Function generateCodeFrame

packages/vitest/src/node/printError.ts:435–502

(
  source: string,
  indent = 0,
  loc: { line: number; column: number } | number,
  range = 2,
)

}

export function generateCodeFrame(
  source: string,
  indent = 0,
  loc: { line: number; column: number } | number,
  range = 2,
): string {
  const start
    = typeof loc === 'object'
      ? positionToOffset(source, loc.line, loc.column)
      : loc
  const end = start
  const lines = source.split(lineSplitRE)
  const nl = /\r\n/.test(source) ? 2 : 1
  let count = 0
  let res: string[] = []

  const columns = process.stdout?.columns || 80

  for (let i = 0; i < lines.length; i++) {
    count += lines[i].length + nl
    if (count >= start) {
      for (let j = i - range; j <= i + range || end > count; j++) {
        if (j < 0 || j >= lines.length) {
          continue
        }

        const lineLength = lines[j].length
        const strippedContent = stripVTControlCharacters(lines[j])

        if (strippedContent.startsWith('//# sourceMappingURL')) {
          continue
        }

        // too long, maybe it's a minified file, skip for codeframe
        if (strippedContent.length > 200) {
          return ''
        }

        const truncatedLine = truncateString(lines[j].replace(/\t/g, ' '), columns - 5 - indent).trimEnd()
        res.push(lineNo(j + 1) + (truncatedLine ? ' ' + truncatedLine : truncatedLine))

        if (j === i) {
          // push underline
          const pad = start - (count - lineLength) + (nl - 1)
          const length = Math.max(
            1,
            end > count ? lineLength - pad : end - start,
          )
          res.push(lineNo() + ' '.repeat(pad + 1) + c.red('^'.repeat(length)))
        }
        else if (j > i) {
          if (end > count) {
            const length = Math.max(1, Math.min(end - count, lineLength))
            res.push(lineNo() + ' ' + c.red('^'.repeat(length)))
          }
          count += lineLength + 1
        }
      }