# Backend Testing
# Mocks
# Model
Create a src/models/__mocks__ directory and create a src/models/__mocks__/Blog.js file in your backend work space directory and the following mock code:
const Blog = require("../Blog");
// This is called by default in __mocks__
// jest.mock("../Blog");
const mockSave = jest.fn();
const mockPopulate = jest.fn();
Blog.mockImplementation(() => ({
save: mockSave,
}));
Blog.find.mockImplementation(() => ({
populate: () => ({
populate: mockPopulate,
}),
}));
Blog.findById.mockImplementation(() => ({
populate: () => ({
populate: mockPopulate,
}),
}));
const mockBlogPost = {
_id: "1",
title: "My First Blog Post - Jest Unit Test",
description:
"Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
categoryIds: [
{
id: "665945dbc2294698fe74d8d4",
title: "Frontend Development",
color: "#026AA2",
},
{
id: "665945ffc2294698fe74d8d9",
title: "Backend Development",
color: "#C11574",
},
],
authorId: "665e4736cdb3ef11df5134f3",
content: [
{
sectionHeader: "Introduction",
sectionText:
"I'm so excited to share my first blog post with the world. I've been working on this for a while and I'm happy to finally share it with you.\n\nLorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
},
{
sectionHeader: "Body",
sectionText:
"This is the body of my blog post. I hope you enjoy reading it as much as I enjoyed writing it.\n\nLorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
},
{
sectionHeader: "Conclusion",
sectionText:
"I hope you enjoyed reading my first blog post. I'm looking forward to sharing more with you in the future.\n\nLorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
},
],
image: "https://storage.googleapis.com/ix-blog-app/default.jpeg",
};
module.exports = Blog;
module.exports.__mocks__ = {
mockSave,
mockPopulate,
mockBlogPost,
};
# Services
Create a src/services/__mocks__ directory and create a src/models/__mocks__/google-cloud-storage.js file in your backend work space directory and the following mock code:
module.exports = {
uploadToFirebaseStorage: jest.fn(),
};
# Tests
# Controllers
Create a src/controllers/__tests__ directory and create a src/models/__tests__/blogController.js file in your backend work space directory and the following mock code:
// Import functions to test:
const { createBlogs, getBlogs } = require("../blogs");
// Import mocks:
jest.mock("../../models/Blog");
jest.mock("../../services/cloud-storage");
const Blog = require("../../models/Blog");
const cloudStorage = require("../../services/cloud-storage");
const { __mocks__ } = require("../../models/__mocks__/Blogs");
const mockReq = {
body: {
title: "My First Blog Post - Jest Unit Test",
description:
"Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
categories: JSON.stringify([
{
id: "665945dbc2294698fe74d8d4",
title: "Frontend Development",
color: "#026AA2",
},
{
id: "665945ffc2294698fe74d8d9",
title: "Backend Development",
color: "#C11574",
},
]),
authorId: "665e4736cdb3ef11df5134f3",
content: JSON.stringify([
{
sectionHeader: "Introduction",
sectionText:
"I'm so excited to share my first blog post with the world. I've been working on this for a while and I'm happy to finally share it with you.\n\nLorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
},
{
sectionHeader: "Body",
sectionText:
"This is the body of my blog post. I hope you enjoy reading it as much as I enjoyed writing it.\n\nLorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
},
{
sectionHeader: "Conclusion",
sectionText:
"I hope you enjoyed reading my first blog post. I'm looking forward to sharing more with you in the future.\n\nLorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
},
]),
},
file: {
path: "path/to/file",
},
};
// Tests:
describe("Blogs Controller: createBlogs", () => {
let req, res;
beforeEach(() => {
req = mockReq;
res = {
status: jest.fn(),
json: jest.fn(),
};
cloudStorage.uploadToFirebaseStorage.mockResolvedValue(
"https://storage.googleapis.com/ix-blog-app/default.jpeg"
);
Blog.mockClear();
__mocks__.mockSave.mockClear();
__mocks__.mockPopulate.mockClear();
});
test("Should create a blog and return the blog data", async () => {
__mocks__.mockSave.mockResolvedValue({ _id: "1" });
__mocks__.mockPopulate.mockResolvedValue(__mocks__.mockBlogPost);
await createBlogs(req, res);
expect(cloudStorage.uploadToFirebaseStorage).toHaveBeenCalledWith(
"path/to/file",
"path/to/file"
);
expect(Blog).toHaveBeenCalledWith({
title: req.body.title,
description: req.body.description,
image: "https://storage.googleapis.com/ix-blog-app/default.jpeg",
content: JSON.parse(req?.body?.content),
authorId: req.body.authorId,
categoryIds: ["665945dbc2294698fe74d8d4", "665945ffc2294698fe74d8d9"],
});
expect(__mocks__.mockSave).toHaveBeenCalled();
expect(__mocks__.mockPopulate).toHaveBeenCalled();
expect(Blog.findById).toHaveBeenCalledWith("1");
expect(res.status).toHaveBeenCalledWith(201);
expect(res.json).toHaveBeenCalledWith({
message: "Blog created!",
data: __mocks__.mockBlogPost,
});
});
test("should handle errors", async () => {
const error = new Error("Something went wrong");
__mocks__.mockSave.mockRejectedValue(error);
await createBlogs(req, res);
expect(res.status).toHaveBeenCalledWith(500);
expect(res.json).toHaveBeenCalledWith({ message: error.message, data: {} });
});
});
describe("Blogs Controller: getBlogs", () => {
beforeEach(() => {
req = {};
res = {
status: jest.fn(),
json: jest.fn(),
};
Blog.mockClear();
__mocks__.mockSave.mockClear();
__mocks__.mockPopulate.mockClear();
});
test("Should return all blogs data", async () => {
__mocks__.mockPopulate.mockResolvedValue([__mocks__.mockBlogPost]);
await getBlogs(req, res);
expect(res.status).toHaveBeenCalledWith(200);
expect(res.json).toHaveBeenCalledWith({
message: "Get all blogs!",
data: [__mocks__.mockBlogPost],
});
});
test("should handle get blogs errors", async () => {
const error = new Error("Something went wrong");
__mocks__.mockPopulate.mockRejectedValue(error);
await getBlogs(req, res);
expect(res.status).toHaveBeenCalledWith(500);
expect(res.json).toHaveBeenCalledWith({ message: error.message, data: {} });
});
});
# Coverage
← Jest Frontend Testing →