angular-docs-cn/packages/common/test/directives/ng_style_spec.ts

/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {CommonModule} from '@angular/common';
import {Component} from '@angular/core';
import {async, ComponentFixture, TestBed} from '@angular/core/testing';

{
  describe('NgStyle', () => {
    let fixture: ComponentFixture<TestComponent>;

    function getComponent(): TestComponent {
      return fixture.componentInstance;
    }

    function expectNativeEl(fixture: ComponentFixture<any>): any {
      return expect(fixture.debugElement.children[0].nativeElement);
    }

    afterEach(() => {
      fixture = null!;
    });

    beforeEach(() => {
      TestBed.configureTestingModule({declarations: [TestComponent], imports: [CommonModule]});
    });

    it('should add styles specified in an object literal', async(() => {
         const template = `<div [ngStyle]="{'max-width': '40px'}"></div>`;
         fixture = createTestComponent(template);
         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'max-width': '40px'});
       }));

    it('should add and change styles specified in an object expression', async(() => {
         const template = `<div [ngStyle]="expr"></div>`;
         fixture = createTestComponent(template);

         getComponent().expr = {'max-width': '40px'};
         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'max-width': '40px'});

         let expr = getComponent().expr;
         expr['max-width'] = '30%';
         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'max-width': '30%'});
       }));

    it('should add and remove styles specified using style.unit notation', async(() => {
         const template = `<div [ngStyle]="{'max-width.px': expr}"></div>`;

         fixture = createTestComponent(template);

         getComponent().expr = '40';
         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'max-width': '40px'});

         getComponent().expr = null;
         fixture.detectChanges();
         expectNativeEl(fixture).not.toHaveCssStyle('max-width');
       }));

    // https://github.com/angular/angular/issues/21064
    it('should add and remove styles which names are not dash-cased', async(() => {
         fixture = createTestComponent(`<div [ngStyle]="{'color': expr}"></div>`);

         getComponent().expr = 'green';
         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'color': 'green'});

         getComponent().expr = null;
         fixture.detectChanges();
         expectNativeEl(fixture).not.toHaveCssStyle('color');
       }));

    it('should update styles using style.unit notation when unit changes', async(() => {
         const template = `<div [ngStyle]="expr"></div>`;

         fixture = createTestComponent(template);

         getComponent().expr = {'max-width.px': '40'};
         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'max-width': '40px'});

         getComponent().expr = {'max-width.em': '40'};
         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'max-width': '40em'});
       }));

    // keyValueDiffer is sensitive to key order #9115
    it('should change styles specified in an object expression', async(() => {
         const template = `<div [ngStyle]="expr"></div>`;

         fixture = createTestComponent(template);

         getComponent().expr = {
           // height, width order is important here
           height: '10px',
           width: '10px'
         };

         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'height': '10px', 'width': '10px'});

         getComponent().expr = {
           // width, height order is important here
           width: '5px',
           height: '5px',
         };

         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'height': '5px', 'width': '5px'});
       }));

    it('should remove styles when deleting a key in an object expression', async(() => {
         const template = `<div [ngStyle]="expr"></div>`;

         fixture = createTestComponent(template);

         getComponent().expr = {'max-width': '40px'};
         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'max-width': '40px'});

         delete getComponent().expr['max-width'];
         fixture.detectChanges();
         expectNativeEl(fixture).not.toHaveCssStyle('max-width');
       }));

    it('should co-operate with the style attribute', async(() => {
         const template = `<div style="font-size: 12px" [ngStyle]="expr"></div>`;

         fixture = createTestComponent(template);

         getComponent().expr = {'max-width': '40px'};
         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'max-width': '40px', 'font-size': '12px'});

         delete getComponent().expr['max-width'];
         fixture.detectChanges();
         expectNativeEl(fixture).not.toHaveCssStyle('max-width');
         expectNativeEl(fixture).toHaveCssStyle({'font-size': '12px'});
       }));

    it('should co-operate with the style.[styleName]="expr" special-case in the compiler',
       async(() => {
         const template = `<div [style.font-size.px]="12" [ngStyle]="expr"></div>`;

         fixture = createTestComponent(template);

         getComponent().expr = {'max-width': '40px'};
         fixture.detectChanges();
         expectNativeEl(fixture).toHaveCssStyle({'max-width': '40px', 'font-size': '12px'});

         delete getComponent().expr['max-width'];
         fixture.detectChanges();
         expectNativeEl(fixture).not.toHaveCssStyle('max-width');
         expectNativeEl(fixture).toHaveCssStyle({'font-size': '12px'});
       }));

    it('should not write to the native node unless the bound expression has changed', () => {
      const template = `<div [ngStyle]="{'color': expr}"></div>`;

      fixture = createTestComponent(template);
      fixture.componentInstance.expr = 'red';

      fixture.detectChanges();
      expectNativeEl(fixture).toHaveCssStyle({'color': 'red'});

      // Overwrite native styles so that we can check if ngStyle has performed DOM manupulation to
      // update it.
      fixture.debugElement.children[0].nativeElement.style.color = 'blue';
      fixture.detectChanges();
      // Assert that the style hasn't been updated
      expectNativeEl(fixture).toHaveCssStyle({'color': 'blue'});

      fixture.componentInstance.expr = 'yellow';
      fixture.detectChanges();
      // Assert that the style has changed now that the model has changed
      expectNativeEl(fixture).toHaveCssStyle({'color': 'yellow'});
    });

    it('should correctly update style with units (.px) when the model is set to number', () => {
      const template = `<div [ngStyle]="{'width.px': expr}"></div>`;
      fixture = createTestComponent(template);
      fixture.componentInstance.expr = 400;

      fixture.detectChanges();
      expectNativeEl(fixture).toHaveCssStyle({'width': '400px'});
    });
  });
}

@Component({selector: 'test-cmp', template: ''})
class TestComponent {
  expr: any;
}

function createTestComponent(template: string): ComponentFixture<TestComponent> {
  return TestBed.overrideComponent(TestComponent, {set: {template: template}})
      .createComponent(TestComponent);
}