CODEWITHSUNDEEP
erlangeunit
Sergei Basharov
Sergei Basharov

Reputation: 53850

More human-readable tests messages with Erlang EUnit?

I am used to JavaScript testing, especially its BDD frameworks and libraries like Chai where I can describe tests in a human-readable manner and name tests with strings, e.g. "UserProfile -> Update First Name", then see these message as the output when running tests.

Is it possible to write Erlang tests in a more natural way, or at least, integrate descriptions in to tests run process, not just have them as comments, but see the name of a test which failed?

Upvotes: 2

Views: 132

Answers (1)

legoscia
legoscia

Reputation: 41528

Yes. To add descriptions to tests, the tests need to be "test objects" instead of plain tests. For example, change this test:

foo_test() ->
    run_foo(),
    ensure_foo_works().

to this:

foo_test_() ->
    ?_test(
      begin
        run_foo(),
        ensure_foo_works()
      end).

That is, the name of the function should end with _test_, and the body of the test should be wrapped in a ?_test macro. There are other such "wrapper macros" starting with an underscore; for example, a simple assertion can be rewritten like this:

%% before
check_foo_test() ->
    ?assertEqual(ok, foo()).

%% after
check_foo_test_() ->
    ?_assertEqual(ok, foo()).

Once you have a "test object", you can wrap it in a tuple, where the first element is a string:

foo_test_() ->
    {"Ensure that foo works",
     ?_test(
       begin
         run_foo(),
         ensure_foo_works()
       end)}.

check_foo_test_() ->
    {"Check that foo is ok", ?_assertEqual(ok, foo())}.

Those descriptions will be printed when the test fails. If you run eunit in verbose mode, they will be printed when the test executes as well.

Upvotes: 4

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