Node.js v4.1.1 Documentation

Assert#

Stability: 2 - Stable

This module is used for writing unit tests for your applications. You can access it with require('assert').

assert.fail(actual, expected, message, operator)#

Throws an exception that displays the values for actual and expected separated by the provided operator.

assert(value[, message]), assert.ok(value[, message])#

Tests if value is truthy. It is equivalent to assert.equal(true, !!value, message).

assert.equal(actual, expected[, message])#

Tests shallow, coercive equality with the equal comparison operator ( == ).

assert.notEqual(actual, expected[, message])#

Tests shallow, coercive inequality with the not equal comparison operator ( != ).

assert.deepEqual(actual, expected[, message])#

Tests for deep equality. Primitive values are compared with the equal comparison operator ( == ). Doesn't take object prototypes into account.

assert.notDeepEqual(actual, expected[, message])#

Tests for any deep inequality. Opposite of assert.deepEqual.

assert.strictEqual(actual, expected[, message])#

Tests strict equality as determined by the strict equality operator ( === ).

assert.notStrictEqual(actual, expected[, message])#

Tests strict inequality as determined by the strict not equal operator ( !== ).

assert.deepStrictEqual(actual, expected[, message])#

Tests for deep equality. Primitive values are compared with the strict equality operator ( === ).

assert.notDeepStrictEqual(actual, expected[, message])#

Tests for deep inequality. Opposite of assert.deepStrictEqual.

assert.throws(block[, error][, message])#

Expects block to throw an error. error can be a constructor, RegExp, or validation function.

Validate instanceof using constructor: 

assert.throws(
  function() {
    throw new Error("Wrong value");
  },
  Error
);

Validate error message using RegExp: 

assert.throws(
  function() {
    throw new Error("Wrong value");
  },
  /value/
);

Custom error validation: 

assert.throws(
  function() {
    throw new Error("Wrong value");
  },
  function(err) {
    if ( (err instanceof Error) && /value/.test(err) ) {
      return true;
    }
  },
  "unexpected error"
);

assert.doesNotThrow(block[, message])#

Expects block not to throw an error. See assert.throws() for details.

assert.ifError(value)#

Throws value if value is truthy. This is useful when testing the error argument in callbacks.