ndowkunda / loan-shield

A loan application validation app

LoanShield

LoanShield is a loan application validation app that provides protection and security for lenders. The app validates loan applications based on certain criteria and returns a response to the user indicating whether their loan application has been approved or declined.

Dependencies

LoanShield is built using the following dependencies:

• 🔗 Node.js - open-source, cross-platform, back-end JavaScript runtime environment
• 🔗 Express - Node.js web application framework.
• 🔗 Nodemon - A tool that automatically restarts the Node.js application when file changes in the directory are detected.
• 🔗 Pug - A high-performance template engine for Node.js, formerly known as Jade.
• 🔗 Jest - A JavaScript testing framework for Node.js, used for testing the application logic.
• 🔗 Supertest - A library used to test HTTP endpoints in Node.js, often used in combination with Jest.

Getting Started

🔗 view here

To start LoanShield locally:

1. Install Node.js on your machine if you haven't already done so.

2. Clone the repository to your local machine using the following command:

git clone https://github.com/your-username/LoanShield.git

3. Navigate to the project directory and install the necessary dependencies using the following command:

cd LoanShield
npm install

4. Start the app using the following command:

npm start

5. Navigate to https://localhost:3000 in your web browser to access the app.

Running Tests

To run the tests for the LoanShield app:

1. Ensure that the app is not currently running.

2. Run the tests using the following command:

npm test

This will run the tests using Jest and Supertest to make assertions on the router, controller, and validation logic.

Endpoints

The LoanShield app includes a POST /loan-applications endpoint that accepts customer data and returns a decision object indicating whether their loan application has been approved or declined. The response object will include a Decision property with the value of either "Approved" or "Rejected".

To use the POST /loan-applications endpoint, send a POST request to the following URL:

🔗 https://localhost:3000/loan-applications

The request body should include the following properties:

• dateOfBirth (string, required, format: YYYY-MM-DD): Customer's date of birth.
• annualIncome (string, required, format: number): Customer's annual income
• loanAmount (string, required), format: number) : Customer's requested loan amount
• residentialMonthlyExpenditure (string, required, format: number): Customer's stated monthly expenditure

Here's an example of a request body:

{
  "dateOfBirth": "1995-02-23",
  "annualIncome": "26000",
  "loanAmount": "5100",
  "residentialMonthlyExpenditure": "1000"
}

The response from the POST /loan-applications endpoint will be a decision object with the following properties:

Decision (string, required): Either "Approved" or "Rejected"

Here's an example of a response body:

{
  "Decision": "Approved"
}

Tests

Tests are organised with the domain separate from the app routes,controllers and services.

Here's a sample of the tests for the domain:

const { AnnualIncome } = require("../../src/Customer/Customer");

describe("Validate annual income", () => {
  it("should return true if amount is greater minimum annual income", () => {
    const annualIncome = new AnnualIncome(25000);
    const expectedResult = annualIncome.validate();
    expect(expectedResult).toBe(true);
  });
});

Here's a sample of the tests for the Services:

jest.mock(".../../../src/Customer/Age");
const {
  LoanValidationService,
} = require("../../src/Loan/services/Services");

describe("validate loan", () => {
  test("should throw error due to incorrect date of birth format", () => {
    const mockCustomerReq = {
      dateOfBirth: "20-02-2000",
      annualIncome: "50000",
      loanAmount: "20000",
      residentialMonthlyExpenditure: "900",
    };

    const mockAge = new Age(25);
    mockAge.errors = [];
    mockAge.validate = jest.fn((mockCustomerReq) => {
      throw new Error("Invalid date of birth");
    });

    const loanValidationService = new LoanValidationService([mockAge]);

    expect(() => loanValidationService.validate(mockCustomerReq)).toThrowError(
      "Loan application invalid"
    );
  });
})

Acknowledgements

This project was created and designed to give me hands-on experience with creating a RESTful API with SOLID principles in mind. Shout out to @NC-1234 providing me with this opportunity to practice and develop these skills:pray: