find-test-caller/src/index.js

Finds the caller test function that called this library by inspecting the source file

'use strict'

'use strict'

const la = require('lazy-ass')
const is = require('check-more-types')
const falafel = require('falafel')
const crypto = require('crypto')
const debug = require('debug')('find-test-caller')
const path = require('path')

function isTestFunctionName (name) {
  return ['it', 'test'].includes(name)
}

function isTestFunction (node) {
  if (node.type === 'Identifier') {
    return isTestFunctionName(node.name)
  }
  if (node.type === 'MemberExpression') {
    return isTestFunctionName(node.object.name)
  }
}

function sha256 (string) {
  la(is.unemptyString(string), 'missing string to SHA', string)
  const hash = crypto.createHash('sha256')
  hash.update(string)
  return hash.digest('hex')
}

function shouldTranspile () {
  const exists = require('fs').existsSync
  if (!exists) {
    return false
  }
  return exists(path.join(process.cwd(), '.babelrc'))
}

function transpile (filename) {
  debug('transpiling %s', filename)
  const babel = require('babel-core')
  const {transformFileSync} = babel
  // trick to keep the line numbers same as original code
  const opts = {
    sourceMaps: false,
    retainLines: true
  }
  const {code} = transformFileSync(filename, opts)
  return code
}

function findInSource ({source, file, line}) {
  la(is.string(source), 'could not get source from', file, 'got', source)

  let foundSpecName, specSource, startLine
  const options = {
    locations: true,
    sourceType: 'module'
  }

  falafel(source, options, node => {
    if (foundSpecName) {
      // already found
      return
    }
    // nested IFs make debugging easier
    if (node.type === 'CallExpression') {
      if (isTestFunction(node.callee)) {
        if (node.loc.start.line < line &&
          node.loc.end.line > line) {
          debug('found test function around snapshot at line %d', line)

          if (node.arguments.length !== 2) {
            throw new Error('Cannot get test name for ' + node.source())
          }

          specSource = node.arguments[1].source()
          startLine = node.loc.start.line

          // TODO handle tests where just a single function argument was used
          // it(function testThis() {...})
          let specName

          const nameNode = node.arguments[0]
          if (nameNode.type === 'TemplateLiteral') {
            specName = nameNode.source().replace(/`/g, '')
            debug('template literal name "%s"', specName)
          } else if (nameNode.type === 'Literal') {
            specName = nameNode.value
            debug('regular string name "%s", specName')
          } else {
            // TODO handle single function
          }

          if (node.arguments.length === 2 &&
            node.arguments[1].type === 'FunctionExpression' &&
            node.arguments[1].id &&
            is.unemptyString(node.arguments[1].id.name)) {
            specName = node.arguments[1].id.name
            debug('callback function has a name "%s"', specName)
          }

          foundSpecName = specName

          if (!foundSpecName) {
            const hash = sha256(specSource)
            debug('using source hash %s for found spec in %s line %d',
              hash, file, line)
            foundSpecName = hash
          }
        }
      }
    }
  })
  return {
    specName: foundSpecName,
    specSource,
    startLine
  }
}

function findTestCaller ({fs, file, line}) {
  // TODO can be cached efficiently
  la(is.unemptyString(file), 'missing file', file)
  la(is.number(line), 'missing line number', line)

  const source = fs.readFileSync(file, 'utf8')

  let found
  try {
    found = findInSource({source, file, line})
  } catch (e) {
    debug('problem finding without transpiling %s %d', file, line)
    debug(e.message)
  }

  if (found) {
    return found
  }

  // HACK if it is just "async / await" problem, remove them!
  // could not get acorn / falafel to correctly parse "async / await" code
  if (source.includes('async') || source.includes('await')) {
    try {
      debug('found async keyword, trying to remove it')
      const removed = source.replace(/async|await/g, '     ')
      found = findInSource({source: removed, file, line})
    } catch (e) {
      debug('tried removing async / await %s %d', file, line)
      debug(e.message)
    }
  }
  if (found) {
    return found
  }

  // maybe we need transpiling?
  if (shouldTranspile()) {
    debug('should transpile and search')
    const transpiled = transpile(file)
    found = findInSource({source: transpiled, file, line})
    return found
  }
}

module.exports = findTestCaller