Angular5+ test mock

mock.ts

import {Pipe, PipeTransform, Type, Component, Directive, EventEmitter } from '@angular/core';

/**
 * Examples:
 * MockPipe('some-pipe');
 * MockPipe('some-pipe', () => 'foo');
 */
export function MockPipe(name: string, transform?: any): Pipe {
  
  class Mock implements PipeTransform {
    transform = transform || () => undefined;
  }

  return Pipe({name:name})(Mock as any);
}

/**
 * Examples:
 * MockComponent({selector: 'some-component'});
 * MockComponent({selector: 'some-component', inputs: ['some-input', 'some-other-input']});
 */
export function MockComponent(options: Component): Component {

  const metadata: Component = {
    selector: options.selector,
    template: options.template || '',
    inputs: options.inputs,
    outputs: options.outputs || [],
    exportAs: options.exportAs || ''
  };

  class Mock {
    constructor() {
      metadata.outputs.forEach(method => {
        this[method] = new EventEmitter<any>();
      });
    }
  }

  return Component(metadata)(Mock as any);
}

/**
 * Examples:
 * MockDirective({selector: '[some-directive]'});
 * MockDirective({selector: '[some-directive]', inputs: ['some-input', 'some-other-input']});
 */
export function MockDirective(options: Directive): Directive {

  const metadata: Directive = {
    selector: options.selector,
    inputs: options.inputs,
    outputs: options.outputs || [],
    providers: options.providers || [],
    exportAs: options.exportAs || ''
  };

  class Mock {
    constructor() {
      metadata.outputs.forEach(method => {
        this[method] = new EventEmitter<any>();
      });
    }
  }

  return Directive(metadata)(Mock as any);
}