Testility

This package contains a few useful tools for writing unit tests in Typescript or JavaScript.

Random Data Generators

Whenever you need to generate a random number, string, boolean or object, use these classes to generate the data for you. Here's how:

import { RANDOM_NUMBER, RANDOM_STRING, RANDOM_BOOLEAN, RANDOM_OBJECT } from '../testility';

// All random data generators include getOne and getMany methods
// The latter allows you to specify the number of records (default 20)

// You can control the min/max value for random numbers
let randomNumber = RANDOM_NUMBER.getOne();
let randomNumbers = RANDOM_NUMBER.getMany();
let twentyRandomNumbers = RANDOM_NUMBER.getMany(20);
let randomNumberBetween50And100 = RANDOM_NUMBER.getOne(50, 100);
let twentyRandomNumbersBetween50And100 = RANDOM_NUMBER.getOne(20, 50, 100);

// You can control the length of random strings
let randomString = RANDOM_STRING.getOne();
let randomStringOfTenCharacters = RANDOM_STRING.getOne(10);
let threeRandomStrings = RANDOM_STRING.getMany(3);
let threeRandomCharacters = RANDOM_STRING.getMany(3, 1);

// You can control the false threshold for random booleans
let randomBoolean = RANDOM_BOOLEAN.getOne();
let randomBoolean90PercentFalse = RANDOM_BOOLEAN.getOne(0.9);
let randomBooleans = RANDOM_BOOLEAN.getMany();
let fourRandomBooleans = RANDOM_BOOLEAN.getMany(4);
let fiftyRandomBooleansEightPercentTrue = RANDOM_BOOLEAN.getMany(50, 0.2);

// You can control the number of properties on a random object
// Random objects include random properties and values, including array values
let randomObject = RANDOM_OBJECT.getOne();
let randomObjectWithTwoProperties = RANDOM_OBJECT.getOne(2);
let randomObjects = RANDOM_OBJECT.getMany();
let tenRandomObjects = RANDOM_OBJECT.getMany(10);
let tenRandomObjectsWithOnlyOneProperty = RANDOM_OBJECT.getMany(10, 1);

TestDataFactory

Based on a blog post I made called "Stop Filling Your Tests with Test Data", this super simple class gives you an easy way to create factories that generate test data for you. You provide a method to generate a single record, and you get back a Factory to generate as many records as you need. You can also override records in your test data in order to make your tests clearer. Here is an example:

import { TestDataFactory, RANDOM_NUMBER } from 'testility';
import { Customer } from './models';
import { CustomerDataService } from './customer.service';

export const CUSTOMER_FACTORY = new TestDataFactory(() => {
const id = RANDOM_NUMBER.getOne();
return {
id,
firstName: FIRSTNAME_${id},
lastName: LASTNAME_${id},
memberLevel: 1
};
});

describe('Customer Service', () => {
let unit: CustomerDataService;
let testData: any[];
beforeEach(() => {
testData = CUSTOMER_FACTORY.getMany(10, [
{ memberLevel: 3 },
{ memberLevel: 2 }
]);

unit = new CustomerDataService();
});

describe('when getPremiumMembers is called', () => {
let result: any[];
beforeEach(() => {
result = unit.getPremiumMembers(testData);
});

it('should return only the premium members', () => {
expect(result.length).toBe(1);
expect(result[0]).toBe(testData[0]);
});
});
});

MockPromise

This class provides an easy way to create a mock promise in your tests, which you can resolve at a time of your choosing. This allows you to make assertions before and after the promise resolves.

The wrapper contains a promise property, containing the actual promise, a result property for storing the return value (this isn't used internally but saves you having to create a separate variable for the return value and means you know where to find it), as well as two methods: resolve and reject, which allow you to resolve the promise or reject it at a time of your choosing. Here is an example:

import { MockPromiseWrapper } from 'testility';
import { PRODUCT_DATA_FACTORY } from './test-data';
import { ProductListComponent } from './product-component';

describe('Product List Component', () => {
let unit: ProductListComponent;
let mockService: any;
let mockPromiseWrapper: MockPromiseWrapper;

beforeEach(() => {
mockPromiseWrapper = new MockPromiseWrapper();
mockPromiseWrapper.result = PRODUCT_DATA_FACTORY.getMany(); // you don't have to use this, but it provides a convenient place to store your result - store on a separate variable if you prefer
mockService = {
getProducts: jasmine.createSpy().and.returnValue(mockPromiseWrapper.promise)
};
unit = new ProductListComponent(mockService);
});

it('should remove the loading message once products are loaded', (done) => {
expect(mockService.getProducts).toHaveBeenCalled();
expect(unit.element.textContent).toContain('Loading'); // This is the key part - if the promise resolved right away we can't reliably make this assertion

mockPromiseWrapper.resolve(mockPromiseWrapper.result).then((products) => {
expect(unit.element.textContent).not.toContain('Loading');
done();
});
});
});

Angular Template Test Component

I had a scenario where I was passing a template to a modal service, but wanted to test the contents of the template in the component where it is defined. It turns out that the best way to test this is to render the template and then make assertions on the content as you normally would. To make that easier, I created a wrapping component and a method to get you the ComponentFixture containing your rendered template:

import { TemplateTestComponent, renderTemplateRef } from '@maloric/testility/angular';

...

TestBed.configureTestingModule({
declarations: [
MyComponent, // My component under test
TemplateTestComponent
]
});
fixture = TestBed.createComponent(MyComponent);

...

it('should do something', () => {
// These two lines are just the way I was getting my templateRef
// Your exact way of getting to your templateRef may differ
let config = mockModal.show.calls.mostRecent().args[0];
let template = config.props.contentTemplate as TemplateRef;

// This is the important bit
let myModalContent = renderTemplateRef(template);

// And now I can look at the contents of my template as I would any other
let mySubComponent = myModalContent.debugElement.query(By.css('my-sub-component'));
expect(mySubComponent).toBeTruthy();
});