Function exists

src/toolbox/patching-tools.ts:12–29

(filename: string, findPattern: string | RegExp)

 * @return Boolean of success that findPattern was in file.
 */
export async function exists(filename: string, findPattern: string | RegExp): Promise<boolean> {
  // sanity check the filename
  if (!is(String, filename) || filesystem.isNotFile(filename)) return false

  // sanity check the findPattern
  const patternIsString = typeof findPattern === 'string'
  if (!(findPattern instanceof RegExp) && !patternIsString) return false

  // read from jetpack -- they guard against a lot of the edge
  // cases and return nil if problematic
  const contents = filesystem.read(filename)

  // only let the strings pass
  if (!is(String, contents)) return false

  // do the appropriate check
  return isPatternIncluded(contents, findPattern)
}

/**
 * Updates a text file or json config file. Async.