ts-essentials#assert TypeScript Examples

export function extractTsDocCommentsFromString(source: string): MethodComment[] {
  // @todo use TypeScript's parser to extract signatures and comments
  // We have a few bugs already — see skipped tests in extract.test.ts
  const DOC_COMMENT_REGEX = /\/\*\*([\s\S]*?)\*\/[\n\r]+([\s\S]*?)[{|\n\r]+/gm

  const methodComments: MethodComment[] = []

  let rawMethodComment = DOC_COMMENT_REGEX.exec(source)
  assert(rawMethodComment, `Couldn't find any block comments in source:\n\`${source}\``)
  while (rawMethodComment != null) {
    const comment = `/** ${rawMethodComment[1].trim()} */`
    let signature = removeGetterKeyword(rawMethodComment[2].trim())

    if (signature.endsWith(';')) signature = signature.slice(0, -1)

    methodComments.push({ signature, comment })

    rawMethodComment = DOC_COMMENT_REGEX.exec(source)
  }

  return methodComments
}

function abbreviateSignature(signature: string, project: TSProject): string {
  const isClassMethod = !signature.includes('function ')
  const sourceCode = isClassMethod ? `function ${signature} {}` : signature

  const sourceFile = project.createSourceFile('temp.ts', sourceCode, { overwrite: true })
  const functionDeclaration = sourceFile.getChildAtIndex(0).getChildAtIndex(0)
  assert(Node.isFunctionDeclaration(functionDeclaration))

  if (signature.includes('this:')) {
    functionDeclaration.getParameter('this')!.remove()
  }

  functionDeclaration.removeReturnType()

  let text = functionDeclaration.getText()

  if (isClassMethod) {
    text = text.slice('function '.length, -' {}'.length)
  }

  return text
}

constructor(private readonly _hooks: MochaHooks) {
    const self = this

    d('Installing beforeEach hook to get testInfo before each test')
    _hooks.beforeEach(function () {
      assert(this.currentTest, "Current test not set by mocha. This shouldn't happen.")
      assert(this.currentTest.file, "Current test file path not set by mocha. This shouldn't happen.")
      assert(this.currentTest.parent, "Current test has no parent set by mocha. This shouldn't happen.")

      self.testInfo = {
        suitName: makeSuiteName(this.currentTest.parent),
        testName: this.currentTest.title,
        testFilePath: this.currentTest.file,
      }
    })
  }

export function toThrow(control: Control<() => void>, expected: any) {
  assert(control.actual instanceof Function, 'Actual has to be a function to check if threw')

  let actualThrownValue: any | undefined
  let threwAnything = false
  try {
    control.actual()
  } catch (e) {
    threwAnything = true
    actualThrownValue = e
  }

  // we need special handling for this case otherwise we end up with really dummy error message
  if (!threwAnything) {
    return control.assert({
      success: false,
      reason: `Expected to throw but didn't`,
      negatedReason: '-',
    })
  }

  const actualFmt = formatCompact(actualThrownValue)
  const expectedFmt =
    expected instanceof AnythingMatcher
      ? 'anything'
      : expected instanceof ErrorMatcher
      ? expected.format()
      : formatCompact(expected)

  const reason = `Expected to throw ${expectedFmt} but threw ${actualFmt}`
  const negatedReason = `Expected not to throw ${expectedFmt} but threw ${actualFmt}`

  if (!isEqual(actualThrownValue, expected)) {
    control.assert({
      success: false,
      reason,
      negatedReason,
      actual: format(actualThrownValue, null),
      expected: format(expected, actualThrownValue),
    })
  } else {
    control.assert({
      success: true,
      reason,
      negatedReason,
    })
  }
}

function throwIfUndefined(val: any): any {
  assert(val !== undefined, 'val is undefined! Static config incorrect!')

  return val
}