Assertions

Sinon.JS ships with a set of assertions that mirror most behavior verification methods and properties on spies and stubs. The advantage of using the assertions is that failed expectations on stubs and spies can be expressed directly as assertion failures with detailed and helpful error messages.

To make sure assertions integrate nicely with your test framework, you should customize either sinon.assert.fail or sinon.assert.failException and look into sinon.assert.expose and sinon.assert.pass.

The assertions can be used with either spies or stubs.

"test should call subscribers with message as first argument" : function () {
    var message = "an example message";
    var spy = sinon.spy();

    PubSub.subscribe(message, spy);
    PubSub.publishSync(message, "some payload");

    sinon.assert.calledOnce(spy);
    sinon.assert.calledWith(spy, message);
}

Assertions API

sinon.assert.fail(message)

Every assertion fails by calling this method.

By default it throws an error of type sinon.assert.failException.

If the test framework looks for assertion errors by checking for a specific exception, you can simply override the kind of exception thrown. If that does not fit with your testing framework of choice, override the fail method to do the right thing.

sinon.assert.failException;

Defaults to AssertError.

sinon.assert.pass(assertion);

Called every time assertion passes.

Default implementation does nothing.

sinon.assert.notCalled(spy);

Passes if spy was never called

sinon.assert.called(spy);

Passes if spy was called at least once.

sinon.assert.calledOnce(spy);

Passes if spy was called once and only once.

sinon.assert.calledTwice(spy);

Passes if spy was called exactly twice.

sinon.assert.calledThrice(spy)

Passes if spy was called exactly three times.

sinon.assert.callCount(spy, num)

Passes if spy was called exactly num times.

sinon.assert.callOrder(spy1, spy2, ...)

Passes if provided spies were called in the specified order.

sinon.assert.calledOn(spy, obj)

Passes if spy was ever called with obj as its this value.

sinon.assert.alwaysCalledOn(spy, obj)

Passes if spy was always called with obj as its this value.

sinon.assert.calledWith(spy, arg1, arg2, ...);

Passes if spy was called with the provided arguments.

sinon.assert.alwaysCalledWith(spy, arg1, arg2, ...);

Passes if spy was always called with the provided arguments.

sinon.assert.neverCalledWith(spy, arg1, arg2, ...);

Passes if spy was never called with the provided arguments.

sinon.assert.calledWithExactly(spy, arg1, arg2, ...);

Passes if spy was called with the provided arguments and no others.

sinon.assert.alwaysCalledWithExactly(spy, arg1, arg2, ...);

Passes if spy was always called with the provided arguments and no others.

sinon.assert.calledWithMatch(spy, arg1, arg2, ...)

Passes if spy was called with matching arguments.

This behaves the same way as sinon.assert.calledWith(spy, sinon.match(arg1), sinon.match(arg2), ...).

sinon.assert.alwaysCalledWithMatch(spy, arg1, arg2, ...)

Passes if spy was always called with matching arguments.

This behaves the same way as sinon.assert.alwaysCalledWith(spy, sinon.match(arg1), sinon.match(arg2), ...).

sinon.assert.neverCalledWithMatch(spy, arg1, arg2, ...)

Passes if spy was never called with matching arguments.

This behaves the same way as sinon.assert.neverCalledWith(spy, sinon.match(arg1), sinon.match(arg2), ...).

sinon.assert.threw(spy, exception);

Passes if spy threw the given exception.

The exception can be a String denoting its type, or an actual object.

If only one argument is provided, the assertion passes if spy ever threw any exception.

sinon.assert.alwaysThrew(spy, exception);

Like above, only required for all calls to the spy.

sinon.assert.match(actual, expectation);

Uses sinon.match to test if the arguments can be considered a match.

var sinon = require('sinon');

describe('example', function(){
    it('should match on `x` property, and ignore `y` property', function() {
        var expected = {x: 1},
            actual = {x: 1, y: 2};

        sinon.assert.match(actual, expected);
    });
});

sinon.assert.expose(object, options);

Exposes assertions into another object, to better integrate with the test framework. For instance, JsTestDriver uses global assertions, and to make Sinon.JS assertions appear alongside them, you can do.

sinon.assert.expose(this);

This will give you assertCalled(spy),assertCallOrder(spy1, spy2, ...) and so on.

The method accepts an optional options object with two options.

prefix

is a prefix to give assertions. By default it is "assert", so sinon.assert.called becomes target.assertCalled. By passing a blank string, the exposed method will be target.called.

includeFail

true by default, copies over the fail and failException properties