: string | null = await readFileTextIfExists(dotPythonVersionPath);

  if (data == null) {
    return null;
  }

  const pyreq = parsePythonVersionFile(data);
  if (pyreq == null) {
    throw new PythonAnalysisError({
      message: `could not parse .python-version file: no valid Python version requests found`,
      code: 'PYTHON_VERSION_FILE_PARSE_ERROR',
      path: dotPythonVersionRelPath,
    });
  }

  return {
    kind: PythonConfigKind.PythonVersion,
    path: dotPythonVersionRelPath,
    data: pyreq,
    specifier: data.trim(),
  };
}