Angular 2 Testing a pipe


Example

Given a pipe that reverse a string

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({ name: 'reverse' })
export class ReversePipe implements PipeTransform {
  transform(value: string): string {
    return value.split('').reverse().join('');
  }
}

It can be tested configuring the spec file like this

import { TestBed, inject } from '@angular/core/testing';

import { ReversePipe } from './reverse.pipe';

describe('ReversePipe', () => {
  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [ReversePipe],
    });
  });

  it('should be created', inject([ReversePipe], (reversePipe: ReversePipe) => {
    expect(reversePipe).toBeTruthy();
  }));

  it('should reverse a string', inject([ReversePipe], (reversePipe: ReversePipe) => {
    expect(reversePipe.transform('abc')).toEqual('cba');
  }));
});