# assert > A Node.js-compatible implementation of the core `assert` module - Source: https://titaniumsdk.com/docs/sdk/12.7.0/assert - Titanium SDK version: 12.7.0 - Kind: pseudo - Platforms: Android, iPhone, iPad, macOS - Since: Titanium SDK 8.1.0 Titanium provides a number of shims and ports of core Node.js module functionality. This module is intended to provide a Node-compatible port of the `assert` core module. More details on the Node.js API can be found in their [assert module documentation](https://nodejs.org/api/assert.html) **Note:** The `assert` module can also be invoked as a function and is equivalent to calling the [assert.ok](https://titaniumsdk.com/docs/sdk/assert.md#ok) method: ``` javascript const assert = require('assert'); assert(value, 'message'); // equivalent to assert.ok(value, 'message') ``` ## Properties ### AssertionError - Type: assert.AssertionError - Platforms: Android, iPhone, iPad, macOS extension of `Error` ### strict - Type: assert.strict - Platforms: Android, iPhone, iPad, macOS an alias of `assert` that enforces strict version of comparison methods ## Methods ### deepEqual - Platforms: Android, iPhone, iPad, macOS Tests for deep equality between the `actual` and `expected` parameters. Consider using `assert.deepStrictEqual()` instead. `assert.deepEqual()` can have surprising results. Parameters: - `actual` (any): The actual value - `expected` (any): The expected value - `message` (String | Error, optional): error message ### deepStrictEqual - Platforms: Android, iPhone, iPad, macOS Tests for deep equality between the `actual` and `expected` parameters. "Deep" equality means that the enumerable "own" properties of child objects are recursively evaluated also by the following rules. Parameters: - `actual` (any): The actual value - `expected` (any): The expected value - `message` (String | Error, optional): error message ### doesNotReject - Platforms: Android, iPhone, iPad, macOS Awaits the `asyncFn` promise or, if `asyncFn` is a function, immediately calls the function and awaits the returned promise to complete. It will then check that the promise is not rejected. If `asyncFn` is a function and it throws an error synchronously, `assert.doesNotReject()` will return a rejected `Promise` with that error. If the function does not return a promise, `assert.doesNotReject()` will return a rejected `Promise` with an `ERR_INVALID_RETURN_VALUE` error. In both cases the error handler is skipped. Using `assert.doesNotReject()` is actually not useful because there is little benefit in catching a rejection and then rejecting it again. Instead, consider adding a comment next to the specific code path that should not reject and keep error messages as expressive as possible. If specified, `error` can be a `Class`, `RegExp` or a validation function. See `assert.throws()` for more details. Besides the async nature to await the completion behaves identically to `assert.doesNotThrow()`. Parameters: - `asyncFn` (Function | Promise): function to invoke - `error` (RegExp | Function, optional): The expected `Error` type (class or name) - `message` (String, optional): error message ### doesNotThrow - Platforms: Android, iPhone, iPad, macOS Asserts that the function `fn` does not throw an `error`. Using `assert.doesNotThrow()` is actually not useful because there is no benefit in catching an error and then rethrowing it. Instead, consider adding a comment next to the specific code path that should not throw and keep error messages as expressive as possible. When `assert.doesNotThrow()` is called, it will immediately call the `fn` function. If an error is thrown and it is the same type as that specified by the `error` parameter, then an `AssertionError` is thrown. If the error is of a different type, or if the error parameter is undefined, the error is propagated back to the caller. If specified, `error` can be a Class, RegExp or a validation function. See `assert.throws()` for more details. Parameters: - `fn` (Function): function to invoke - `error` (RegExp | Function, optional): The expected `Error` type (class or name) - `message` (String, optional): error message ### equal - Platforms: Android, iPhone, iPad, macOS Tests shallow, coercive equality between the actual and expected parameters using the Abstract Equality Comparison (`==`). `NaN` is special handled and treated as being identical in case both sides are `NaN`. Parameters: - `actual` (any): The actual value - `expected` (any): The expected value - `message` (String | Error, optional): error message ### fail - Platforms: Android, iPhone, iPad, macOS Throws an `AssertionError` with the provided error message or a default error message. If the `message` parameter is an instance of an `Error` then it will be thrown instead of the `AssertionError`. Parameters: - `message` (String | Error, optional): error message Default: `Failed`. ### ifError - Platforms: Android, iPhone, iPad, macOS Throws `value` if `value` is not `undefined` or `null`. This is useful when testing the error argument in callbacks. The stack trace contains all frames from the error passed to `ifError()` including the potential new frames for `ifError()` itself. Parameters: - `value` (any): potentially thrown value/object ### notDeepEqual - Platforms: Android, iPhone, iPad, macOS Tests for any deep inequality. Opposite of `assert.deepEqual()`. Parameters: - `actual` (any): The actual value - `expected` (any): The expected value - `message` (String | Error, optional): error message ### notDeepStrictEqual - Platforms: Android, iPhone, iPad, macOS Tests for deep strict inequality. Opposite of `assert.deepStrictEqual()`. Parameters: - `actual` (any): The actual value - `expected` (any): The expected value - `message` (String | Error, optional): error message ### notEqual - Platforms: Android, iPhone, iPad, macOS Tests shallow, coercive inequality with the Abstract Equality Comparison (`!=`). `NaN` is special handled and treated as being identical in case both sides are `NaN`. Parameters: - `actual` (any): The actual value - `expected` (any): The expected value - `message` (String | Error, optional): error message ### notStrictEqual - Platforms: Android, iPhone, iPad, macOS Tests strict inequality between the actual and expected parameters as determined by the [SameValue Comparison](https://tc39.github.io/ecma262/#sec-samevalue). Parameters: - `actual` (any): The actual value - `expected` (any): The expected value - `message` (String | Error, optional): error message ### ok - Platforms: Android, iPhone, iPad, macOS Tests if `value` is truthy. It is equivalent to `assert.equal(!!value, true, message)`. If `value` is not truthy, an `AssertionError` is thrown with a message property set equal to the value of the `message` parameter. If the `message` parameter is `undefined`, a default error message is assigned. If the `message` parameter is an instance of an `Error` then it will be thrown instead of the `AssertionError`. If no arguments are passed in at all message will be set to the string: `'No value argument passed to \`assert.ok()\`'`. Parameters: - `value` (any): The input that is checked for being truthy. - `message` (String | Error, optional): error message ### rejects - Platforms: Android, iPhone, iPad, macOS Awaits the `asyncFn` promise or, if `asyncFn` is a function, immediately calls the function and awaits the returned promise to complete. It will then check that the promise is rejected. If `asyncFn` is a function and it throws an error synchronously, `assert.rejects()` will return a rejected `Promise` with that error. If the function does not return a promise, `assert.rejects()` will return a rejected `Promise` with an `ERR_INVALID_RETURN_VALUE` error. In both cases the error handler is skipped. Besides the async nature to await the completion behaves identically to `assert.throws()`. If specified, `error` can be a `Class`, `RegExp`, a validation function, an object where each property will be tested for, or an instance of error where each property will be tested for including the non-enumerable `message` and `name` properties. If specified, `message` will be the message provided by the `AssertionError` if the `asyncFn` fails to reject. Parameters: - `asyncFn` (Function | Promise): function to invoke - `error` (RegExp | Function | Object | Error, optional): The expected `Error` type (class or name) - `message` (String, optional): error message ### strictEqual - Platforms: Android, iPhone, iPad, macOS Tests strict equality between the actual and expected parameters as determined by the [SameValue Comparison](https://tc39.github.io/ecma262/#sec-samevalue). Parameters: - `actual` (any): The actual value - `expected` (any): The expected value - `message` (String | Error, optional): error message ### throws - Platforms: Android, iPhone, iPad, macOS Expects the function `fn` to throw an error. If specified, `error` can be a `Class`, `RegExp`, a validation function, a validation object where each property will be tested for strict deep equality, or an instance of error where each property will be tested for strict deep equality including the non-enumerable `message` and `name` properties. When using an object, it is also possible to use a regular expression, when validating against a string property. See below for examples. If specified, `message` will be appended to the message provided by the AssertionError if the fn call fails to throw or in case the error validation fails. Parameters: - `fn` (Function): function to invoke - `error` (RegExp | Function, optional): The expected `Error` type (class or name) - `message` (String, optional): error message --- - This corpus documents Titanium SDK 13.4.1. Anything here that does not name a version describes 13.4.1. - Titanium is maintained by TiDev. The Appcelerator toolchain is retired: there is no `appc` CLI, no Appcelerator Studio and no hosted build service. The supported CLI is `titanium` on npm, invoked as `ti`.