Seq empty test with specs2

Question

How can I check if a Seq[String] is empty or not using specs2 in Scala ? I am using seq must be empty or seq.length must be greaterThan(0) but I end up always with type mismatch errors.

ret is Seq[String]

ret.length must be greaterThan(0)

[error] ApiTest.scala:99: type mismatch;
[error]  found   : Int
[error]  required: org.specs2.matcher.Matcher[String]
[error]         ret.length must be greaterThan(0)

You might be more lucky if you posted the exact code and the corresponding error message as given by the compiler. — Samuel Tardieu, Sep 20 '12 at 11:30
Yes please add a more complete example. I think that your case might be an instance of a "classical" type inference issue where you have consecutive matcher expressions separated by newlines, like "ret.length must be greaterThan(0) \n ret.lenght must beLowerThan(10)" (if that's the case I'll edit this comment as a proper answer) — Eric, Sep 20 '12 at 23:56

iwein · Answer 1 · 2016-05-30T18:03:45.213

3

I think the type mismatch error is caused by another bit of code than that which you've posted.

Your example should just work with:

ret must not be empty

I've tried and confirmed to be working correctly:

 "Seq beEmpty test" should {
    "just work" in {
      Seq("foo") must not be empty
    }
  }

You could run into trouble if you use multiple assertions per test, for example the following doesn't compile:

"Seq beEmpty test" should {
  "just work" in {
    List() must be empty
    Seq("foo") must not be empty
  }
}

Which is unexpected, but easily fixed by helping the compiler:

"Seq beEmpty test" should {
  "just work" in {
    List() must beEmpty
    Seq("foo") must not beEmpty
  }
}

edited May 30 '16 at 18:03

answered Apr 27 '13 at 18:03

iwein

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Any reason not to use `beEmpty` by default? – OrangeDog May 25 '16 at 11:17
@OrangeDog only the elegance of 'be empty' over 'beEmpty' can be an argument. They are semantically the same. – iwein May 30 '16 at 17:58
Neither of the options works for mutable.Specification for Specs2 v 4.10.6 – Albert Bikeev Aug 16 '21 at 16:36
@AlbertBikeev you're welcome to edit the answer. It's 8y old now, so maybe the whole question has lost relevance? – iwein Oct 14 '21 at 17:41

score 2 · Answer 2 · answered Nov 20 '12 at 10:12

2

Try using the specs2 matcher have size. Since the size can't be negative, if it's not zero, it must be greater than zero. Therefore, we could use:

ret must not have size (0)

answered Nov 20 '12 at 10:12

Jeff Van Vranken

58
6

Seq empty test with specs2

2 Answers2

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