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re-frame-test

This library provides utilities for testing re-frame applications.

These utilities:

  • allow you to use subscribe in your tests
  • allow you to use dispatch in your tests
  • allow you to run tests on both the JVM and JS platforms
  • allow you to create "end to end" integration tests, involving backend servers

For context, please be sure to read the basic testing tutorial in the main re-frame docs before going any further.

This library primarily supports the testing of Event Handlers, but Subscription Handlers get to come along for the ride.

Implementation

re-frame-test provides two macros which dovetail with cljs.test.

run-test-sync

Execute body as a test, where each dispatch call is executed synchronously (via dispatch-sync), and any subsequent dispatches which are caused by that dispatch are also fully handled/executed prior to control flow returning to your test.

Think of it as though every dispatch in your app had been magically turned into dispatch-sync, and re-frame had lifted the restriction that says you can't call dispatch-sync from within an event handler.

This macro is applicable for most events that do not run async behaviour within the event.

From the todomvc example:

(defn test-fixtures
  []
  ;; change this coeffect to make tests start with nothing
  (rf/reg-cofx
    :local-store-todos
    (fn [cofx _]
      "Read in todos from localstore, and process into a map we can merge into app-db."
      (assoc cofx :local-store-todos
                  (sorted-map)))))

Define some test-fixtures. In this case we have to ignore the localstore in the tests.

(deftest basic--sync
  (rf-test/run-test-sync
    (test-fixtures)
    (rf/dispatch [:initialise-db])

Use the run-test-sync macro to construct the tests and initialise the app state. Note that, the dispatch will be handled before the following code is executed, effectively turning it into a dispatch-sync. Also any changes to the database and registrations will be rolled back at the termination of the test, therefore our fixtures are run within the run-test-sync macro.

        ;; Define subscriptions to the app state
        (let [showing         (rf/subscribe [:showing])
              sorted-todos    (rf/subscribe [:sorted-todos])
              todos           (rf/subscribe [:todos])
              visible-todos   (rf/subscribe [:visible-todos])
              all-complete?   (rf/subscribe [:all-complete?])
              completed-count (rf/subscribe [:completed-count])
              footer-counts   (rf/subscribe [:footer-counts])] 
                 
          ;;Assert the initial state
          (is (= :all @showing))
          (is (empty? @sorted-todos))
          (is (empty? @todos))
          (is (empty? @visible-todos))
          (is (= false (boolean @all-complete?)))
          (is (= 0 @completed-count))
          (is (= [0 0] @footer-counts)) 
             
          ;;Dispatch the event that you want to test, remember that `re-frame-test` 
          ;;will process this event immediately.
          (rf/dispatch [:add-todo "write first test"])
              
          ;;Test that the dispatch has mutated the state in the way that we expect.
          (is (= 1 (count @todos) (count @visible-todos) (count @sorted-todos)))
          (is (= 0 @completed-count))
          (is (= [1 0] @footer-counts))
          (is (= {:id 1, :title "write first test", :done false}
                 (first @todos)))

run-test-async

This macro is applicable for events that do run some async behaviour (usually outside or re-frame, e.g. an http request) within the event.

Run body as an async re-frame test. The async nature means you'll need to use wait-for any time you want to make any assertions that should be true after an event has been handled. It's assumed that there will be at least one wait-for in the body of your test (otherwise you don't need this macro at all).

Note: unlike regular ClojureScript cljs.test/async tests, wait-for takes care of calling (done) for you: you don't need to do anything specific to handle the fact that your test is asynchronous, other than make sure that all your assertions happen with wait-for blocks.

From the todomvc example:

(deftest basic--async
  (rf-test/run-test-async
    (test-fixtures)
    (rf/dispatch-sync [:initialise-db])

Use the run-test-async macro to construct the tests and initialise the app state note that the dispatch-sync must be used as this macro does not run the dispatch immediately like run-test-sync. Also any changes to the database and registrations will be rolled back at the termination of the test, therefore our fixtures are run within the run-test-async macro.

    ;;Define subscriptions to the app state
    (let [showing         (rf/subscribe [:showing])
          sorted-todos    (rf/subscribe [:sorted-todos])
          todos           (rf/subscribe [:todos])
          visible-todos   (rf/subscribe [:visible-todos])
          all-complete?   (rf/subscribe [:all-complete?])
          completed-count (rf/subscribe [:completed-count])
          footer-counts   (rf/subscribe [:footer-counts])]
          
      ;;Assert the initial state
      (is (= :all @showing))
      (is (empty? @sorted-todos))
      (is (empty? @todos))
      (is (empty? @visible-todos))
      (is (= 0 @completed-count))
                    
      ;;Dispatch the event that you want to test, remember 
      ;;that re-frame will not process this event immediately, 
      ;;and need to use the `wait-for` macro to continue the tests.
      (rf/dispatch [:add-todo "write first test"])
          
          
      ;;Wait for the `:add-todo` event to be dispatched 
      ;;(note, in the use of this macro we would typically wait for 
      ;;an event that had been triggered by the successful return of 
      ;;the async event).        
      (rf-test/wait-for [:add-todo-finished]
          
        ;;Test that the dispatch has mutated the state in the way 
        ;;that we expect.    
        (is (= [{:id 1, :title "write first test", :done false}] @todos))

Here we have assumed that the :add-todo event will make some sort of async call which will in turn generate an add-todo-finished event when it has finished. This is not actually the case in the example code.

Running the CLJS tests with Karma

You will need npm, with:

$ npm install -g karma karma-cli karma-cljs-test karma-junit-reporter karma-chrome-launcher

And you will need Chrome.

License

Copyright (c) 2016 Mike Thompson

Distributed under the The MIT License (MIT).


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