'be' matchers equality check for Any and null does not compile

[Vladimir Matveev]

Hi,

According to the official docs and API docs when using ShouldMatchers it is possible to use word be for equality comparison to produce more readable tests:

    result should be (null)

However, this does not compile when result is not AnyRef but Any. But it is perfectly correct to check Any value for null:

    ConvertToMap.convert(YNullable(YString), "123") should equal ("123")
    ConvertToMap.convert(YNullable(YString), null) should be (null)

convert() method here returns Any, and it is wholly possible for it to return null. But the compiler rejects this code with the following message:

overloaded method value should with alternatives:
  (notWord: ConvertToMapTest.this.NotWord)ConvertToMapTest.this.ResultOfNotWord[Any] <and>
  (rightMatcher: org.scalatest.matchers.Matcher[Any])Unit
 cannot be applied to (org.scalatest.matchers.Matcher[AnyRef])
    ConvertToMap.convert(YNullable(YString), null) should be (null)
                                                   ^

I understand I can use equal word but it doesn't feel right:

    ConvertToMap.convert(YNullable(YString), null) should equal (null)

 Is it possible to use be word somehow in my case?

Best regards,
Vladimir.

[Bill Venners]

Hi Valdimir,

Well that's my fault. I put in a requirement that be (null) can only be used on AnyRef or below, because Null is a bottom type for AnyRef. In all this time using Scala, it never occurred to me that an Any reference could be null. But obviously it can, it just didn't occur to me. (I don't use null much in Scala.) I thought about this this morning, and I believe I can loosen the type constraint to just Any, so you'd still get a compiler error if you tried something like:

1 should be (null)

If I get that to work I'll deploy a snapshot and let you know. What you could do in the meantime is use an assertion instead.

Bill

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[Vladimir Matveev]

Hi Bill,

Thank you very much, I will be waiting.

понедельник, 15 июля 2013 г., 20:27:39 UTC+4 пользователь Bill Venners написал:

[user]

Hi,

This has been posted a year ago but I'm now facing the same issue. How can I test null?

[Bill Venners]

Hi,

I think this may have gotten forgotten. I'll resurrect it. It will likely need to be in 2.2.0 because it isn't going to be binary compatible. In the meantime, you can probably get your code to compile by giving null a type ascription, like:

null: String

If it is a string.

Bill

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