Structing Clojure tests/setup and tear down

[Colin Yates]

Howdy,

I am using clojure.test and have some questions of how to write idiomatic Clojure.  This really isn't about testing at all per-se.

First - I know about fixtures to get (at least) the same as JUnit's before/after behaviour.

My code is a bloomy.  You can configure the bloomy and it does different things based on that behaviour.  Pretty much every test has a different bloomy, *and* that bloomy must be elegantly shut down.

How should I handle this?

At the moment I have the most un-idiomatic way and blunt way of :

[code]

(deftest my-test

  (let [bloomy (create-a-bloomy]

  (try

    (do-something-with-my-bloomy)

    (is (=....))

  (finally (shut-down bloomy))))

[/code]

Yep, try/finally in every test - reminds me of early JDBC libraries before Spring :).  If I understand it correctly, I would end up writing a separate fixture for each and every test, or at least each any every unique set of test context.

I did consider writing a "(defn with-bloomy [bloomy test] (try (test) (finally (shut-down bloomy))))" but I couldn't figure out how to pass my bloomy into the test itself.  I also received lots of "assertion not in expectation" type errors.  To be explicit I would use this as "(with-bloomy (create-a-bloomy) (deftest...)))".

I did consider a variation on the above of passing in a function which only contained the assertions, so "(deftest my-test (let [bloomy...] (with-bloomy bloomy #(is (= 1 (get-something bloomy)))))" but I also ran into similar "assertion not in expectation" type errors, and the indentation in emacs was insane.

I expect a macro might be the answer?

So, how would you solve this?

[Ulises]

Perhaps you're looking for fixtures? http://thornydev.blogspot.co.uk/2012/09/before-and-after-logic-in-clojuretest.html

U

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[Colin Yates]

Hi Ulises,

I don't think I am as that would require essentially a fixture per distinct combinations of test state, which is almost the same number of tests.

Have I missed something?

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[gaz jones]

I think I would use a macro:

(defn with-bloomy-fn [bloomy body]

  (try

   (body)

   (finally

    (shut-down bloomy))))

(defmacro with-bloomy [bloomy & body]

  `(with-bloomy-fn ~bloomy (fn [] ~@body)))

(deftest my-test

  (with-bloomy (create-a-bloomy)

    (...))

FYI code is untested, typing straight in so there may be typos etc.

[Colin Yates]

Thanks Gaz,

I was expecting a macro to be the answer, and seeing how you have used a macro to glue together two functions is really helpful, so thanks a bunch!

[Ulises]

Hey Colin,

Apologies, I missed your "First - I know about fixtures..." line :)

I'd probably +1 Gaz's macro (I've not tested it either but it looks reasonable.)

[Colin Yates]

No worries ;)

[Alex Baranosky]

I tend to have macros for different types of setup/teardowns.  Mostly because clojure.test fixtures always want to wrap *every* test in a file.