CODEWITHSUNDEEP
javascriptresttestingsupertestnode-rest-client
Kesem David
Kesem David

Reputation: 2235

How to test a call to a REST service

I set up a server that provides several endpoints to clients, and I have a client that uses node-rest-client package to post data to the backend.

I would like to write some unit-testing for the client side, making sure the data is properly sent to the endpoint.

I've been thinking of setting a dummy server for the testing, but that doesn't feel right.

How can i acheive such tests?

Please let me know if there's any missing data.

Thanks in advance!

EDIT

I've been looking at supertest package, but it looks like this is used to test the REST API service itself and not to test the REST calls from the client

Upvotes: 2

Views: 2126

Answers (1)

tonicsoft
tonicsoft

Reputation: 1808

Setting up a dummmy server is a legitimate approach as part of your "Acceptance Testing" strategy. Unlike Unit Tests, Acceptance Tests test a single component (made up of many Units) in isolation, stubbing out any external factors like databases or back end HTTP services. Having a dummy server can be a good way to go if you want to test how your client side as a whole interacts with the back end HTTP service. Acceptance Tests are generally more wide reaching, fewer in number, and slower than Unit Tests. That's why it's OK to start a dummy HTTP server.

However, if you really want to Unit Test the individual javascript unit that makes calls to the server, then this can actually be a bit tricky. You don't want to start a real HTTP server in Unit Tests because it will make them slow and unable to run in parallel.

The best approach depends on the technology you are using. For example, AngularJS provides a way to Unit Test HTTP calls called $httpBackend. Essentially it is a dummy HTTP server, but it doesn't actually go over HTTP (all requests stay in memory). This is possible because the Angular Team view testability as a priority and designed it this way from the ground up.

I don't think the node-rest-client provides a similar sort of mock HTTP server so it may prove difficult to Unit Test your client. The best approach is probably to wrap all usages of the node-rest-client in a standalone javascript object which itself has no Unit Tests, but is easy to mock out in unit tests for other parts of your client side code. This un-unit tested object can then be tested against a dummy HTTP server as part of a separate test suite, or you could even rely on your Integration Tests to catch any problems with this part.

As always though, it is best to keep your reliance on Integration Tests (which connect to an actual instance of the back end) to a minimum as they are slow and unreliable. These tests should really only be for verifying top level details such as performance, connection details, configuration compatibility etc.

If you take the wrapping approach, it is important to have as little logic in the wrapper as possible, because it will not be Unit Tested!

Note that wrapping all HTTP calls in a javascript service object is probably good practice regardless of your testing strategy, as it will confine all usages of the node-rest-client to one place in your code.

Upvotes: 2

Related Questions