Add custom printing of Strings to easly distinguish single digit String from Int

[igorwojda]

here is a real-life scenario that made me very confused

listOf(1, 2, "fizz", 4, "buzz") shouldEqual listOf(1, 2, "fizz", 4, "buzz") //ok
listOf(1, 2, "fizz", 4, "buzz") shouldEqual listOf("1", "2", "fizz", 4, "buzz") //fail

The reason of the confusion was this error message :
java.lang.AssertionError: Expected <[1, 2, fizz, 4, buzz]>, actual <[1, 2, fizz, 4, buzz]>.

I think we should consider custom toString conversion to make distinction Int vs String more explicit for all "string prints". The code is not the best but we will get the idea:

val list = listOf(1, "2", "fizz", 4, "buzz")
        println(list) //prints: [1, 2, fizz, 4, buzz]

        println(list.joinToString(
            transform = {
                if (it is String)
                    "\"$it\""
                else
                    it.toString()
            },
            prefix = "[",
            postfix = "]"
        )) //prints: [1, "2", "fizz", 4, "buzz"]

As a result we would get much better error message giving instant hint what is wrong
Before:
java.lang.AssertionError: Expected <[1, 2, fizz, 4, buzz]>, actual <[1, 2, fizz, 4, buzz]>

After
java.lang.AssertionError: Expected <[1, 2, fizz, 4, buzz]>, actual <["1", "2", "fizz", "4", "buzz"]>

As an alternative we could consider handling in special wahy the case where test fails but actuall.toString() == expected.toString(). Then we could make decision about display more information like data types in error message.

Also, keep in mind this is a simplified example, in reality, we will have a function that returns the list making mistake harder to spot in code
listOf(1, 2, "fizz", 4, "buzz") shouldEqual getMyList() //fail

[MarkusAmshove]

This is a good idea!

At the moment we're using assertEquals from kotlin.test, which does the comparison and failure message internally, so we would have to write our own implementation

[AarthiT]

hello, Is this issue up for grabs? can I take this up?

[MarkusAmshove]

hello, Is this issue up for grabs? can I take this up?

Feel free to take it :-)