Function readConfig

src/configuration.ts:129–329

(
  cwd: string,
  ts: TSCommon,
  rawApiOptions: CreateOptions
)

 * @internal
 */
export function readConfig(
  cwd: string,
  ts: TSCommon,
  rawApiOptions: CreateOptions
): {
  /**
   * Path of tsconfig file if one was loaded
   */
  configFilePath: string | undefined;
  /**
   * Parsed TypeScript configuration with compilerOptions merged from all other sources (env vars, etc)
   */
  config: _ts.ParsedCommandLine;
  /**
   * ts-node options pulled from `tsconfig.json`, NOT merged with any other sources.  Merging must happen outside
   * this function.
   */
  tsNodeOptionsFromTsconfig: TsConfigOptions;
  optionBasePaths: OptionBasePaths;
} {
  // Ordered [a, b, c] where config a extends b extends c
  const configChain: Array<{
    config: any;
    basePath: string;
    configPath: string;
  }> = [];
  let config: any = { compilerOptions: {} };
  let basePath = cwd;
  let configFilePath: string | undefined = undefined;
  const projectSearchDir = resolve(cwd, rawApiOptions.projectSearchDir ?? cwd);

  const {
    fileExists = ts.sys.fileExists,
    readFile = ts.sys.readFile,
    skipProject = DEFAULTS.skipProject,
    project = DEFAULTS.project,
    tsTrace = DEFAULTS.tsTrace,
  } = rawApiOptions;

  // Read project configuration when available.
  if (!skipProject) {
    if (project) {
      const resolved = resolve(cwd, project);
      const nested = join(resolved, 'tsconfig.json');
      configFilePath = fileExists(nested) ? nested : resolved;
    } else {
      configFilePath = ts.findConfigFile(projectSearchDir, fileExists);
    }

    if (configFilePath) {
      let pathToNextConfigInChain = configFilePath;
      const tsInternals = createTsInternals(ts);
      const errors: Array<_ts.Diagnostic> = [];

      // Follow chain of "extends"
      while (true) {
        const result = ts.readConfigFile(pathToNextConfigInChain, readFile);