How do I verify invokations with specific string matchers in Specs2 with Mockito

Question

I have a test along these lines:

httpClient.post(anyString, anyString) returns (first, second)

//do my thing

there were two(httpClient).post(anyString, anyString)

This works fine, but I want to verify that the first call passes a different body than the second call. The body is rather big and I don't want to do precise matching on a strict example. I've tried this:

there was one(httpClientMock).postMessage(anyString, argThat(contain("FOO"))
there was one(httpClientMock).postMessage(anyString, argThat(contain("FOO"))

That makes Mockito complain:

InvalidUseOfMatchersException: 
 [error] Invalid use of argument matchers!
 [error] 2 matchers expected, 3 recorded:

I've also tried:

  there was one(httpClientMock).postMessage(argThat(contain("foo")), argThat(contain("FOO")))
  there was one(httpClientMock).postMessage(argThat(contain("foo")), argThat(contain("FOO")))

which results in:

Wanted 1 time:
 [error] -> ...
 [error] But was 2 times. Undesired invocation: ...

It seems to me that something like this should be possible, but I can't seem to figure it out. Insights?

score 7 · Accepted Answer · answered Mar 02 '13 at 15:08

I think that this is more of a problem with Mockito to begin with. When you're using Mockito with specs2 and you're in doubt, always drop down to the direct Mockito API:

// simplified httpClient with only one parameter
val httpClient = mock[HttpClient]
httpClient.post(anyString) returns ""

httpClient.post("s1")
httpClient.post("s2")

// forget specs2
// there was two(httpClient).post(anyString)

org.mockito.Mockito.verify(httpClient, org.mockito.Mockito.times(1)).post("s1")

// I guess that you don't want this to pass but it does
org.mockito.Mockito.verify(httpClient, org.mockito.Mockito.times(1)).post("s1")

One possible way around this is to define a matcher that will check the successive values of an argument:

there was two(httpClient).post(consecutiveValues(===("s1"), ===("s2")))

And the consecutiveValues matcher is defined as such:

import matcher._
import MatcherImplicits._

// return a matcher that will check a value against a different
// `expected` matcher each time it is invoked
def consecutiveValues[T](expected: Matcher[T]*): Matcher[T] = {
  // count the number of tested values
  var i = -1

  // store the results
  var results: Seq[(Int, MatchResult[T])] = Seq()

  def result(t: T) = {
    i += 1
    // with Mockito values are tested twice
    // the first time we return the result (but also store it)
    // the second time we return the computed result
    if (i < expected.size) {
      val mr = expected(i).apply(Expectable(t))
      results = results :+ (i, mr)
      mr
     } else results(i - expected.size)._2
  }

  // return a function that is translated to a specs2 matcher
  // thanks to implicits
  // display the failing messages if there are any
  (t: T) => (result(t).isSuccess,
             results.filterNot(_._2.isSuccess).map { case (n, mr) => 
               s"value $n is incorrect: ${mr.message}" }.mkString(", "))
}

You can test the code above. The failure messages are not the best but do the trick. In this situation:

httpClient.post("s1") 
httpClient.post("s2")

there was two(httpClient).post(consecutiveValues(===("s1"), ===("s3")))

You will see:

[error] x test
[error]  The mock was not called as expected: 
[error]  httpClient.post(
[error]      value 1 is incorrect: 's2' is not equal to 's3'
[error]  );
[error]  Wanted 2 times:
[error]  -> at ... 
[error]  But was 1 time:
[error]  -> at ...

I was never in doubt that it was possible. As always, I'm glad I asked :) — iwein, Mar 02 '13 at 19:40
It begs the question, should there be an alternative to Mockito for Scala? — iwein, Mar 02 '13 at 19:41
There is one alternative: http://scalamock.org. But maybe you could ask on the Mockito mailing-list if this is a bug. In that case they might fix it. — Eric, Mar 02 '13 at 23:08
Also, if you want to test more the values than the call numbers you can write: `there was atLeastOne(httpClient).post(anyString) andThen atLeastOne(httpClient).post(===("s2"))` — Eric, Mar 02 '13 at 23:12

How do I verify invokations with specific string matchers in Specs2 with Mockito

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