assert.js

// Originally from narwhal.js (http://narwhaljs.org)
// Copyright (c) 2009 Thomas Robinson <280north.com>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the 'Software'), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
// ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

'use strict';

const { isDeepEqual, isDeepStrictEqual } =
  require('internal/util/comparisons');
const errors = require('internal/errors');
const { inspect } = require('util');

// The assert module provides functions that throw
// AssertionError's when particular conditions are not met. The
// assert module must conform to the following interface.

const assert = module.exports = ok;

// All of the following functions must throw an AssertionError
// when a corresponding condition is not met, with a message that
// may be undefined if not provided. All assertion methods provide
// both the actual and expected values to the assertion error for
// display purposes.

function innerFail(obj) {
  if (obj.message instanceof Error) throw obj.message;

  throw new errors.AssertionError(obj);
}

function fail(actual, expected, message, operator, stackStartFn) {
  const argsLen = arguments.length;

  if (argsLen === 0) {
    message = 'Failed';
  } else if (argsLen === 1) {
    message = actual;
    actual = undefined;
  } else if (argsLen === 2) {
    operator = '!=';
  }

  innerFail({
    actual,
    expected,
    message,
    operator,
    stackStartFn: stackStartFn || fail
  });
}

assert.fail = fail;

// The AssertionError is defined in internal/error.
// new assert.AssertionError({ message: message,
//                             actual: actual,
//                             expected: expected });
assert.AssertionError = errors.AssertionError;


// Pure assertion tests whether a value is truthy, as determined
// by !!value.
function ok(value, message) {
  if (!value) {
    innerFail({
      actual: value,
      expected: true,
      message,
      operator: '==',
      stackStartFn: ok
    });
  }
}
assert.ok = ok;

// The equality assertion tests shallow, coercive equality with ==.
/* eslint-disable no-restricted-properties */
assert.equal = function equal(actual, expected, message) {
  // eslint-disable-next-line eqeqeq
  if (actual != expected) {
    innerFail({
      actual,
      expected,
      message,
      operator: '==',
      stackStartFn: equal
    });
  }
};

// The non-equality assertion tests for whether two objects are not
// equal with !=.
assert.notEqual = function notEqual(actual, expected, message) {
  // eslint-disable-next-line eqeqeq
  if (actual == expected) {
    innerFail({
      actual,
      expected,
      message,
      operator: '!=',
      stackStartFn: notEqual
    });
  }
};

// The equivalence assertion tests a deep equality relation.
assert.deepEqual = function deepEqual(actual, expected, message) {
  if (!isDeepEqual(actual, expected)) {
    innerFail({
      actual,
      expected,
      message,
      operator: 'deepEqual',
      stackStartFn: deepEqual
    });
  }
};

// The non-equivalence assertion tests for any deep inequality.
assert.notDeepEqual = function notDeepEqual(actual, expected, message) {
  if (isDeepEqual(actual, expected)) {
    innerFail({
      actual,
      expected,
      message,
      operator: 'notDeepEqual',
      stackStartFn: notDeepEqual
    });
  }
};
/* eslint-enable */

assert.deepStrictEqual = function deepStrictEqual(actual, expected, message) {
  if (!isDeepStrictEqual(actual, expected)) {
    innerFail({
      actual,
      expected,
      message,
      operator: 'deepStrictEqual',
      stackStartFn: deepStrictEqual
    });
  }
};

assert.notDeepStrictEqual = notDeepStrictEqual;
function notDeepStrictEqual(actual, expected, message) {
  if (isDeepStrictEqual(actual, expected)) {
    innerFail({
      actual,
      expected,
      message,
      operator: 'notDeepStrictEqual',
      stackStartFn: notDeepStrictEqual
    });
  }
}

assert.strictEqual = function strictEqual(actual, expected, message) {
  if (!Object.is(actual, expected)) {
    innerFail({
      actual,
      expected,
      message,
      operator: 'strictEqual',
      stackStartFn: strictEqual
    });
  }
};

assert.notStrictEqual = function notStrictEqual(actual, expected, message) {
  if (Object.is(actual, expected)) {
    innerFail({
      actual,
      expected,
      message,
      operator: 'notStrictEqual',
      stackStartFn: notStrictEqual
    });
  }
};

function createMsg(msg, key, actual, expected) {
  if (msg)
    return msg;
  return `${key}: expected ${inspect(expected[key])}, ` +
    `not ${inspect(actual[key])}`;
}

function expectedException(actual, expected, msg) {
  if (typeof expected !== 'function') {
    if (expected instanceof RegExp)
      return expected.test(actual);
    // assert.doesNotThrow does not accept objects.
    if (arguments.length === 2) {
      throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'expected',
                                 ['Function', 'RegExp'], expected);
    }
    // The name and message could be non enumerable. Therefore test them
    // explicitly.
    if ('name' in expected) {
      assert.strictEqual(
        actual.name,
        expected.name,
        createMsg(msg, 'name', actual, expected));
    }
    if ('message' in expected) {
      assert.strictEqual(
        actual.message,
        expected.message,
        createMsg(msg, 'message', actual, expected));
    }
    const keys = Object.keys(expected);
    for (const key of keys) {
      assert.deepStrictEqual(
        actual[key],
        expected[key],
        createMsg(msg, key, actual, expected));
    }
    return true;
  }
  // Guard instanceof against arrow functions as they don't have a prototype.
  if (expected.prototype !== undefined && actual instanceof expected) {
    return true;
  }
  if (Error.isPrototypeOf(expected)) {
    return false;
  }
  return expected.call({}, actual) === true;
}

function getActual(block) {
  if (typeof block !== 'function') {
    throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'block', 'Function',
                               block);
  }
  try {
    block();
  } catch (e) {
    return e;
  }
}

// Expected to throw an error.
assert.throws = function throws(block, error, message) {
  const actual = getActual(block);

  if (typeof error === 'string') {
    if (arguments.length === 3)
      throw new errors.TypeError('ERR_INVALID_ARG_TYPE',
                                 'error',
                                 ['Function', 'RegExp'],
                                 error);

    message = error;
    error = null;
  }

  if (actual === undefined) {
    let details = '';
    if (error && error.name) {
      details += ` (${error.name})`;
    }
    details += message ? `: ${message}` : '.';
    innerFail({
      actual,
      expected: error,
      operator: 'throws',
      message: `Missing expected exception${details}`,
      stackStartFn: throws
    });
  }
  if (error && expectedException(actual, error, message) === false) {
    throw actual;
  }
};

assert.doesNotThrow = function doesNotThrow(block, error, message) {
  const actual = getActual(block);
  if (actual === undefined)
    return;

  if (typeof error === 'string') {
    message = error;
    error = null;
  }

  if (!error || expectedException(actual, error)) {
    const details = message ? `: ${message}` : '.';
    innerFail({
      actual,
      expected: error,
      operator: 'doesNotThrow',
      message: `Got unwanted exception${details}\n${actual.message}`,
      stackStartFn: doesNotThrow
    });
  }
  throw actual;
};

assert.ifError = function ifError(err) { if (err) throw err; };

// Expose a strict only variant of assert
function strict(value, message) {
  if (!value) {
    innerFail({
      actual: value,
      expected: true,
      message,
      operator: '==',
      stackStartFn: strict
    });
  }
}
assert.strict = Object.assign(strict, assert, {
  equal: assert.strictEqual,
  deepEqual: assert.deepStrictEqual,
  notEqual: assert.notStrictEqual,
  notDeepEqual: assert.notDeepStrictEqual
});
assert.strict.strict = assert.strict;