Unintuitive error description

[igorwojda]

class StringMaxCharTest {
    @Test
    fun `SOme test`() {
        maxChar("a") shouldEqual 'a'
    }
}

fun maxChar(str: String): Char? {
    val map = mutableMapOf<Char, Int>()

    str.forEach {
        map[it] = (map[it] ?: 0)  + 1
    }

    return map.maxBy { it.value }?.key
}

Above tests works fine, however when we change our assertion to compare with String, not Char:
maxChar("a") shouldEqual "a"

...tests fails with very unintuitive error description
java.lang.AssertionError: Expected <a>, actual <a>.

It's quite easy to make such a mistake by a programmer, so maybe Kluent can address this issue in a better way eg. by checking if the string has a single character and converting it to Char or display data types in error description

[markusamshove]

This should be a problem within kotlin.test, as we're using their implementation of assertEquals in this case.

We could either raise an issue/pr on their side or write our own implementation and formatting as for #121

[igorwojda]

I think aising a kotlin.test the issue would be a preferable thing to do. I am not that familiar with kotlin.test itself, so I will leave it up to you.

[danielgomezrico]

Another issue with this is that when you run the tests from the terminal it just prints AssertionError withouth the description...

DateTests > test date parse fromString changingTimeZones FAILED
    java.lang.AssertionError at DateTests.kt:20

[javatarz]

@igorwojda: Can you check again? I think kotlin's assertEquals has been fixed.

Test code

@Test
fun beReadableWhenFailing() {
    val exception = assertFailsWith<AssertionError> { maxChar("a") shouldEqual "a" }
    val message = exception.message!!

    message shouldNotStartWith "expected: <a> but was: <a>"
    message shouldStartWith "expected: java.lang.String<a> but was: java.lang.Character<a>"
}

private fun maxChar(str: String): Char = str.map { it }.toSet().last()

Seems pretty clear

[igorwojda]

@javatarz test still fails for me with the wrong exception. Here is my dependency:

testImplementation ("org.amshove.kluent:kluent-android:1.56") {
        exclude group: 'org.jetbrains.kotlin', module: 'kotlin-reflect'
        exclude group: 'org.jetbrains.kotlin', module: 'kotlin-stdlib-jdk8'
    }

[javatarz]

@igorwojda I didn't try this on an independent project. I must admit, I added this test inside the Kluent repo (specifically, this was under the JVM module, not the android one).

Needs further investigation.

[igorwojda]

You can easily reproduce this with my project.

1. Checkout this https://github.com/igorwojda/kotlin-coding-puzzle
2. Open in Android Studio
3. Open MaxOccurrentChar.kt
4. Replace file content with this

package com.igorwojda.string.maxchar

import org.junit.Test
import org.amshove.kluent.shouldEqual

class StringMaxCharTest {
    @Test
    fun `SOme test`() {
        maxChar("a") shouldEqual "a"
    }
}

fun maxChar(str: String): Char? {
    val map = mutableMapOf<Char, Int>()

    str.forEach {
        map[it] = (map[it] ?: 0)  + 1
    }

    return map.maxBy { it.value }?.key
}

5. Run tests is StringMaxCharTest

[markusamshove]

I'll have time to look at it at the weekend. @igorwojda you could try this on a new Android project and/or new JVM project and compare the outputs of gradle dependencies, there could be a discrepancy between Android and jvm kotlin versions

[drcolombo]

If executing
"a" shouldBeEqualTo 'a'
and then getting

Unexpected type
Expected: <kotlin.Char> but was: <kotlin.String>
Expected :kotlin.Char
Actual :kotlin.String

is ok, then I will make a PR.
Basically, before comparing 'actual' and 'expected' we can check if types are the same. If not, then we will throw ComparisonFailedException with 'Unexpected type' message.

[markusamshove]

I like that approach, a PR would be welcome :)