angular4-testing/project-manager/src/app/blog/blog.component.spec.ts

import {BlogComponent} from './blog.component'

describe('Blog Component Isolated Test', () => {

  let blogComponent: BlogComponent;

  beforeEach(() => {
     blogComponent = new BlogComponent(null, null, null);
  });

  it('should have initial entries', () => {
    expect(blogComponent.entries.length).toBe(2);
    blogComponent.entries.forEach((entry) => {
      expect(entry.id).toBeLessThanOrEqual(blogComponent.id);
      expect(entry.createdAt.getDate()).toBe(new Date().getDate());
    })
  });

  it('should create new list entry and increment id', () => {
    let preCreationId = blogComponent.id;
    let entryTitle = "some fancy title";
    let entryImage = "https://avatars1.githubusercontent.com/u/3284117";
    let entryText = "some important text";
    blogComponent.createBlogEntry(entryTitle, entryImage, entryText);

    let newEntry = blogComponent.entries[blogComponent.entries.length - 1];
    expect(newEntry.id - 1).toBe(preCreationId);
    expect(newEntry.image).toBe(entryImage);
    expect(newEntry.text).toBe(entryText);
    expect(newEntry.createdAt.getDate()).toBe(new Date().getDate());
  });

  it('should delete entry by given id - and not change global max-id', () => {
    let preDeletionId = blogComponent.id;
    let latestId = blogComponent.entries[blogComponent.entries.length - 1].id;
    blogComponent.deleteBlogEntry(latestId);

    expect(blogComponent.id).toBe(preDeletionId);
    expect(() => {
      if (blogComponent.entries.length > 0) {
        return blogComponent.entries[blogComponent.entries.length - 1];
      } else {
        return 0;
      }
    }).not.toBe(latestId);
  });
});