Awesome
Sinon.JS Assertions for Chai
Sinon–Chai provides a set of custom assertions for using the Sinon.JS spy, stub, and mocking framework with the Chai assertion library. You get all the benefits of Chai with all the powerful tools of Sinon.JS.
Instead of using Sinon.JS's assertions:
sinon.assert.calledWith(mySpy, "foo");
or awkwardly trying to use Chai's should
or expect
interfaces on spy properties:
mySpy.calledWith("foo").should.be.ok;
expect(mySpy.calledWith("foo")).to.be.ok;
you can say
mySpy.should.have.been.calledWith("foo");
expect(mySpy).to.have.been.calledWith("foo");
Assertions
All of your favorite Sinon.JS assertions made their way into Sinon–Chai. We show the should
syntax here; the expect
equivalent is also available.
Sinon.JS property/method | Sinon–Chai assertion |
---|---|
called | spy.should.have.been.called |
callCount | spy.should.have.callCount(n) |
calledOnce | spy.should.have.been.calledOnce |
calledTwice | spy.should.have.been.calledTwice |
calledThrice | spy.should.have.been.calledThrice |
calledBefore | spy1.should.have.been.calledBefore(spy2) |
calledAfter | spy1.should.have.been.calledAfter(spy2) |
calledImmediatelyBefore | spy.should.have.been.calledImmediatelyBefore(spy2) |
calledImmediatelyAfter | spy.should.have.been.calledImmediatelyAfter(spy2) |
calledWithNew | spy.should.have.been.calledWithNew |
alwaysCalledWithNew | spy.should.always.have.been.calledWithNew |
calledOn | spy.should.have.been.calledOn(context) |
alwaysCalledOn | spy.should.always.have.been.calledOn(context) |
calledWith | spy.should.have.been.calledWith(...args) |
alwaysCalledWith | spy.should.always.have.been.calledWith(...args) |
calledOnceWith | spy.should.always.have.been.calledOnceWith(...args) |
calledWithExactly | spy.should.have.been.calledWithExactly(...args) |
alwaysCalledWithExactly | spy.should.always.have.been.calledWithExactly(...args) |
calledOnceWithExactly | spy.should.always.have.been.calledOnceWithExactly(...args) |
calledWithMatch | spy.should.have.been.calledWithMatch(...args) |
alwaysCalledWithMatch | spy.should.always.have.been.calledWithMatch(...args) |
returned | spy.should.have.returned(returnVal) |
alwaysReturned | spy.should.have.always.returned(returnVal) |
threw | spy.should.have.thrown(errorObjOrErrorTypeStringOrNothing) |
alwaysThrew | spy.should.have.always.thrown(errorObjOrErrorTypeStringOrNothing) |
For more information on the behavior of each assertion, see the documentation for the corresponding spy methods. These of course work on not only spies, but individual spy calls, stubs, and mocks as well.
Note that you can negate any assertion with Chai's .not
. E. g. for notCalled
use spy.should.have.not.been.called
. Similarly, note that the always
methods are accessed with Chai's .always
prefix; should.have.been.alwaysCalledWith
will not work - instead, use should.always.have.been.calledWith
.
For simplicity, this library intentionally only implements Sinon's spy methods, and does not add an interface for Sinon.assert.match
. Sinon's matchers are implemented by the samsam
library, so if you want a should/expect interface to assert.match
you may be interested in chai-samsam, which adds a .deep.match
verb that will work with Sinon matchers.
For assert
interface there is no need for sinon-chai
or chai-samsam
. You can install Sinon.JS assertions right into Chai's assert
object with expose
:
import * as chai from "chai";
import sinon from "sinon";
sinon.assert.expose(chai.assert, { prefix: "" });
Examples
Using Chai's should
:
"use strict";
import * as chai from "chai";
import sinon from "sinon";
import sinonChai from "sinon-chai";
chai.should();
chai.use(sinonChai);
function hello(name, cb) {
cb("hello " + name);
}
describe("hello", function () {
it("should call callback with correct greeting", function () {
var cb = sinon.spy();
hello("foo", cb);
cb.should.have.been.calledWith("hello foo");
});
});
Using Chai's expect
:
"use strict";
import * as chai from "chai";
import sinon from "sinon";
import sinonChai from "sinon-chai";
const expect = chai.expect;
chai.use(sinonChai);
function hello(name, cb) {
cb("hello " + name);
}
describe("hello", function () {
it("should call callback with correct greeting", function () {
var cb = sinon.spy();
hello("foo", cb);
expect(cb).to.have.been.calledWith("hello foo");
});
});
Installation and Usage
Node
Do an npm install --save-dev sinon-chai
to get up and running. Then:
import * as chai from "chai";
import sinonChai from "sinon-chai";
chai.use(sinonChai);
You can of course put this code in a common test fixture file; for an example using Mocha, see the Sinon–Chai tests themselves.
Ruby on Rails
Thanks to Cymen Vig, there's now a Ruby gem of Sinon–Chai that integrates it with the Rails asset pipeline!