Assert

The Assert plugin of Japa is built on top of Chai.js assert package. However, it is not an exact copy of chai, and therefore we recommend you to consult the API documented in this guide.

Suppose you have not configured the plugin during the initial setup. Then, you can install it from the npm registry as follows.

npm i -D @japa/assert@1.4.1

And register it as a plugin within the bin/test.js file.

import { assert } from '@japa/assert'
import { configure, processCliArgs } from '@japa/runner'

configure({
  ...processCliArgs(process.argv.slice(2)),
  ...{
    files: ['tests/**/*.spec.js'],
    plugins: [assert()]
  }
})

const { assert } = require('@japa/assert')
const { configure, processCliArgs } = require('@japa/runner')

configure({
  ...processCliArgs(process.argv.slice(2)),
  ...{
    files: ['tests/**/*.spec.js'],
    plugins: [assert()]
  }
})

Once done. You can access the assert property from the Test context as follows.

test('add two numbers', ({ assert }) => {
  assert.equal(2 + 2, 4)
})

Open API testing

Using this plugin, you can test HTTP responses against one or more open API schemas. Just make sure to register the path to schema files when using the plugin.

const config = {
  openApi: {
    schemas: [join(__dirname, '..', './api-schema.json')]
  }
}

configure({
  plugins: [
    assert(config) // 👈 register config
  ]
})

Once done, you can test response objects from axios, superagent, supertest, request, and light-my-request libraries using the following method.

test('get /users', async ({ assert }) => {
  const response = await supertest(baseUrl).get('/')
  assert.isValidApiResponse(response)
})

The response is validated as follows:

An error is raised if the request path is not documented in the API schema file.
An error is raised if the response status code is not documented in the API schema file.
An error is raised if the body properties are not the same as expected by the schema. Use the required array to validate required response properties.
The response status code is used to find the body schema for validation.
Response headers are also validated against the expected headers mentioned inside the API schema file.

assert

Assert an expression to be truthy. Then, optionally define the error message.

assert(isTrue(foo))
assert(foo === 'bar')
assert(age > 18, 'Not allowed to enter the club')

equal

Assert two values are equal but not strictly. The comparison is the same as foo == bar.

See strictEqual for strict equality.
See deepEqual for comparing objects and arrays.

assert.equal(3, 3) // passes
assert.equal(3, '3') // passes
assert.equal(Symbol.for('foo'), Symbol.for('foo')) // passes

Name	Type
`actual`	`any`
`expected`	`any`
`message?`	`string`

notEqual

Assert two values are not equal. The comparison is the same as foo != bar.

See notStrictEqual for strict inequality.
See notDeepEqual for comparing objects and arrays.

assert.notEqual(3, 2) // passes
assert.notEqual(3, '2') // passes
assert.notEqual(Symbol.for('foo'), Symbol.for('bar')) // passes

Name	Type
`actual`	`any`
`expected`	`any`
`message?`	`string`

strictEqual

Assert two values are strictly equal. The comparison is same as foo === bar.

See equal for non-strict equality.
See deepEqual for comparing objects and arrays.

assert.strictEqual(3, 3) // passes
assert.strictEqual(3, '3') // fails
assert.strictEqual(Symbol.for('foo'), Symbol.for('foo')) // passes

Name	Type
`actual`	`any`
`expected`	`any`
`message?`	`string`

notStrictEqual

Assert two values are not strictly equal. The comparison is same as foo !== bar.

assert.notStrictEqual(3, 2) // passes
assert.notStrictEqual(3, '2') // fails
assert.notStrictEqual(Symbol.for('foo'), Symbol.for('bar')) // passes

Name	Type
`actual`	`any`
`expected`	`any`
`message?`	`string`

deepEqual

Assert two values are deeply equal. The order of items in an array should be the same for the assertion to pass.

assert.deepEqual({ a: 1, b: 2 }, { a: 1, b: 2 }) // passes
assert.deepEqual({ b: 2, a: 1 }, { a: 1, b: 2 }) // passes
assert.deepEqual([1, 2], [1, 2]) // passes
assert.deepEqual([1, 2], [2, 1]) // fails
assert.deepEqual(/a/, /a/) // passes
assert.deepEqual(
  new Date('2020 01 22'),
  new Date('2020 01 22')
) // passes

Name	Type
`actual`	`any`
`expected`	`any`
`message?`	`string`

notDeepEqual

Assert two values are not deeply equal.

assert.notDeepEqual({ a: 1, b: 2 }, { a: 1, b: '2' }) // passes
assert.notDeepEqual([1, 2], [2, 1]) // passes
assert.notDeepEqual(
  new Date('2020 01 22'),
  new Date('2020 01 23')
) // passes

Name	Type
`actual`	`any`
`expected`	`any`
`message?`	`string`

rejects

Assert the function to reject the promise. Optionally, you can assert the rejection is from a particular class or has a specific message.

await assert.rejects(() => {
  throw new Error('')
}) // passes

await assert.rejects(() => {
  async () => throw new HttpError('Resource not found')
}, HttpError) // passes

await assert.rejects(() => {
  async () => throw new HttpError('Resource not found')
}, 'Resource not found') // passes

Name	Type
`fn`	() => `void`
`message?`	`string`

Name	Type
`fn`	() => `void` \| `Promise`<`void`>
`errType`	`RegExp` \| `ErrorConstructor`
`message?`	`string`

Name	Type
`fn`	() => `void` \| `Promise`<`void`>
`constructor`	`ErrorConstructor`
`regExp`	`string` \| `RegExp`
`message?`	`string`

doesNotRejects

Assert the function does not reject the promise. Optionally, you can assert the rejection is not from a specific class or have a particular message.

await assert.doesNotRejects(async () => {
  throw new Error('foo')
}, HttpError) // passes: Error !== HttpError

await assert.doesNotRejects(
  async () => {
    throw new HttpError('Resource not found')
  }, 
  'Server not available'
) // passes: Resource not found !== Server not available

await assert.doesNotRejects(async () => {
  return 'foo'
}) // passes

Name	Type
`fn`	() => `void`
`message?`	`string`

Name	Type
`fn`	() => `void` \| `Promise`<`void`>
`errType`	`RegExp` \| `ErrorConstructor`
`message?`	`string`

Name	Type
`fn`	() => `void` \| `Promise`<`void`>
`constructor`	`ErrorConstructor`
`regExp`	`string` \| `RegExp`
`message?`	`string`

throws

Expect the function to throw an exception. Optionally, you can assert for the exception class or message.

See rejects for async function calls.

function foo() { throw new Error('blow up') }

assert.throws(foo) // passes
assert.throws(foo, Error) // passes
assert.throws(foo, 'blow up') // passes
assert.throws(foo, 'failed') // fails

Name	Type
`fn`	() => `void`
`message?`	`string`

Name	Type
`fn`	() => `void`
`errType`	`RegExp` \| `ErrorConstructor`
`message?`	`string`

Name	Type
`fn`	() => `void`
`constructor`	`ErrorConstructor`
`regExp`	`string` \| `RegExp`
`message?`	`string`

doesNotThrows

Expect the function not to throw an exception. Optionally, you can assert the exception is not from a particular class or has a specific message.

See doesNotRejects for async function calls.

function foo() { throw new Error('blow up') }

assert.doesNotThrows(foo) // fails
assert.doesNotThrows(foo, 'failed') // passes
assert.doesNotThrows(() => {}) // passes

Name	Type
`fn`	() => `void`
`message?`	`string`

Name	Type
`fn`	() => `void`
`regExp`	`RegExp`

Name	Type
`fn`	() => `void`
`constructor`	`ErrorConstructor`
`message?`	`string`

Name	Type
`fn`	() => `void`
`constructor`	`ErrorConstructor`
`regExp`	`string` \| `RegExp`
`message?`	`string`

lengthOf

Assert the length of an array, map, or set to match the expected value

assert.lengthOf([1, 2, 3], 3)
assert.lengthOf(new Map([[1],[2]]), 2)
assert.lengthOf('hello world', 11)

Name	Type
`object`	`Array`
`length`	`number`
`message?`	`string`

empty/isEmpty

Assert value to be empty.

assert.empty([]) // passes
assert.empty('') // passes

assert.isEmpty([]) // passes
assert.isEmpty('') // passes

Name	Type
`object`	`any`
`message?`	`string`

notEmpty/isNotEmpty

Assert value to not be empty.

assert.notEmpty([1, 2]) // passes
assert.notEmpty({ foo: 'bar' }) // passes
assert.notEmpty('hello') // passes

Name	Type
`object`	`any`
`message?`	`string`

exists

Asserts the value is not null or undefined.

assert.exists(false) // passes
assert.exists(0) // passes
assert.exists('') // passes
assert.exists(null) // fails
assert.exists(undefined) // fails

Name	Type
`value`	`any`
`message?`	`string`

notExists

Asserts the value is null or undefined.

assert.notExists(null) // passes
assert.notExists(undefined) // passes
assert.notExists('') // fails
assert.notExists(false) // fails
assert.notExists(0) // fails

Name	Type
`value`	`any`
`message?`	`string`

include

Assert the collection includes an item. Works for strings, arrays, and objects.

See deepInclude for deep comparsion.

assert.include(
  { id: 1, name: 'virk' },
  { name: 'virk' }
) // passes

assert.include([1, 2, 3], 2) // passes
assert.include('hello world', 'hello') // passes

Name	Type
`haystack`	`any`
`needle`	`Partial<haystack>`
`message?`	`string`

notInclude

Assert the collection NOT to include an item. Works for strings, arrays and objects.

See notDeepInclude for nested object properties.

assert.include(
  { id: 1, name: 'virk' },
  { name: 'virk' }
) // passes

assert.include([1, 2, 3], 2) // passes
assert.include('hello world', 'hello') // passes

Name	Type
`haystack`	`any`
`needle`	`Partial<haystack>`
`message?`	`string`

deepInclude

Assert the collection includes an item. Works for strings, arrays, and objects.

assert.deepInclude(
  { foo: { a: 1 }, bar: { b: 2 } },
  { foo: { a: 1 } }
) // passes

assert.deepInclude([1, [2], 3], [2]) // passes

Name	Type
`haystack`	`any`
`needle`	`Partial<haystack>`
`message?`	`string`

notDeepInclude

Assert the collection NOT to include an item. Works for strings, arrays, and objects.

assert.notDeepInclude(
  { foo: { a: 1 }, bar: { b: 2 } },
  { foo: { a: 4 } }
) // passes

assert.deepInclude([1, [2], 3], [20]) // passes

Name	Type
`haystack`	`any`
`needle`	`Partial<haystack>`
`message?`	`string`

instanceOf

Assert value to be an instance of the expected class.

assert.instanceOf(new User(), User) // passes
assert.instanceOf(new User(), Function) // fails

class User extends BaseUser {}
assert.instanceOf(new User(), BaseUser) // passes

Name	Type
`value`	`any`
`constructor`	`Function`
`message?`	`string`

notInstanceOf

Assert value NOT to be an instance of the expected class.

assert.notInstanceOf(new User(), Function) // passes
assert.notInstanceOf(new User(), User) // fails

Name	Type
`value`	`any`
`constructor`	`Function`
`message?`	`string`

ok/isOk

Assert the value is truthy.

assert.ok({ hello: 'world' }) // passes
assert.ok(null) // fails

assert.isOk({ hello: 'world' }) // passes
assert.isOk(null) // fails

Name	Type
`value`	`any`
`message?`	`string`

notOk/isNotOk

Assert the value is falsy.

assert.notOk({ hello: 'world' }) // fails
assert.notOk(null) // passes

assert.isNotOk({ hello: 'world' }) // fails
assert.isNotOk(null) // passes

Name	Type
`value`	`any`
`message?`	`string`

properties

Assert the object has all of the expected properties.

assert.properties(
  { username: 'virk', age: 22, id: 1 },
  ['id', 'age']
) // passes

assert.properties(
  { username: 'virk', id: 1 },
  ['id', 'age']
) // fails: "age" is missing

Name	Type
`object`	`any`
`keys`	`string[]`
`message?`	`string`

notAllProperties

Assert the object not to have all of the mentioned properties.

assert.notAllProperties(
  { id: 1, name: 'foo' },
  ['id', 'name', 'email']
) // passes

Name	Type
`object`	`any`
`keys`	`string[]
`message?`	`string`

onlyProperties

Assert the object has only the expected properties. The assertion will fail when the object contains properties not mentioned in the keys array.

assert.onlyProperties(
  { username: 'virk', age: 22, id: 1 },
  ['id', 'name', 'age']
) // passes

assert.onlyProperties(
  { username: 'virk', age: 22, id: 1 },
  ['id', 'name']
) // fails

Name	Type
`object`	`any`
`keys`	`string[]`
`message?`	`string`

notAnyProperties

Assert the object not to have any of the mentioned properties.

assert.notAnyProperties(
  { id: 1, name: 'foo' },
  ['email', 'age']
) // passes

assert.notAnyProperties(
  { id: 1, name: 'foo' },
  ['email', 'id']
) // fails

Name	Type
`object`	`any`
`keys`	`string[]
`message?`	`string`

property

Assert an object to contain a property.

assert.property(
  { id: 1, username: 'virk' },
  'id'
) // passes

Name	Type
`object`	`any`
`property`	`string`
`message?`	`string`

notProperty

Assert an object NOT to contain a property.

assert.notProperty(
  { id: 1, username: 'virk' },
  'email'
) // passes

Name	Type
`object`	`any`
`property`	`string`
`message?`	`string`

propertyVal

Assert an object property to match the expected value.

Use deepPropertyVal for deep comparing the value.

assert.propertyVal(
  { id: 1, username: 'virk' },
  'id',
  1
) // passes

assert.propertyVal(
  { user: { id: 1 } },
  'user',
  { id: 1 }
) // fails

Name	Type
`object`	`any`
`property`	`string`
`value`	`any`
`message?`	`string`

notPropertyVal

Assert an object property NOT to match the expected value.

Use notDeepPropertyVal for deep comparing the value.

assert.notPropertyVal(
  { id: 1, username: 'virk' },
  'id',
  22
) // passes

Name	Type
`object`	`any`
`property`	`string`
`value`	`any`
`message?`	`string`

deepPropertyVal

Assert an object property to match the expected value deeply.

assert.deepPropertyVal(
  { user: { id: 1 } },
  'user',
  { id: 1 }
) // passes

Name	Type
`object`	`any`
`property`	`string`
`value`	`any`
`message?`	`string`

notDeepPropertyVal

Assert an object property NOT deeply to match the expected value

assert.notDeepPropertyVal(
  { user: { id: 1 } },
  'user',
  { email: 'foo@bar.com' }
) // passes

Name	Type
`actual`	`any`
`property`	`string`
`value`	`any`
`message?`	`string`

includeMembers

Assert the expected array is a subset of a given collection. The values comparison is the same as the assert.equal method.

Use includeDeepMembers for deep comparsion.

assert.includeMembers([1, 2, 4, 5], [1, 2]) // passes
assert.includeMembers([1, 2, 4, 5], [1, 3]) // fails

Name	Type
`superset`	`any[]`
`subset`	`any[]`
`message?`	`string`

notIncludeMembers

Assert the expected array is NOT a subset of a given collection. The values comparison is the same as the assert.notEqual method.

Use notIncludeDeepMembers for deep comparsion.

assert.notIncludeMembers([1, 2, 4, 5], [1, 3]) // passes
assert.notIncludeMembers([1, 2, 4, 5], [1, 2]) // fails

Name	Type
`superset`	`any[]`
`subset`	`any[]`
`message?`	`string`

includeDeepMembers

Assert the expected array is a subset of a given array. The values comparison is the same as the assert.deepEqual method.

assert.includeDeepMembers(
  [{ id: 1 }, { id: 2 }],
  [{ id: 2 }]
) // passes

assert.includeDeepMembers(
  [{ id: 1 }, { id: 2 }],
  [{ id: 3 }]
) // fails

Name	Type
`superset`	`any[]`
`subset`	`any[]`
`message?`	`string`

notIncludeDeepMembers

Assert the expected array is NOT a subset of a given array. The values comparison is the same as the assert.notDeepEqual method.

assert.notIncludeDeepMembers(
  [{ id: 1 }, { id: 2 }],
  [{ id: 3 }]
) // passes

assert.notIncludeDeepMembers(
  [{ id: 1 }, { id: 2 }],
  [{ id: 2 }]
) // fails

Name	Type
`superset`	`any[]`
`subset`	`any[]`
`message?`	`string`

includeOrderedMembers

Assert the expected array is a subset of a given array and in the same order. The values comparison is the same as the assert.equal method.

Use includeDeepOrderedMembers for deep comparsion.

assert.includeOrderedMembers(
  [1, 2, 4, 5],
  [1, 2, 4]
) // passes

assert.includeOrderedMembers(
  [1, 2, 4, 5],
  [1, 4, 2]
) // fails

assert.includeOrderedMembers(
  [1, 2, 4, 5],
  [1, 2, 5]
) // fails

Name	Type
`superset`	`any[]`
`subset`	`any[]`
`message?`	`string`

notIncludeOrderedMembers

Assert the expected array is either not a subset of a given array or is not in the same order. The values comparison is the same as the assert.notEqual method.

Use notIncludeDeepOrderedMembers for deep comparsion.


assert.notIncludeOrderedMembers(
  [1, 2, 4, 5],
  [1, 4, 2]
) // passes

assert.notIncludeOrderedMembers(
  [1, 2, 4, 5],
  [1, 2, 5]
) // passes

assert.notIncludeOrderedMembers(
  [1, 2, 4, 5],
  [1, 2, 4]
) // fails

Name	Type
`superset`	`any[]`
`subset`	`any[]`
`message?`	`string`

includeDeepOrderedMembers

Assert the expected array is a subset of a given array and in the same order. The values comparison is the same as the assert.deepEqual method.

assert.includeDeepOrderedMembers(
  [{ id: 1 }, { id: 2 }, { id: 4 }],
  [{ id: 1 }, { id: 2 }]
) // passes

assert.includeDeepOrderedMembers(
  [{ id: 1 }, { id: 2 }, { id: 4 }],
  [{ id: 1 }, { id: 4 }]
) // fails

assert.includeDeepOrderedMembers(
  [{ id: 1 }, { id: 2 }, { id: 4 }],
  [{ id: 1 }, { id: 4 }, { id: 2 }]
) // fails

Name	Type
`superset`	`any[]`
`subset`	`any[]`
`message?`	`string`

notIncludeDeepOrderedMembers

Assert the expected array is either not a subset of a given array or is not in the same order. The values comparison is the same as the assert.notDeepEqual method.

assert.notIncludeDeepOrderedMembers(
  [{ id: 1 }, { id: 2 }, { id: 4 }],
  [{ id: 1 }, { id: 4 }]
) // passes

assert.notIncludeDeepOrderedMembers(
  [{ id: 1 }, { id: 2 }, { id: 4 }],
  [{ id: 1 }, { id: 4 }, { id: 2 }]
) // passes

assert.notIncludeDeepOrderedMembers(
  [{ id: 1 }, { id: 2 }, { id: 4 }],
  [{ id: 1 }, { id: 2 }]
) // fails

Name	Type
`superset`	`any[]`
`subset`	`any[]`
`message?`	`string`

sameMembers

Assert two arrays to have the same members. The values comparison is the same as the assert.equal method.

Use sameDeepMembers for deep comparison.

assert.sameMembers(
  [1, 2, 3],
  [1, 2, 3]
) // passes

assert.sameMembers(
  [1, { id: 1 }, 3],
  [1, { id: 1 }, 3]
) // fails

Name	Type
`set1`	`any[]`
`set2`	`any[]`
`message?`	`string`

notSameMembers

Assert two arrays NOT to have the same members. The values comparison is the same as the assert.notEqual method.

Use notSameDeepMembers for deep comparison.

assert.notSameMembers(
  [1, { id: 1 }, 3],
  [1, { id: 1 }, 3]
) // passes

assert.notSameMembers(
  [1, 2, 3],
  [1, 2, 3]
) // fails

Name	Type
`set1`	`any[]`
`set2`	`any[]`
`message?`	`string`

sameDeepMembers

Assert two arrays to have the same members.

assert.sameDeepMembers(
  [1, 2, 3],
  [1, 2, 3]
) // passes

assert.sameDeepMembers(
  [1, { id: 1 }, 3],
  [1, { id: 1 }, 3]
) // passes

Name	Type
`set1`	`any[]`
`set2`	`any[]`
`message?`	`string`

notSameDeepMembers

Assert two arrays NOT to have the same members.

assert.notSameDeepMembers(
  [1, { id: 1 }, 3],
  [1, { id: 2 }, 3]
) // passes

Name	Type
`set1`	`any[]`
`set2`	`any[]`
`message?`	`string`

sameOrderedMembers

Expect two arrays to have the same members and in the same order. The values comparison is the same as the assert.equal method.

Use sameDeepOrderedMembers for deep comparison.

assert.sameOrderedMembers(
  [1, 2, 3],
  [1, 2, 3]
) // passes

assert.sameOrderedMembers(
  [1, 3, 2],
  [1, 2, 3]
) // fails

Name	Type
`set1`	`any[]`
`set2`	`any[]`
`message?`	`string`

notSameOrderedMembers

Expect two arrays to either have different members or be in a different order. The values comparison is the same as the assert.notEqual method.

Use notSameDeepOrderedMembers for deep comparison.

assert.notSameOrderedMembers(
  [1, 2, 3],
  [1, 2, 3]
) // passes

assert.notSameOrderedMembers(
  [1, 3, 2],
  [1, 2, 3]
) // fails

Name	Type
`set1`	`any[]`
`set2`	`any[]`
`message?`	`string`

sameDeepOrderedMembers

Expect two arrays to have the same members and in the same order. The values comparison is the same as the assert.deepEqual method.

assert.sameDeepOrderedMembers(
  [1, { id: 1 }, { name: 'virk' }],
  [1, { id: 1 }, { name: 'virk' }]
) // passes

assert.sameDeepOrderedMembers(
  [1, { id: 1 }, { name: 'virk' }],
  [1, { name: 'virk' }, { id: 1 }]
) // fails

Name	Type
`set1`	`any[]`
`set2`	`any[]`
`message?`	`string`

notSameDeepOrderedMembers

Expect two arrays to either have different members or be in a different order. The values comparison is the same as the assert.notDeepEqual method.

assert.notSameDeepOrderedMembers(
  [1, { id: 1 }, { name: 'virk' }],
  [1, { name: 'virk' }, { id: 1 }]
) // passes

assert.notSameDeepOrderedMembers(
  [1, { id: 1 }, { name: 'virk' }],
  [1, { id: 1 }, { name: 'virk' }]
) // fails

Name	Type
`set1`	`any[]`
`set2`	`any[]`
`message?`	`string`

containsSubset

Assert an array or an object to contain a subset of the expected value. Useful for testing API responses.

assert.containsSubset(
  { id: 1, created_at: Date },
  { id: 1 }
) // passes

assert.containsSubset(
  [
    { id: 1, created_at: Date },
    { id: 2, created_at: Date }
  ],
  [{ id: 1 }, { id: 2 }]
) // passes

Name	Type
`haystack`	`any`
`needle`	`any`
`message?`	`string`

notContainsSubset

Assert an array or an object not to contain a subset of the expected value.

assert.notContainsSubset(
  { id: 1, created_at: Date },
  { email: 'foo@bar.com' }
) // passes

Name	Type
`haystack`	`any`
`needle`	`any`
`message?`	`string`

oneOf

Assert the value is available in the provided list. This method only works with literal values.

See containsSubset matching objects and arrays.

assert.oneOf('foo', ['foo', 'bar', 'baz']) // passes
assert.oneOf('foo', ['bar', 'baz']) // fails

Name	Type
`value`	`any`
`collection`	`any[]`
`message?`	`string`

sealed/isSealed

Assert the object is sealed.

assert.sealed(Object.seal({})) // passes
assert.sealed({}) // fails

assert.isSealed(Object.seal({})) // passes
assert.isSealed({}) // fails

Name	Type
`object`	`any`
`message?`	`string`

notSealed/isNotSealed

Assert the object is not sealed.

assert.notSealed({}) // passes
assert.notSealed(Object.seal({})) // fails

assert.isNotSealed({}) // passes
assert.isNotSealed(Object.seal({})) // fails

Name	Type
`object`	`any`
`message?`	`string`

isAbove

Assert if the actual value is above the expected value. Supports numbers, dates and luxon datetime object.

assert.isAbove(5, 2) // passes
assert.isAbove(new Date('2020 12 20'), new Date('2020 12 18')) // passes

Name	Type
`valueToCheck`	`Date`
`valueToBeAbove`	`Date`
`message?`	`string`

Name	Type
`valueToCheck`	`number`
`valueToBeAbove`	`number`
`message?`	`string`

isBelow

Assert if the actual value is below expected value. numbers, dates and luxon datetime object.

assert.isBelow(2, 5) // passes
assert.isBelow(new Date('2020 12 20'), new Date('2020 12 24')) // passes

Name	Type
`valueToCheck`	`Date`
`valueToBeBelow`	`Date`
`message?`	`string`

Name	Type
`valueToCheck`	`number`
`valueToBeBelow`	`number`
`message?`	`string`

isAtLeast

Assert if the actual value is above or the same as the expected value. Supports numbers, dates and luxon datetime object.

assert.isAtLeast(2, 2) // passes
assert.isAtLeast(new Date('2020 12 20'), new Date('2020 12 20')) // passes

Name	Type
`valueToCheck`	`Date`
`valueToBeAtLeast`	`Date`
`message?`	`string`

Name	Type
`valueToCheck`	`number`
`valueToBeAtLeast`	`number`
`message?`	`string`

isAtMost

Assert if the actual value is below or the same as the expected value. numbers, dates and luxon datetime object.

assert.isAtMost(2, 2) // passes
assert.isAtMost(new Date('2020 12 20'), new Date('2020 12 20')) // passes

Name	Type
`valueToCheck`	`Date`
`valueToBeAtMost`	`Date`
`message?`	`string`

Name	Type
`valueToCheck`	`number`
`valueToBeAtMost`	`number`
`message?`	`string`

match

Assert the value to match the given regular expression.

assert.match('foobar', /^foo/) // passes

Name	Type
`value`	`string`
`regexp`	`RegExp`
`message?`	`string`

notMatch

Assert the value NOT to match the given regular expression.

assert.notMatch('foobar', /^foo/) // fails

Name	Type
`expected`	`string`
`regexp`	`RegExp`
`message?`	`string`

typeOf

Assert the typeof value that matches the expected type.

assert.typeOf({ foo: 'bar' }, 'object') // passes
assert.typeOf(['admin'], 'array') // passes
assert.typeOf(new Date(), 'date') // passes

Name	Type
`value`	`any`
`type`	`string`
`message?`	`string`

notTypeOf

Assert the typeof value is not the same as the expected type.

assert.notTypeOf({ foo: 'bar' }, 'array') // passes
assert.notTypeOf(['admin'], 'string') // passes

Name	Type
`value`	`any`
`type`	`string`
`message?`	`string`

frozen/isFrozen

Assert the object is frozen.

assert.frozen(Object.freeze({})) // passes
assert.frozen({}) // fails

assert.isFrozen(Object.freeze({})) // passes
assert.isFrozen({}) // fails

Name	Type
`object`	`any`
`message?`	`string`

notFrozen/isNotFrozen

Assert the object is not frozen.

assert.notFrozen({}) // passes
assert.notFrozen(Object.freeze({})) // fails

assert.isNotFrozen({}) // passes
assert.isNotFrozen(Object.freeze({})) // fails

Name	Type
`object`	`any`
`message?`	`string`

isArray

Assert the value to be a valid array

assert.isArray([]) // passes
assert.isArray({}) // fails

Name	Type
`value`	`any`
`message?`	`string`

isNotArray

Assert the value not to be an array

assert.isNotArray([]) // fails
assert.isNotArray({}) // passes

Name	Type
`value`	`any`
`message?`	`string`

isBoolean

Assert the value is a boolean.

assert.isBoolean(true) // passes
assert.isBoolean(false) // passes
assert.isBoolean(1) // fails

Name	Type
`value`	`any`
`message?`	`string`

isNotBoolean

Assert the value is anything, but not a boolean.

assert.isNotBoolean(1) // passes
assert.isNotBoolean(false) // fails
assert.isNotBoolean(true) // fails

Name	Type
`value`	`any`
`message?`	`string`

isDefined

Asserts the value is anything, but not undefined.

assert.isDefined(undefined) // fails
assert.isDefined(0) // passes
assert.isDefined(false) // passes
assert.isDefined('') // passes
assert.isDefined(null) // passes

Name	Type
`value`	`any`
`message?`	`string`

isUndefined

Asserts the value is explicitly "undefined."

assert.isUndefined(undefined) // passes
assert.isUndefined(false) // fails
assert.isUndefined(0) // fails
assert.isUndefined('') // fails
assert.isUndefined(null) // fails

Name	Type
`value`	`any`
`message?`	`string`

isFalse

Assert the value is boolean (false)

assert.isFalse(false) // passes
assert.isFalse(true) // fails
assert.isFalse(0) // fails
assert.isFalse(null) // fails

Name	Type
`value`	`any`
`message?`	`string`

isNotFalse

Assert the value is anything but not false.

assert.isNotFalse(false) // fails
assert.isNotFalse(true) // passes
assert.isNotFalse(null) // passes
assert.isNotFalse(undefined) // passes

Name	Type
`value`	`any`
`message?`	`string`

isFinite

Assert the value to be a number and no NaN or Infinity

assert.isFinite(1) // passes
assert.isFinite(Infinity) // fails
assert.isFinite(NaN) // fails

Name	Type
`value`	`any`
`message?`	`string`

isFunction

Assert the value is a function.

assert.isFunction(function foo () {}) // passes
assert.isFunction(() => {}) // passes
assert.isFunction(class Foo {}) // passes

Name	Type
`value`	`any`
`message?`	`string`

isNotFunction

Assert the value is not a function

assert.isNotFunction({}) // passes
assert.isNotFunction(null) // passes
assert.isNotFunction(() => {}) // fails

Name	Type
`value`	`any`
`message?`	`string`

isNaN

Assert the value is NaN

assert.isNaN(NaN) // passes
assert.isNaN(Number('hello')) // passes
assert.isNaN(true) // fails
assert.isNaN(false) // fails
assert.isNaN(null) // fails

Name	Type
`value`	`any`
`message?`	`string`

isNotNaN

Assert the value is anything, but not NaN.

assert.isNotNaN(NaN) // fails
assert.isNotNaN(Number('hello')) // fails
assert.isNotNaN(true) // passes
assert.isNotNaN(false) // passes
assert.isNotNaN(null) // passes

Name	Type
`value`	`any`
`message?`	`string`

isNull

Assert the value is null

assert.isNull(null) // passes
assert.isNull(true) // fails
assert.isNull(false) // fails
assert.isNull('foo') // fails

Name	Type
`value`	`any`
`message?`	`string`

isNotNull

Assert the value is anything but not null

assert.isNotNull(null) // fails
assert.isNotNull(true) // passes
assert.isNotNull(false) // passes
assert.isNotNull('foo') // passes

Name	Type
`value`	`any`
`message?`	`string`

isNumber

Assert the value to be a valid number.

assert.isNumber(1) // passes
assert.isNumber(new Number('1')) // passes
assert.isNumber('1') // fails

Name	Type
`value`	`any`
`message?`	`string`

isNotNumber

Assert the value not to be a valid number.

assert.isNotNumber('1') // passes
assert.isNotNumber(1) // fails

Name	Type
`value`	`any`
`message?`	`string`

isObject

Assert the value to a valid object literal.

assert.isObject({}) // passes
assert.isObject(new SomeClass()) // passes
assert.isObject(null) // fails
assert.isObject([]) // fails

Name	Type
`object`	`any`
`message?`	`string`

isNotObject

Assert the value not to be an object literal.

assert.isNotObject(null) // passes
assert.isNotObject([]) // passes
assert.isNotObject({}) // fails
assert.isNotObject(new SomeClass()) // fails

Name	Type
`value`	`any`
`message?`	`string`

isString

Assert the value to be a literal string.

assert.isString('') // passes
assert.isString(new String(true)) // passes
assert.isString(1) // fails

Name	Type
`value`	`any`
`message?`	`string`

isNotString

Assert the value not to be a string literal.

assert.isNotString(1) // passes
assert.isNotString('') // fails
assert.isNotString(new String(true)) // fails

Name	Type
`value`	`any`
`message?`	`string`

isTrue

Assert the value is a boolean (true).

assert.isTrue(true) // passes
assert.isTrue(false) // fails
assert.isTrue(1) // fails
assert.isTrue('foo') // fails

Name	Type
`value`	`any`
`message?`	`string`

isNotTrue

Assert the value is anything, but not true.

assert.isNotTrue(true) // fails
assert.isNotTrue(false) // passes
assert.isNotTrue(1) // passes
assert.isNotTrue('foo') // passes

Name	Type
`value`	`any`
`message?`	`string`

closeTo

Assert the value is closer to the expected value + delta.

assert.closeTo(10, 6, 8) // passes
assert.closeTo(10, 6, 4) // passes
assert.closeTo(10, 20, 10) // passes

fail

Throw an error. Optionally accepts actual and expected values for the default error message.

The actual and expected values are not compared. However, they are available as properties on the AssertionError.

assert.fail() // fail
assert.fail('Error message for the failure')
assert.fail(1, 2, 'expected 1 to equal 2')
assert.fail(1, 2, 'expected 1 to be greater than 2', '>')

Name	Type
`message?`	`string`

Name	Type
`actual`	`any`
`expected`	`any`
`message?`	`string`
`operator?`	`string`

plan

Plan assertions for the test. The test will be marked as failed when the actual assertions count does not match the planned assertions count.

assert.plan(2)

Name	Type
`assertionsToExpect`	`number`

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