Writing your first unit tests in an Angular project

Unit testing is a critical aspect of Angular development that ensures code quality, reliability, and maintainability. TDD is a software development approach that emphasizes writing tests before implementing the actual code. In this section, you’ll learn how to write your first unit tests in an Angular project while following the principles of TDD. By leveraging the Jasmine testing framework and Angular’s testing utilities, developers can create effective and robust unit tests that verify the correctness of their code.

We’ll be using the project we created in Chapter 1 to practice. Follow these steps to write your first unit test:

1. Create a new component called CalculatorComponent by running the following command:

   $ ng g m calculator --route calculator --module=app.module

   After creating the component with the preceding command line, a calculator.component.spec.ts file will be created in the src/ app/calculator...