mock-server

A library allowing simple assertions about whether and how an HTTP endpoint was called.

When testing a service, you may want to make assertions about how external dependencies are called, or that your system behaves as you expect when an another system responds poorly.

For example, you may be testing an email confirmation flow, which makes HTTP requests to send emails to users. You'd like to call your API, and assert that it calls the external API. But you'd also like to see what happens when that external API:

• takes 5 minutes to respond?

• responds with a 500?

• fails, then succeeds?

etc.

Usage

deps.edn:

[net.clojars.jds02006/mock_server {:mvn/version "0.1.0-SNAPSHOT"}]

leiningen:

[net.clojars.jds02006/mock_server "0.1.0-SNAPSHOT"]

Usage is pretty simple. First require the namespace:

(require '[johnswanson.mock-server :as mock :refer [with-mock-server with-requests with-handler]])

You can use with-mock-server to launch the mock server. (You can also launch it manually with start-server!, in which case you'll need to manually shut it down with stop-server!.)

;; launch the mock HTTP server. By default, it just returns a 200 status and no body
(with-mock-server server
  (is (= 200 (:status (http/get (mock/url server))))))

If you want to inspect the requests your application has made to the server, you can use with-requests to collect requests into a vector:

(with-mock-server server
  (with-requests requests
    (http/get (mock/url server))
    (is (= :get (:request-method (first @requests))))))

Finally, if you want to change the behavior of the HTTP server (e.g. return 500 errors, or induce timeouts with a long sleep), you can do that as well! Just use with-handler:

(with-mock-server server
  (with-handler (fn [_req]
                  (Thread/sleep 10000)
                  {:status 404})
    ;; this will take 10 seconds!
    (is (= 404 (:status (http/get (mock/url server)))))))

You've probably figured it out by now, but mock/url is a function returning the URL for the mock server - probably something like "http://localhost:61022".

Building

Run the project's CI pipeline and build a JAR:

$ clojure -T:build ci

This will produce an updated pom.xml file with synchronized dependencies inside the META-INF directory inside target/classes and the JAR in target. You can update the version (and SCM tag) information in generated pom.xml by updating build.clj.

Install it locally (requires the ci task be run first):

$ clojure -T:build install

Deploy it to Clojars -- needs CLOJARS_USERNAME and CLOJARS_PASSWORD environment variables (requires the ci task be run first):

$ clojure -T:build deploy

Your library will be deployed to net.clojars.jds02006/mock_server on clojars.org by default.

License

Copyright © 2023 John Swanson

Distributed under the Eclipse Public License version 1.0.