JavaScript Unit Testing Examples

Example project to allow me to show how best to unit test a JavaScript Express application.

Install

Clone this repository and install the dependencies as follows:

git clone [email protected]:MarcL/js-unit-testing-framework.git
npm install

Running the tests

The code sets up a basic Express server with a few routes and some tests which cover testing the server setup. Run the test suite using npm:

npm test

JavaScript Tests

Take a look in the test directory to see all of the test code. There are lots of examples of different types of tests and how to create them.

Asynchronous functions and promises

Some examples of how to test asynchronous functions and promises, including some tips and tricks and gotchas.

Asynchronous function

• Timeout because done callback isn't called when function succeeds
• Passing test but slow because timer isn't stubbed
• Passing test and fast because timer is stubbed
• Timeout because done callback isn't called when function throws an error
• Passing test to call done callback when function throws an error

Promise : resolving

• Test passes incorrectly because Promise isn't returned
• Passing test because promise is returned
• Passing test because done callback is called after resolution
• Passing test because done callback is called after resolution using chai-as-promised syntax

Promise : rejecting

• Test passes incorrectly because Promise isn't returned
• Failing test because rejected Promise error isn't caught
• Passing test because Promise is returned and rejection is caught
• Passing test because Promise rejection is caught and done callback is called
• Passing test because Promise rejection is caught and done callback is called using chai-as-promised syntax

Slow tests

• Passing test but is slow due to Promise function in chain taking a long time
• Passing test and much faster as longer function is now stubbed to execute immediately

License

See LICENSE