haveElementAt-more-detail (#49)

[AlexCue987]

add more detail to the output of haveElementAt, such as:

         "print if list is too short" {
            shouldThrowAny {
               listOf("a", "b", "c").shouldHaveElementAt(3, "d")
            }.message shouldBe """
            |Collection ["a", "b", "c"] should contain "d" at index 3
            |But it is too short: only 3 elements
            """.trimMargin()
         }
         "print if element does not match" {
            shouldThrowAny {
               listOf("a", "b", "c").shouldHaveElementAt(2, "d")
            }.message shouldBe """
            |Collection ["a", "b", "c"] should contain "d" at index 2
            |Expected: <"c">, but was <"d">
            """.trimMargin()
         }
         "print if element found at another index" {
            shouldThrowAny {
               listOf("a", "b", "c").shouldHaveElementAt(2, "b")
            }.message shouldBe """
            |Collection ["a", "b", "c"] should contain "b" at index 2
            |Expected: <"c">, but was <"b">
            |Element was found at index(es): [1]
            """.trimMargin()
         }
         "print if element found at multiple other indexes" {
            shouldThrowAny {
               listOf("a", "b", "c", "b").shouldHaveElementAt(2, "b")
            }.message shouldBe """
            |Collection ["a", "b", "c", "b"] should contain "b" at index 2
            |Expected: <"c">, but was <"b">
            |Element was found at index(es): [1, 3]
            """.trimMargin()
         }

[sksamuel]

lgtm