Anatomy of a test

There are three macros in the clojure.test namespace, which are the trifecta of testing in Clojure: deftest, is, and testing. These three macros are explained as follows:

• deftest: This is similar to def or defn and defines our test function. Tests may call other tests, however, this is a practice that I consider dangerous, as it can result in fragile tests that are, by their nature, rather difficult to debug.

  Usage: (deftest name & body)

• is: This is used to make an assertion in our test. The predicate we pass to is should return a Boolean. We can also optionally provide a message, which will be attached to the assertion and displayed as part of the failure written to stdout.

  Usage: (is form)

  (is form message)

  is also allows the following two special forms that can be used to check for exceptions:

  • thrown?: This is used to ensure that an exception of a specific type is thrown, and if not, fails the test.

    Usage: (thrown? e form)

    Here's an example of this form:

    ...