Inspectors

Inspectors allow us to test elements in a collection. They are extension functions for collections and arrays that test that all, none or some of the elements pass the given assertions. For example, to test that a list of names contains at least two elements which have a length of 7 or more, we can do this:

val xs = listOf("sam", "gareth", "timothy", "muhammad")
xs.forAtLeast(2) {
    it.shouldHaveMinLength(7)
}

Similarly, if we wanted to asset that no elements in a collection passed the assertions, we could do something like:

xs.forNone {
  it.shouldContain("x")
  it.shouldStartWith("bb")
}

If you want to filter a collection to only elements that pass the assertions, you can use the filterMatching method:

xs.filterMatching {
  it.shouldContain("x")
  it.shouldStartWith("bb")
}.shouldBeEmpty()

The full list of inspectors are:

• forAll which asserts every element passes the assertions
• forNone which asserts no element passes
• forOne which asserts only a single element passed
• forAtMostOne which asserts that either 0 or 1 elements pass
• forAtLeastOne which asserts that 1 or more elements passed
• forAtLeast(k) which is a generalization that k or more elements passed
• forAtMost(k) which is a generalization that k or fewer elements passed
• forAny which is an alias for forAtLeastOne
• forSome which asserts that between 1 and n-1 elements passed. Ie, if NONE pass or ALL pass then we consider that a failure.
• forExactly(k) which is a generalization that exactly k elements passed. This is the basis for the implementation of the other methods
• filterMatching which filters the collection to only include elements that pass the assertions