Test implementation guidelines for Ignite UI for Angular

Revision History

Version	User	Date	Notes
0.1	Zdravko Kolev	June 10, 2019	Initial version
0.2	Nikolay Alipiev	January 17, 2020	Angular component unit testing
0.3	Nikolay Alipiev / Plamena Miteva	March 30, 2020	Define new Guidelines

• Radoslav Karaivanov | Date:
• Konstantin Dinev | Date:

Prerequisites

• Angular Testing Guide
• Jasmine
• Run tests locally with ng test igniteui-angular

Examples

Here are some good examples of how to write new tests and how some of the old ones are refactored using the guide below.

New tests

Refactored tests

• igx-combo

Test implementation guidelines

Note: those guidelines should be applied only if reasonable

Globals

1. Define constants, when using a class name as a selector, at the top of the tests:

const CSS_CLASS_DRAG_ROW = 'igx-grid__tr--drag';

2. Define types for all variables and parameters:

let grid: IgxGridComponent;

3. The helper functions for the tests are in HelperUtils. Review and reuse them in tests instead of rewriting them.

4. For better performance, use NoopAnimationsModule to disable animatoions in tests if they are not the subject of testing:

import { NoopAnimationsModule } from '@angular/platform-browser/animations';

5. Implement different tests for each scenario, based on the Test plan.

Describes & TestBeds

1. Describes should be organized according to features/functionalities
2. Create one TestBed for each describe using beforeAll
3. In the TestBed declarations put only components which are used in the tests bellow and import necessary dependencies

describe('Initialization and rendering tests: ', () => {
    configureTestSuite();
    beforeAll(async(() => {
        TestBed.configureTestingModule({
            declarations: [
                IgxComboSampleComponent
            ],
            imports: [
                IgxComboModule,
                NoopAnimationsModule,
                IgxToggleModule
            ]
        }).compileComponents();
    }));
    ...

4. Call the configureTestSuite() method before the TestBed setup.

describe('Initialization and rendering tests: ', () => {
    configureTestSuite();

5. Use beforeEach in cases when all the tests use only one TestBed component rather than duplicate the TestBed initialization Example:

describe('IgxGrid - Multi Cell selection', () => {
    configureTestSuite();
    beforeEach(async(() => {
        TestBed.configureTestingModule({
            declarations: [
                SelectionWithScrollsComponent,
                SelectionWithTransactionsComponent
            ],
            imports: [NoopAnimationsModule, IgxGridModule]
        }).compileComponents();
    }));
    describe('Base', () => {
        ...
        beforeEach(fakeAsync(/** height/width setter rAF */() => {
           fixture = TestBed.createComponent(TestComponentX);
           ...
        }));

        it('Should be able to select a range with mouse dragging', () => {
...

6. When creating tests for the grids (igxGrid, igxTreeGrid, igxHieraticalGrid) try to use or extend one of the TestBeds from the files grid-base-components.spec, grid-samples.spec and tree-grid-components.spec.ts. If none of them is suitable for your scenario add the new TestBed to one of these files so it can be easily reused later.

7. Variables used in all/many tests is better to be defined in the scope of the describe and then reassigned when needed rather than repeat their declaration in each test:

describe('Custom ghost template tests', () => {
     let grid: IgxGridComponent;
     let rows: IgxGridRowComponent[];
     let dragRows: DebugElement[];
     configureTestSuite();
     beforeAll(async(() => {
     ...

Unit testing

One of the techniques for unit testing is to create a component/service/directive and inject its dependencies by hand while calling its constructor as described in Angular tutorials. Here is an example of such an approach:

select = new IgxSelectComponent(null, mockCdr, mockSelection, null, mockInjector);

There are several approaches to create a dependency:

• calling its constructor

const selectionService = new IgxSelectionAPIService();
combo = new IgxComboComponent({ nativeElement: null }, mockCdr, selectionService, mockComboService, null, mockInjector);

However, creating the real component or service might be a rather difficult task sometimes as it may rely on several other dependencies which also have to be created and injected.

• mock the dependency with fake class
• use a dummy value

elementRef = { nativeElement: { value: '20/02/2019 23:15:12' } };
dateTimeEditor = new IgxDateTimeEditorDirective(elementRef, maskParsingService, renderer2, DOCUMENT);

• create a spy

const mockSelection: {
            [key: string]: jasmine.Spy
        } = jasmine.createSpyObj('IgxSelectionAPIService', ['get', 'set', 'add_items', 'select_items']);
 combo = new IgxComboComponent({ nativeElement: null }, mockCdr, mockSelection as any, mockComboService, null, mockInjector);

Testing Asynchronous Code

When testing asynchronous code avoid using whenStable, done and setTimeout functions. Try to use fakeAsync and tick instead. The tick() function blocks execution and simulates the passage of time until all pending asynchronous activities complete.

it('should toggle drop down on open/close methods call', fakeAsync(() => {
                ...
                dropdown.open();
                tick();
                fixture.detectChanges();
                ...
));

If the above approach is not possible use async and await wait

 it('should properly call dropdown navigateNext with virtual items', (async () => {
                ...
                combo.toggle();
                await wait(30);
                fixture.detectChanges(); 
                ...
});

When testing virtualization you will need to use async since the code runs out of the Angular zone. It is also recommended to use the igxFor scroll methods like scrollTo instead of key interactions

 it('should preserve selection on scrolling', (async () => {
                ...
                combo.virtualScrollContainer.scrollTo(16);
                await wait(30);
                fixture.detectChanges();
                ...
});

UI Interactions & Events

To simulate an event in a test use the Angular DebugElement instance method triggerEventHandler(), instead of dispatchEvent().

selectedItem.triggerEventHandler('click', UIInteractions.clickEvent);
fixture.detectChanges();

The UIInteractions file (ui-interactions.spec) already has lots of functions covering keyboard and mouse events that can be used

`UIInteractions.triggerKeyDownEvtUponElem('tab', cell.nativeElement, true)`, 

Another option is to directly call the API methods:

rowDragDirective = dragRows[1].injector.get(IgxRowDragDirective);
rowDragDirective.onPointerDown(UIInteractions.createPointerEvent('pointerdown', startPoint));

Spies

Use Jasmine spies to stub any function and track calls to it and all arguments

    it('should not trigger onRemove event when ..', () => {
        ...
        const firstChipComp = fix.componentInstance.chips.toArray()[0];
        spyOn(firstChipComp.onRemove, 'emit');

This is especially useful in cases when we do not want the actual method to be called. The spy will replace the method with a stub that tracks if the method got called

    // Spy the saveBlobToFile method so the files are not really created
    spyOn(ExportUtilities as any, 'saveBlobToFile');

Pending Specs

Call the pending function in the spec's body to mark a test as pending instead of declaring it with xit.

it('should correctly handle ngControl validity', () => {
            pending('Convert existing form test here');
        });

9. Create helper functions - remove duplication and eventually move it to util.js (or use logic from there, especially keyboard triggers). There is already a lot of code in util.

Refactor

In the end always do a self-review, to fix unclear test names, syntax errors, etc.

Future improvements

• Move e2e test outside unit test.
• Avoid defining test components in the test files. Define them in a separate file instead (for example, grid-samples.spec.ts) so they can be easily reused in other test files.