2 expect blocks in Spock?

Question

I have the following Spock test, which passes:

def "test"() {
  given:
    def name = "John"
  expect:
    name.length() == 4
  when:
    name = name.concat(name)
  then:
    name.length() == 8
}

But when I modify the last then block and make it an expect block...

// previous part same
  expect:
    name.length() == 8

I am getting:

Groovy-Eclipse: Groovy:'expect' is not allowed here; instead, use one of: [and, then]

Is it because multiple expect blocks are not allowed in a single test? If so, is this documented anywhere? There is a similar test here written with given - expect - when - then but it is not clear why a second expect was not used, although what is being asserted is same, just being flipped.

Answer 1

when-expect is simply a syntax error with regard to Spock's specification DSL. The compiler message already tells you how to solve your problem. After when you need then (or and first, if you want to structure your when block into multiple sections). In contrast, expect is a kind of when-then contracted into a single block, because both the stimulus and verifying the response in a condition appear together. Block labels and how to use them is documented here.

Under Specifications as Documentation, you learn more about why you might want to use and and block labels. Under Invocation Order you learn about what you can achieve by using multiple then blocks in contrast to then-and.

You can use multiple expect blocks within one feature, no problem. But you do need to make sure that your when-then (if any) is complete, before you can use another expect.

For example, this is a valid feature:

  def "my feature"() {
    given: true
    and: true
    and: true

    expect: true

    when: true
    and: true

    then: true
    and: true

    then: true

    expect: true
    and: true

    cleanup: true
  }