Unit tests are fast, lightweight, and designed to validate algorithmic complexity in isolation. We’ll learn how to write our code in such a way that the trickiest parts are easily unit testable without having to build large numbers of “stubs”.

Build a handlebars helper function that formats a number nicely for analytics dashboards. You must write your unit tests to fulfill these requirements:

• 23004 should be represented as 23.0K
• -914 should be represented as -914
• 1060241 should be represented as 1.1M

Integration tests are designed to ensure interfaces or connections between components of your application work properly. We’ll learn how to write tests for two important “interfaces” to any Express app:

• Ensuring that URLs are handled by the appropriate route,
• Ensuring that routes pass the expected data to views.

Write an integration tests suite to ensure that the GET /course view is passed the correct data to render its template.

Acceptance tests, sometimes called functional tests, are designed to ensure that critical user workflows work correctly and protect them from regression. Acceptance tests are the closest thing we have to simulating user behavior. They should be designed in such a way that they mimic what users may do. Acceptance tests usually involve starting up the entire app and are considerably slower than unit or acceptance tests. You should have a few of these, but the more you have, the slower your test suite will be.

Build acceptance tests for the /api/course JSON Create, Read, Update and Destroy endpoints.

Build acceptance tests for the /course HTML Create, Read, Update and Destroy endpoints.

We'll recap everything we have learned throughout the course, and discuss resources for future learning.