Our testing toolchain will consist of the following tools:
Jasmine is the most popular testing framework in the Angular community. This is the core framework that we will write our unit tests with.
Karma is a test automation tool for controlling the execution of our tests and what browser to perform them under. It also allows us to generate various reports on the results. For one or two tests this may seem like overkill, but as an application grows larger and the number of units to test grows, it is important to organize, execute and report on tests in an efficient manner. Karma is library agnostic so we could use other testing frameworks in combination with other tools (like code coverage reports, spy testing, e2e, etc.).
Istanbul is used by Karma to generate code coverage reports, which tells us the overall percentage of our application being tested. This is a great way to track which components/services/pipes/etc. have tests written and which don't. We can get some useful insight into how much of the application is being tested and where.
For some extra testing functionality we can use the Sinon library for things like test spys, test subs and mock XHR requests. This is not necessarily required as Jasmine comes with the spyOn function for incorporating spy tests.
Chai is an assertion library that can be paired with any other testing framework. It offers some syntactic sugar that lets us write our unit tests with different verbiage - we can use a should, expect or assert interface. Chai also takes advantage of "function chaining" to form English-like sentences used to describe tests in a more user friendly way. Chai isn't a required library for testing and we won't explore it much more in this handout, but it is a useful tool for creating cleaner, more well-written tests.