CODEWITHSUNDEEP
unit-testingclojure
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Reputation: 27196

Clojure testing : testing the negation of an assertion

This works for me : 

(is  (thrown? AbstractMethodError (.fun obj 1) ))

But this blows up

(is (not (thrown? AbstractMethodError (.fun obj 1) )))

with the following error : 

java.lang.RuntimeException: Unable to resolve symbol: thrown? in this context

Presumably "thrown?" has some special meaning inside the "is" and isn't visible when I put the "not" in the way.

So how can I test a negation of an assertion like thrown?

Upvotes: 5

Views: 679

Answers (1)

Diego Basch
Diego Basch

Reputation: 13079

You're correct, thrown? is a special assertion that must appear after is. If you want to test that an exception is not thrown (in other words, the call evaluated to something), you might want to do something like:

(is (.fun obj 1))

although that has one problem: it would fail if the result is falsey (false, nil). To be completely sure:

(let [r (.fun obj 1)]
  (is (= r r)))

(this is a tautology, and will only fail if it does throw an exception).

Upvotes: 5

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