hamjest/test/node/matchers/IsInstanceOfSpec.js

A library of composable matchers for defining meaningful and readable assertions in JavaScript.

'use strict';

const assert = require('assert');
const AssertionError = require('assertion-error');

const __ = require('../../..');
const zoo = require('../zoo');

const Animal = zoo.Animal;
const Rodent = zoo.Rodent;
const Squirrel = zoo.Squirrel;

describe('IsInstanceOf', () => {

	describe('instanceOf', () => {
		let sut;
		beforeEach(() => {
			sut = __.instanceOf(Rodent);
		});

		it('should throw for non-function arguments', () => {
			__.assertThat(() => {
				__.instanceOf('a value');
			}, __.throws(__.instanceOf(AssertionError)));
		});

		it('should match instances and subinstances', () => {
			assert.equal(sut.matches(new Animal()), false);
			assert.ok(sut.matches(new Rodent()));
			assert.ok(sut.matches(new Squirrel()));
		});

		it('should not match undefined', () => {

			assert.equal(sut.matches(undefined), false);
		});

		describe('description', () => {
			let description;

			beforeEach(() => {
				description = new __.Description();
			});

			it('should contain instance name', () => {

				sut.describeTo(description);

				__.assertThat(description.get(), __.equalTo('an instance of Rodent'));
			});

			it('should insert placeholder for anonymous functions', () => {
				sut = __.instanceOf(() => {});

				sut.describeTo(description);

				__.assertThat(description.get(), __.equalTo('an instance of ANONYMOUS FUNCTION'));
			});

			it('should contain mismatched type', () => {

				sut.describeMismatch('another value', description);

				__.assertThat(description.get(), __.equalTo('"another value" is a String'));
			});

			it('should handle undefined value', () => {

				sut.describeMismatch(undefined, description);

				__.assertThat(description.get(), __.equalTo('was undefined'));
			});

			it('should contain mismatched type for custom types', () => {

				sut.describeMismatch(new Animal(), description);

				__.assertThat(description.get(), __.equalTo('{} is a Animal'));
			});
		});
	});
});