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@typed/assertions

Get It

npm install --save-dev @typed/assertions
# or 
yarn add --dev @typed/assertions

Basic usage

import { equal, ok } from '@typed/assertions'
 
class Foo {
  constructor() {
    this.bar = 'bar'
  }
}
 
// with mocha
describe('Foo', () => {
  it(`does bar`, () => {
    const foo = new Foo()
 
    ok(foo instanceof Foo)
    equal('bar', foo.bar)
  })
})

API

createAssertionsEnvironment(): AssertionEnvironment

Creates an Assertions Environment where assertions can be counted

Example:

import { createAssertionsEnvironment } from '@typed/assertions'
 
const { stats, assertions } = createAssertionsEnvironment()
 
const { ok } = assertions
 
console.log(stats.count) // => 0
 
ok(true)
 
console.log(stats.count) // => 1

equal<A>(expected: A, actual: A): A

Checks if 2 values are equal in terms of value equality

Example:

import { equal } from '@typed/assertions'
 
equal({ a: 1 }, { a: 2 }) // throws AssertionError

notEqual<A>(expected: A, actual: A): A

Checks if two values are not equal in terms of value equality

Example:

import { notEqual } from '@typed/assertions'
 
notEqual({ a: 1 }, { a: 2 }) // => { a: 2 }
 
notEqual({ a: 1 }, { a: 1 }) // throws AssertionError

notOk(actual: boolean): boolean

Checks if a value is false

Example:

import { notOk } from '@typed/assertions'
 
notOk(false) // => false
notOk(true) // throws AssertionError

ok(actual: boolean): boolean

Checks if a value is true

Example:

import { ok } from '@typed/assertions'
 
ok(false) // throws AssertionError
ok(true) // => true

rejects<Err extends Error>(promise: Promise<any>): Promise<Err>

Asserts that a Promise has rejected, returning a resolved Promise containing the error.
If the promise does not reject returns a rejected Promise.

Example:

import { rejects } from '@typed/assertions'
 
rejects(Promise.reject(new Error('foo))) // => resolved Promise containing Error('foo')
rejects(Promise.resolve()) // => rejected Promise

same<A>(expected: A, actual: A): A

Checks if 2 values are the same in terms of ===

Example:

import { same } from '@typed/assertions'
 
same({}, {}) // throws AssertionError
same(1, 1) // => 1

throws<Err extends Error>(fn: () => any): Err

Asserts that the given function throws

Example:

import { throws } from '@typed/assertions'
 
throws(() => { throw new Error('foo') }) // => Error('foo')
throws(() => {}) // throws Error