[Angular Unit Testing] Testing Pipe

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

@Pipe({

  name: 'filesize'

})

export class FileSizePipe implements PipeTransform {

  transform(size: number, extension: string = 'MB') {

    return (size / (1024 * 1024)).toFixed(2) + extension;

  }

}

import { FileSizePipe } from './file-size.pipe';

describe('FileSizePipe', () => {

  describe('Isolate FileSizePipe test', () => {

    const pipe = new FileSizePipe();

    it('should convert bytes to megabytes', () => {

      expect(pipe.transform(123456789)).toBe('117.74MB');

      expect(pipe.transform(987654321)).toBe('941.90MB');

    });

    it('should use the default extension when not supplied', () => {

      expect(pipe.transform(123456789)).toBe('117.74MB');

      expect(pipe.transform(987654321)).toBe('941.90MB');

    });

    it('should override the extension when supplied', () => {

      expect(pipe.transform(123456789, 'myExt')).toBe('117.74myExt');

      expect(pipe.transform(987654321, 'anotherExt')).toBe('941.90anotherExt');

    });

  });

});